Clojure 1.12 produces Java 8 bytecode (same as Clojure 1.10 and 1.11), but this is expected to be the last release using a Java 8 baseline. Future releases will move the bytecode and minimum Java compatibility to a newer Java LTS release.

Clojure users want to use virtual threads on JDK 21. Prior to 1.12, Clojure lazy-seqs and delays, in order to enforce run-once behavior, ran user code under synchronized blocks, which as of JDK 21 don't yet participate in cooperative blocking. Thus if that code did e.g. blocking I/O it would pin a real thread. JDK 21 may emit warnings for this when using -Djdk.tracePinnedThreads=full.

To avoid this pinning, in 1.12 lazy-seq and delay use locks instead of synchronized blocks.

See: CLJ-2804

Fix CVE-2024-22871 detailed in GHSA-vr64-r9qj-h27f:

• CLJ-2839 iterate, cycle, repeat - infinite seqs have infinite hashCode()

CLJ-1327 explicitly sets the Java serialization identifier for the classes in Clojure that implement Java serialization. In Clojure 1.11.0 this changed for two classes unnecessarily and we reverted those changes in Clojure 1.11.1 - this completes that work for the rest of the classes.

Clojure data types have implemented the Java serialization interfaces since Clojure 1.0. Java serialization is designed to save graphs of Java instances into a byte stream. Every class has an identifier (the serialVersionUID) that is automatically generated based on the class name, it's type hierarchy, and the serialized fields. At deserialization time, deserialization can only occur when the available class has an identifier that matches the class id recorded in the serialized bytes.

Clojure has never provided a guarantee of serialization consistency across Clojure versions, but we do not wish to break compatibility any more than necessary and these changes will give us more control over that in the future.

See: CLJ-1327

Updated dependencies:

• spec.alpha dependency to 0.5.238 - changes
• core.specs.alpha dependency to 0.4.74 - changes

See: CLJ-2852

There are many development-time cases where it would be useful to add a library interactively without restarting the JVM - speculative evaluation, adding a known dependency to your project, or adding a library to accomplish a specific task.

Clojure now provides new functions to add libraries interactively, without restarting the JVM or losing the state of your work:

• add-lib takes a lib that is not available on the classpath, and makes it available by downloading (if necessary) and adding to the classloader. Libs already on the classpath are not updated. If the coordinate is not provided, the newest Maven or git (if the library has an inferred git repo name) version or tag are used.
• add-libs is like add-lib, but resolves a set of new libraries and versions together.
• sync-deps calls add-libs with any libs present in deps.edn, but not yet present on the classpath.

These new functions are intended only for development-time interactive use at the repl - using a deps.edn is still the proper way to build and maintain production code. To this end, these functions all check that *repl* is bound to true (that flag is bound automatically by clojure.main/repl). In a clojure.main REPL, these new functions are automatically referred in the user namespace. In other repls, you may need to (require '[clojure.repl.deps :refer :all]) before use.

Library resolution and download are provided by tools.deps. However, you do not want to add tools.deps and its many dependencies to your project classpath during development, and thus we have also added a new api for invoking functions out of process via the Clojure CLI.

See: CLJ-2761, CLJ-2757, CLJ-2788, CLJ-2767, CLJ-2769, CLJ-2770

There are many useful tools you can use at development time, but which are not part of your project's actual dependencies. The Clojure CLI provides explicit support for tools with their own classpath, but there was not previously a way to invoke these interactively.

Clojure now includes clojure.tools.deps.interop/invoke-tool to invoke a tool function out of process. The classpath for the tool is defined in deps.edn and you do not need to add the tool's dependencies to your project classpath.

add-lib functionality is built using invoke-tool but you can also use it to build or invoke your own tools for interactive use. Find more about the function execution protocol on the CLI reference.

See: CLJ-2760, CLJ-2819

For a long time, we've had the clojure.java.shell namespace, but over time Java has provided new APIs for process info, process control, and I/O redirection. This release adds a new namespace clojure.java.process that takes advantage of these APIs and is easier to use. See:

• start - full control over streams with access to the underlying Java objects for advanced usage
• exec - covers the common case of executing an external process and returning its stdout on completion

See: CLJ-2759, CLJ-2777, CLJ-2828, CLJ-2773, CLJ-2776, CLJ-2774, CLJ-2778, CLJ-2779, CLJ-2865

Clojure programmers often want to use Java methods in higher-order functions (e.g. passing a Java method to map). Until now, programmers have had to manually wrap methods in functions. This is verbose, and might require manual hinting for overload disambiguation, or incur incidental reflection or boxing.

Programmers can now use qualified methods as ordinary functions in value contexts - the compiler will automatically generate the wrapping function. The compiler will generate a reflective call when a qualified method does not resolve due to overloading. Developers can supply :param-tags metadata on qualified methods to specify the signature of a single desired method, 'resolving' it.

See: CLJ-2793, CLJ-2844, CLJ-2835

Java members inherently exist in a class. For method values we need a way to explicitly specify the class of an instance method because there is no possibility for inference.

Qualified methods have value semantics when used in non-invocation positions:

• Classname/method - value is a Clojure function that invokes a static method
• Classname/.method - value is a Clojure function that invokes an instance method
• Classname/new - value is a Clojure function that invokes a constructor

Note: developers must use Classname/method and Classname/.method syntax to differentiate between static and instance methods.

Qualified method invocations with param-tags use only the tags to resolve the method. Without param-tags they behave like the equivalent dot syntax, except the qualifying class takes precedence over hints of the target object, and over its runtime type when invoked via reflection.

Note: Static fields are values and should be referenced without parens unless they are intended as function calls, e.g (System/out) should be System/out. Future Clojure releases will treat the field's value as something invokable and invoke it.

See: CLJ-2844, CLJ-2848, CLJ-2847, CLJ-2853, CLJ-2867

When used as values, qualified methods supply only the class and method name, and thus cannot resolve overloaded methods.

Developers can supply :param-tags metadata on qualified methods to specify the signature of a single desired method, 'resolving' it. The :param-tags metadata is a vector of zero or more tags: [tag ...]. A tag is any existing valid :tag metadata value. Each tag corresponds to a parameter in the desired signature (arity should match the number of tags). Parameters with non-overloaded types can use the placeholder _ in lieu of the tag. When you supply :param-tags metadata on a qualified method, the metadata must allow the compiler to resolve it to a single method at compile time.

A new metadata reader syntax ^[tag ...] attaches :param-tags metadata to member symbols, just as ^tag attaches :tag metadata to a symbol.

See: CLJ-2805

Clojure supports symbols naming classes both as a value (for class object) and as a type hint, but has not provided syntax for array classes other than strings.

Developers can now refer to an array class using a symbol of the form ComponentClass/#dimensions, eg String/2 refers to the class of a 2 dimensional array of Strings. Component classes can be fully-qualified classes, imported classes, or primitives. Array class syntax can be used as both type hints and values.

Examples: String/1, java.lang.String/1, long/2.

See: CLJ-2807

Java programs define "functions" with Java functional interfaces (marked with the @FunctionalInterface annotation), which have a single method.

Clojure developers can now invoke Java methods taking functional interfaces by passing functions with matching arity. The Clojure compiler implicitly converts Clojure functions to the required functional interface by constructing a lambda adapter. You can explicitly coerce a Clojure function to a functional interface by hinting the binding name in a let binding, e.g. to avoid repeated adapter construction in a loop, e.g. (let [^java.util.function.Predicate p even?] ...).

See: CLJ-2799, CLJ-2858, CLJ-2856, CLJ-2863, CLJ-2864

Calling methods that take a Supplier (a method that supplies a value) had required writing an adapter with reify. Clojure has a "value supplier" interface with semantic support already - IDeref. All IDeref impls (delay, future, atom, etc) now implement the Supplier interface directly.

See: CLJ-2792, CLJ-2841

Java APIs increasingly return Streams and are hard to consume because they do not implement interfaces that Clojure already supports, and hard to interop with because Clojure doesn't directly implement Java functional interfaces.

In addition to functional interface support, Clojure now provides these functions to interoperate with streams in an idiomatic manner, all functions behave analogously to their Clojure counterparts:

• (stream-seq! stream) => seq
• (stream-reduce! f [init-val] stream) => val
• (stream-transduce! xf f [init-val] stream) => val
• (stream-into! to-coll [xf] stream) => to-coll

All of these operations are terminal stream operations (they consume the stream).

See: CLJ-2775

Java collections implement streams via "spliterators", iterators that can be split for faster parallel traversal. PersistentVector now provides a custom spliterator that supports parallelism, with greatly improved performance.

See: CLJ-2791

Partitioning of a collection uses a series of takes (to build a partition) and drops (to skip past that partition). CLJ-2713 adds a new internal interface (IDrop) indicating that a collection can drop more efficiently than sequential traversal, and implements that for persistent collections and algorithmic collections like range and repeat. These optimizations are used in drop, nthrest, and nthnext.

Additionally, there are new functions partitionv, partitionv-all, and splitv-at that are more efficient than their existing counterparts and produce vector partitions instead of realized seq partitions.

See: CLJ-2713, CLJ-2742, CLJ-2740, CLJ-2715, CLJ-2718, CLJ-2772, CLJ-2741

Interning a var in a namespace (vs aliasing) must create a stable reference that is never displaced, so that all references to an interned var get the same object. There were some cases where interned vars could get displaced and those have been tightened up in 1.12.0-alpha1. If you encounter this situation, you'll see a warning like "REJECTED: attempt to replace interned var #'some-ns/foo with #'other-ns/foo in some-ns, you must ns-unmap first".

This addresses the root cause of an issue encountered with Clojure 1.11.0, which added new functions to clojure.core (particularly abs). Compiled code from an earlier version of Clojure with var names that matched the newly added functions in clojure.core would be unbound when loaded in a 1.11.0 runtime. In addition to CLJ-2711, we rolled back a previous fix in this area (CLJ-1604).

See: CLJ-2711

• CLJ-2726 #uuid data reader - Fix exception on invalid input so it flows through reader
• CLJ-2813 anonymous function arg reader - no longer accepts invalid arg symbols
• CLJ-2843 Reflective calls to Java methods that take primitive long or double now work when passed a narrower boxed number at runtime (Integer, Short, Byte, Float). Previously, these methods were not matched during reflection and an error was thrown.
• CLJ-2145 - Fix clearing of closed overs in ^:once fns
• CLJ-2317 - recur to head of :once fn cancels once

• CLJ-2739 ArityException - Fix message when function incorrectly called with >20 args
• CLJ-2709 range - Use optimized range for int args
• CLJ-2721 range - Fix invalid arg order when adding meta to non-optimized range
• CLJ-2683 with-open - Fix to not qualify .close method on expansion
• CLJ-2724 clojure.java.io/do-copy - Fix incorrect type hint
• CLJ-2640 ex-info - now handles nil data map
• CLJ-2717 nthrest now returns rest output on n=0 or past end of seq
• CLJ-1872 empty? - adds support for counted? collections
• CLJ-2694 Fix ratio invariants violated when using Long/MIN_VALUE
• CLJ-2568 clojure.walk/walk - preserve metadata on lists and seqs
• CLJ-2686 clojure.core.server/parse-props - Fix exception if system properties concurrently modified during initialization
• CLJ-2645 PrintWriter-on should support auto-flush, and prepl should use it for the err stream
• CLJ-2698 defprotocol - ignore unused primitive return type hints
• CLJ-2783 replace calls to deprecated URL constructor

• CLJ-2225 assert and \*assert* - improve docstrings to add context
• CLJ-2290 into - add 0- and 1-arity to docstring
• CLJ-2552 reify - improve docstring and fix example
• CLJ-1385 transient - include usage model from reference docs

• CLJ-2145 - Fix clearing of closed overs in ^:once fns
• CLJ-2317 - recur to head of :once fn cancels once

• CLJ-2843 - Reflective calls to Java methods that take primitive long or double now work when passed a narrower boxed number at runtime (Integer, Short, Byte, Float). Previously, these methods were not matched during reflection and an error was thrown.

Fixes CVE-2024-22871 detailed in GHSA-vr64-r9qj-h27f:

• CLJ-2839 - iterate, cycle, repeat - infinite seqs have infinite hashCode()

• CLJ-2701 Pin serialVersionUID for Keyword and ArraySeq back to 1.10.3 values to retain binary serialization

Because XML external entity (XXE) attacks can be used to disclose local files using file schemes or relative paths in the system identifier, clojure.xml/parse now disables external entity processing by default.

See: https://owasp.org/www-community/vulnerabilities/XML_External_Entity_(XXE)_Processing

This change disables the following SAX parser features:

• http://apache.org/xml/features/nonvalidating/load-external-dtd
• http://xml.org/sax/features/external-general-entities
• http://xml.org/sax/features/external-parameter-entities

If you rely on these features, modify your calls to clojure.xml/parse to explicitly supply startparse-sax function as the final argument: (clojure.xml/parse the-string clojure.xml/startparse-sax) This modification also works on prior Clojure versions.

• CLJ-2611 clojure.xml now disables XXE processing by default

Updated dependencies:

• spec.alpha dependency to 0.3.218 - changes
• core.specs.alpha dependency to 0.2.62 - changes

Keyword arguments are optional trailing variadic arguments of the form akey aval bkey bval...​. In Clojure 1.11, functions taking keyword arguments can now be passed a map instead of or in addition to and following the key/value pairs. When a lone map is passed, it is used for destructuring, else a trailing map is added to the key/value pair map by conj.

Also see: https://clojure.org/news/2021/03/18/apis-serving-people-and-programs

• CLJ-2603 Clojure keyword argument functions now also accept a map

Spec (and other libs) rely on qualified keywords as spec names. Namespace aliasing in ns makes long names shorter but required namespaces to be loadable. This change adds :as-alias to require, which is like :as but does not require the namespace to load.

• CLJ-2123 Add :as-alias option to require like :as but not load
• CLJ-2665 Fix require with :as and :as-alias to load

Added a new clojure.math namespace which provides wrappers for the functions available in java.lang.Math. These functions are narrowed to only long and double overloads and provide primitive support without reflection.

In addition, the following functions were added to clojure.core:

• abs - absolute value in optimized form for all Clojure numeric types (long, double, ratio, bigint, bigdecimal)

• NaN? - predicate for doubles to check whether "not a number"

• infinite? - predicate for doubles to check whether positive or negative infinity

• CLJ-2668 Add NaN? and infinite? predicates

• CLJ-2664 Add clojure.java.math namespace, wrappers for java.lang.Math

• CLJ-2673 Add abs, and update min and max to use Math impls when possible

• CLJ-2677 clojure.math - fix method reflection in bodies and inlines, fix docstrings, renamed

• CLJ-2689 Fix clojure.math tests to be more tolerant of floating point comparisons

Added the following parsing functions to clojure.core:

• parse-double - parses floating point number, including scientific notation
• parse-long - parses integer in long range
• parse-boolean - parses "true" or "false" to the canonical boolean values
• parse-uuid - parses a UUID string to java.util.UUID

All of these functions expect a string argument and return either the parsed value or nil if the value is in invalid format.

• CLJ-2667 Add functions to parse a single long/double/uuid/boolean from a string

Added random-uuid, a function to construct a random java.util.UUID.

• CLJ-1925 Add random-uuid

Added:

• update-keys - applies a function to every key in a map, m f => {(f k) v ...}

• update-vals - applies a function to every value in a map, m f => {k (f v) ...}

• CLJ-1959 Add implementation of update-keys

• CLJ-2651 Add implementation of update-vals

Added iteration, to repeatedly apply a (possibly impure) step function with continuation state. This can be used e.g. to consume APIs that return paginated or batched data.

• CLJ-2555 Add iteration generator function
• CLJ-2690 Improve iteration docstring and arg names
• CLJ-2685 Fix iteration generative test failure

• CLJ-2680 Fix type hinting a primitive local with matching type hint to not error
• CLJ-1180 Fix resolution of class type hints in defprotocol
• CLJ-1973 Make order of emitted protocol methods in generated classes reproducible

• CLJ-1879 IKVReduce - make IPersistentMap case faster and extend to Object, detaching it from any fully enumerable set of types
• CLJ-2065 IKVReduce - add direct support for SubVector
• CLJ-2663 Fix vector = not terminating when called with infinite sequence
• CLJ-2679 Fix hash collisions in case expressions on symbols
• CLJ-2600 Don't block realized? of delay on pending result
• CLJ-2649 Fix order of checks in some-fn and every-pred for 3 predicate case to match other unrollings
• CLJ-2234 Fix multimethod preferences to correctly use local hierarchy when it exists
• CLJ-2556 Fix into completion so halt-when works

• CLJ-1808 map-invert should use reduce-kv and transient
• CLJ-2621 Fix unnecessary boxing of unused return in statement context for instance method expr
• CLJ-2670 Use Math.exact... methods for checked long math ops for performance
• CLJ-2636 Get rid of reflection on java.util.Properties when defining *clojure-version*
• CLJ-1509 AOT compile clojure.instant, clojure.uuid, clojure.core.reducers in build

• CLJ-2529 Fix incorrect reporting of runtime errors as compiler errors in calls through Compiler.load()
• CLJ-2350 Improve keyword arity exception message

• CLJ-2249 Clarify get docstring regarding sets, strings, arrays, ILookup
• CLJ-2488 Add definition to reify docstring
• CLJ-1360 Update clojure.string/split docstring regarding trailing empty parts
• CLJ-2444 Fix typo in test-vars docstring
• CLJ-2666 Make Clojure Java API javadoc text match the example

• CLJ-2493 clojure.java.browse - Fix browse-url hanging on call to xdg-open
• CLJ-1908 clojure.test - Add run-test and run-test-var to run single test with fixtures and report
• CLJ-1379 clojure.test - Fix quoting of :actual form in :pass maps
• CLJ-2620 clojure.server - Fix asymmetric handling of :exception :vals in prepl
• CLJ-2387 clojure.server - Fix off-by-one in socket server port validation

• CLJ-2564 Improve error message for case

• CLJ-2453 Enable reader conditionals in Clojure prepl

Updated dependencies:

• spec.alpha dependency to 0.2.194 - changes
• core.specs.alpha dependency to 0.2.56 - changes

• CLJ-1472 Ensure monitor object is on stack, for verifiers
• CLJ-2517 More fixes for invocation of static interface methods with primitive args
• CLJ-2492 Remove uses of deprecated Class.newInstance()
• CLJ-2534 Fix javadoc urls for JDK 11
• CLJ-2571 Add Throwable return type hint to ex-cause
• CLJ-2572 Avoid reflection in clojure.data
• CLJ-2502 Fix reflection warnings in clojure.stacktrace/print-stack-trace
• CLJ-2597 proxy should emit Java 1.8 bytecode

• CLJ-2580 Fix case expression branch analysis that resulted in compilation error
• CLJ-2564 Improve error message for case
• CLJ-2585 nth with not-found on regex matcher returns not-found on last group index
• CLJ-1364 vector-of does not implement equals or hashing methods
• CLJ-2549 vector-of does not implement IObj for metadata
• CLJ-1187 quoted metadata on empty literal colls is lost
• CLJ-2459 ExceptionInInitializerError if jars executed with java -jar

• CLJ-2469 Fix errors in printing some maps with namespace syntax
• CLJ-1445 pprint doesn't print collection metadata when *print-meta* is true

• CLJ-2295 Eliminate duplicate doc string printing for special forms
• CLJ-2495 prepl docstring is incorrect
• CLJ-2169 conj has out-of-date :arglists

• CLJ-1005 Use transient map in zipmap

Recent builds of Java 8 (u202), 11 (11.0.2), 12, and 13 included some changes that drastically affect optimization performance of calls from static initializers to static fields. Clojure provides support for loading code on startup from a user.clj file and this occurred in the static initializer of the Clojure runtime (RT) class and was thus affected.

This issue may eventually be resolved in Java, but in Clojure we have modified runtime initialization to avoid loading user.clj in a static initializer, which mitigates the case where this caused a performance degradation.

• CLJ-2484 Significant performance regression of code loaded in user.clj in Java 8u202/11.0.

clojure.main is frequently used as a Clojure program launcher by external tools. Previously, uncaught exceptions would be automatically printed by the JVM, which would also print the stack trace.

This release will now catch exceptions and use the same error triage and printing functionality as the Clojure repl. The full stack trace, ex-info, and other information will be printed to a target specified by the configuration.

The three available error targets are:

• file - write to a temp file (default, falls back to stderr)
• stderr - write to stderr stream
• none - don't write

These error targets can be specified either as options to clojure.main, or as Java system properties (flags take precedence). When invoking clojure.main (or using the clj tool), use --report <target>. For Java system property, use -Dclojure.main.report=<target>.

• CLJ-2463 Improve error printing in clojure.main with -m, -e, etc
• CLJ-2497 Put error report location on its own line
• CLJ-2504 Provide more options for error reporting in clojure.main

• CLJ-2499 Some compiler expr evals report as wrong error phase
• CLJ-2491 Updated fragile tests so Clojure test suite runs on Java 12

Clojure 1.10 now requires Java 8 or above. There were a number of updates related to this change and/or Java compatibility fixes for Java 8, 9, 10, and 11:

• CLJ-2363 Bump to Java 8 as minimum requirement, update embedded ASM to 6.2, remove reliance on jsr166 jar, update javadoc links, and remove conditional logic.
• CLJ-2367 ASM regression fix
• CLJ-2284 Fix invalid bytecode generation for static interface method calls in Java 9
• CLJ-2066 Add reflection fallback for --illegal-access warnings in Java 9
• CLJ-2330 Fix brittle test that fails on Java 10 build due to serialization drift
• CLJ-2374 Add type hint to address reflection ambiguity in JDK 11
• CLJ-2375 Fix usage of deprecated JDK apis
• CLJ-2414 Regression in reflectively finding default methods

Updated dependencies:

• spec.alpha dependency to 0.2.176 - changes
• core.specs.alpha dependency to 0.2.44 - changes

Clojure errors can occur in several distinct "phases" - reading source, macroexpansion, compilation, execution, and result printing. Clojure (and the REPL) now identify these phases in the exception and the message.

The read/macroexpand/compile phases produce a CompilerException and indicate the location in the caller source code where the problem occurred (previously macroexpansion reported the error in the macroexpansion stack). CompilerException now implements IExceptionInfo and ex-data will report exception data including the following (optional) keys:

• :clojure.error/phase - phase (:read-source, :macro-syntax-check, :macroexpansion, :compile-syntax-check, :compilation, :execution, :read-eval-result, :print-eval-result)
• :clojure.error/source - source file
• :clojure.error/line - line in source file
• :clojure.error/column - column of line in source file
• :clojure.error/symbol - symbol being macroexpanded or compiled
• :clojure.error/class - cause exception class symbol
• :clojure.error/cause - cause exception message
• :clojure.error/spec - explain-data for spec errors

clojure.main also contains two new functions: ex-triage and ex-str that can be used by external tools to mimic some or all of the Clojure repl reporting. ex-triage takes the output of Throwable->map and produces a concise analysis of the error phase, cause, etc (same keys as above). ex-str takes that analysis data and produces a message to print at the repl.

• CLJ-2373 Detect phase and overhaul exception message and printing
• CLJ-2415 Error cause should always be on 2nd line of error message
• CLJ-2420 Refinement of error phases, ex-triage, execution error line reporting
• CLJ-2427 CompilerException.toString() can throw if making message during initialization
• CLJ-2430 Elevate phase in throwable data and conveyance for prepl
• CLJ-2435 Include root cause class name in compilation and macroexpansion error phases
• CLJ-2438 Demunge source symbol in execution error messages

defprotocol has a new option :extend-via-metadata. When :extend-via-metadata is true, values can extend protocols by adding metadata where keys are fully-qualified protocol function symbols and values are function implementations. Protocol implementations are checked first for direct definitions (defrecord, deftype, reify), then metadata definitions, then external extensions (extend, extend-type, extend-protocol).

tap is a shared, globally accessible system for distributing a series of informational or diagnostic values to a set of (presumably effectful) handler functions. It can be used as a better debug prn, or for facilities like logging etc.

tap> sends a value to the set of taps. Taps can be added with add-tap and will be called with any value sent to tap>. The tap function may (briefly) block (e.g. for streams) and will never impede calls to tap>, but blocking indefinitely may cause tap values to be dropped. If no taps are registered, tap> discards. Remove taps with remove-tap.

read string is a new function that mimics read but also captures the string that is read and returns both the read value and the (whitespace-trimmed) read string. read string requires a LineNumberingPushbackReader.

prepl is a new stream-based REPL with structured output (suitable for programmatic use). Forms are read from the reader, evaluated, and return data maps for the return value (if successful), output to *out* (possibly many), output to *err* (possibly many), or tap> values (possibly many).

New functions in clojure.core.server:

• prepl - the repl
• io-prepl - a prepl bound to *in* and *out* suitable for use with the Clojure socket server
• remote-prepl - a prepl that can be connected to a remote prepl over a socket

prepl is alpha and subject to change.

clojure.datafy is a facility for object to data transformation. The datafy and nav functions can be used used to transform and (lazily) navigate through object graphs. The data transformation process can be influenced by consumers using protocols or metadata.

datafy is alpha and subject to change.

• CLJ-2429 Datafy JavaReflector

These functions have been added to match existing functions in ClojureScript to increase the portability of error-handling code:

• ex-cause - extract the cause exception
• ex-message - extract the cause message

This function has been added to construct a PrintWriter implementation whose behavior on flush and close is provided as functions:

• PrintWriter-on - create a PrintWriter from flush-fn and close-fn

The following function has been added, extending resolve:

• requiring-resolve - resolve or, if needed, require symbol's namespace, then resolve
• serialized-require - like require but for use in asynchronous load uses

• CLJ-1279 Report correct arity count for function arity errors inside macros
• CLJ-2386 Omit ex-info construction frames
• CLJ-2394 Warn in pst that stack trace for syntax error failed before execution
• CLJ-2396 Omit :in clauses when printing spec function errors if using default explain printer
• CLJ-1797 Mention cljc in error when require fails
• CLJ-1130 Improve error message when unable to match static method

• CLJ-2044 clojure.instant - add arglist meta for functions
• CLJ-2257 proxy - fix typo
• CLJ-2332 remove-tap - fix repetition
• CLJ-2122 flatten - describe result as lazy

• CLJ-1654 Reuse seq in some
• CLJ-1366 The empty map literal is read as a different map each time
• CLJ-2362 with-meta should return identity when new meta is identical to prior

• symbol can now take a var or a keyword argument
• CLJ-1209 Print ex-data in clojure.test error reports
• CLJ-2163 Add test for var serialization
• CLJ-2417 sort and sort-by should retain meta

• CLJ-2297 PersistentHashMap leaks memory when keys are removed with without
• CLJ-1587 PersistentArrayMap’s assoc doesn’t respect HASHTABLE_THRESHOLD
• CLJ-2050 Remove redundant key comparisons in HashCollisionNode
• CLJ-2089 Sorted colls with default comparator don’t check that first element is Comparable

• CLJ-2031 clojure.walk/postwalk does not preserve MapEntry type objects
• CLJ-2349 Report correct line number for uncaught ExceptionInfo in clojure.test
• CLJ-1764 partition-by runs infinite loop when one element of infinite partition is accessed
• CLJ-1832 unchecked-* functions have different behavior on primitive longs vs boxed Longs

• CLJ-1403 ns-resolve might throw ClassNotFoundException but should return nil
• CLJ-2407 Fix bugs in Clojure unit tests
• CLJ-1079 In reader, don't ignore explicit :line :col meta

spec is a new core library for describing, validating, and testing the structure of data and functions.

For more information, see:

• About spec
• spec Guide

Note that spec is in alpha state and API compatibility is not guaranteed. Also, spec and the specs for the Clojure core API are distributed as external libraries that must be included to use Clojure.

Several enhancements have been made to add support for working with maps with qualified keys:

• Map namespace syntax - specify the default namespace context for the keys (or symbols) in a map once - #:car{:make "Jeep" :model "Wrangler"}. For more information see https://clojure.org/reference/reader#_maps (CLJ-1910)
• Destructuring support - namespaced map keys can now specified once as a namespace for :keys or :syms. For more information see https://clojure.org/reference/special_forms#_map_binding_destructuring (CLJ-1919)
• *print-namespace-maps* - by default maps will not print with the map namespace syntax except in the clojure.main repl. This dynamic var is a flag to allow you to control whether the namespace map syntax is used.

Specs rely heavily on predicates and many new type and value oriented predicates have been added to clojure.core:

• boolean?
• int? pos-int? neg-int? nat-int?
• double?
• ident? simple-ident? qualified-ident?
• simple-symbol? qualified-symbol?
• simple-keyword? qualified-keyword?
• bytes? (for byte[])
• indexed?
• uuid? uri?
• seqable?
• any?

More support has been added for the notion of instants in time:

• Added a new protocol Inst for instant types
• Inst is extended for java.util.Date
• Inst is optionally extended for java.time.Instant in Java 1.8
• New functions that work for instants: inst?, inst-ms

These are some other new functions in clojure.core:

• bounded-count - a count that avoids realizing the entire collection beyond a bound
• swap-vals! and reset-vals! - new atom functions that return both the old and new values (CLJ-1454)
• halt-when - new transducer that ends transduction when pred is satisfied

• Can now bind *reader-resolver* to an impl of LispReader$Resolver to control the reader’s use of namespace interactions when resolving autoresolved keywords and maps.
• Add new ## reader macro for symbolic values, and read/print support for double vals ##Inf, ##-Inf, ##NaN (CLJ-1074)

If a macro has a spec defined via fdef, that spec will be checked at compile time. Specs have been defined for many clojure.core macros and errors will be reported for these based on the specs at compile time.

• doc will now report specs for functions with specs defined using fdef
• doc can now be invoked with a fully-qualified keyword representing a spec name

• Improved update-in performance
• Optimized seq & destructuring
• CLJ-2210 Cache class derivation in compiler to improve compiler performance
• CLJ-2188 slurp - mark return type as String
• CLJ-2070 clojure.core/delay - improve performance
• CLJ-1917 Reducing seq over string should call String/length outside of loop
• CLJ-1901 amap - should call alength only once
• CLJ-1224 Record instances now cache hasheq and hashCode like maps
• CLJ-99 min-key and max-key - evaluate k on each arg at most once

• Added Var serialization for identity, not value
• into now has a 0-arity (returns []) and 1-arity (returns the coll that's passed)
• CLJ-2184 Propagate meta in doto forms to improve error reporting
• CLJ-1744 Clear unused locals, which can prevent memory leaks in some cases
• CLJ-1673 clojure.repl/dir-fn now works on namespace aliases
• CLJ-1423 Allow vars to be invoked with infinite arglists (also, faster)

• CLJ-2204 Disable serialization of proxy classes to avoid potential issue when deserializing

• CLJ-2170 fix improperly located docstrings
• CLJ-2156 clojure.java.io/copy - doc char[] support
• CLJ-2104 clojure.pprint docstring - fix typo
• CLJ-2051 clojure.instant/validated docstring - fix typo
• CLJ-2039 deftype - fix typo in docstring
• CLJ-2028 filter, filterv, remove, take-while - fix docstrings
• CLJ-1918 await - improve docstring re shutdown-agents
• CLJ-1873 require, *data-readers* - add .cljc files to docstrings
• CLJ-1859 zero?, pos?, neg? - fix docstrings
• CLJ-1837 index-of, last-index-of - clarify docstrings
• CLJ-1826 drop-last - fix docstring
• CLJ-1159 clojure.java.io/delete-file - improve docstring

• clojure.core/Throwable->map formerly returned StackTraceElements which were later handled by the printer. Now the StackTraceElements are converted to data such that the return value is pure Clojure data, as intended.
• CLJ-2091 clojure.lang.APersistentVector#hashCode is not thread-safe
• CLJ-2077 Clojure can't be loaded from the boot classpath under java 9
• CLJ-2048 Specify type to avoid ClassCastException when stack trace is elided by JVM
• CLJ-1914 Fixed race condition in concurrent range realization
• CLJ-1887 IPersistentVector.length() - implement missing method
• CLJ-1870 Fixed reloading a defmulti removes metadata on the var
• CLJ-1860 Make -0.0 hash consistent with 0.0
• CLJ-1841 bean - iterator was broken
• CLJ-1793 Clear 'this' before calls in tail position
• CLJ-1790 Fixed error extending protocols to Java arrays
• CLJ-1714 using a class in a type hint shouldn’t load the class
• CLJ-1705 vector-of - fix NullPointerException if given unrecognized type
• CLJ-1398 clojure.java.javadoc/javadoc - update doc urls
• CLJ-1371 Numbers.divide(Object, Object) - add checks for NaN
• CLJ-1358 doc - does not expand special cases properly (try, catch)
• CLJ-1242 equals doesn't throw on sorted collections
• CLJ-700 contains?, get, and find broken for transient collections

Direct linking can be enabled with -Dclojure.compiler.direct-linking=true

Direct linking allows functions compiled with direct linking on to make direct static method calls to most other functions, instead of going through the var and the Fn object. This can enable further optimization by the jit, at a cost in dynamism. In particular, directly-linked calls will not see redefinitions.

With this change, clojure.core itself is compiled with direct linking and therefore other namespaces cannot redefine core fns and have those redefinitions seen by core code.

A new metadata key ^:redef is provided. A function declared with this key can be redefined and will never be direct linked. Also, functions declared as ^:dynamic will never be direct linked.

• CLJ-1809
• CLJ-1805
• CLJ-1854
• CLJ-1856

Several new string functions were added to clojure.string to increase portability and reduce the need for Java interop calls:

• index-of - search for the index of a char or string in a string

• last-index-of - search for the index of a char or string backwards in a string

• starts-with? - true if string starts with a substring

• ends-with? - true if string ends with a substring

• includes? - true if string includes a substring

• CLJ-1449

The Clojure runtime now has the ability to start a socket server at initialization based on system properties. One expected use for this is serving a socket-based REPL, but it also has many other potential uses for dynamically adding server capability to existing programs without code changes.

A socket server will be started for each JVM system property like clojure.server.<server-name>. The value for this property is an edn map representing the configuration of the socket server with the following properties:

• address - host or address, defaults to loopback
• port - positive integer, required
• accept - namespaced symbol of function to invoke on socket accept, required
• args - sequential collection of args to pass to accept
• bind-err - defaults to true, binds *err* to socket out stream
• server-daemon - defaults to true, socket server thread doesn't block exit
• client-daemon - defaults to true, socket client thread doesn't block exit

Additionally, there is a repl function provided that is slightly customized for use with the socket server in clojure.core.server/repl.

Following is an example of starting a socket server with a repl listener. This can be added to any existing Clojure program to allow it to accept external REPL clients.

-Dclojure.server.repl="{:port 5555 :accept clojure.core.server/repl}"

An example client you can use to connect to this socket repl is telnet:

$ telnet 127.0.0.1 5555
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
user=> (println "hello")
hello

See:

• CLJ-1671
• CLJ-1853
• Socket REPL design page
• CLJ-1829

• CLJ-1778 let-bound namespace-qualified bindings should throw (if not map destructuring)
• CLJ-1456 Compiler now errors if too few or too many arguments to throw
• CLJ-1282 quote now throws if passed more or less than one arg
• CLJ-1210 Improved error message for (clojure.java.io/reader nil)

• CLJ-1060 'list*' returns not a list
• CLJ-1722 Typo in the docstring of 'with-bindings'
• CLJ-1769 Docstrings for *' and ' refer to * and
• CLJ-1414 sort and sort-by now indicate sort is stable in docstring

• CLJ-703 Improve writeClassFile performance
• CLJ-1765 areduce performance improvements
• CLJ-1724 Remove unnecessary call to seq() in LazySeq.hashCode()
• CLJ-1295 Improved array-map dissoc performance
• CLJ-1277 Speed up printing of time instants with type hints
• CLJ-1259 Speed up pprint and cl-format with type hints
• CLJ-668 Improve slurp performance by using StringWriter and jio/copy

• CLJ-1208 Optionally require namespace on defrecord class init
• CLJ-1823 Document new :load-ns option to defrecord/deftype
• CLJ-1810 ATransientMap now marked public
• CLJ-1653 str of an empty list should be "()"
• CLJ-1567 Removed unused local in condp implementation
• CLJ-1351 Unused swapThunk method was being emitted for fns with keyword callsites
• CLJ-1329 Removed unused local in PersistentVector.cons()
• CLJ-1831 Add clojure.core/map-entry? predicate
• CLJ-1845 Make clojure.core/load dynamic so it can be redef'ed even with direct linking

• CLJ-130 Namespace metadata lost in AOT compile
• CLJ-1134 star-directive in clojure.pprint/cl-format with at-prefix ("~n@*") does not obey its specification
• CLJ-1137 Metadata on a def gets evaluated twice
• CLJ-1157 Classes generated by gen-class aren't loadable from remote codebase
• CLJ-1225 quot overflow issues around Long/MIN_VALUE for BigInt
• CLJ-1313 Correct a few unit tests
• CLJ-1319 array-map fails lazily if passed an odd number of arguments
• CLJ-1361 pprint with code-dispatch incorrectly prints a simple ns macro call
• CLJ-1390 pprint a GregorianCalendar results in Arity exception
• CLJ-1399 field name unmunged when recreating deftypes serialized into bytecode
• CLJ-1485 clojure.test.junit/with-junit-output doesn't handle multiple expressions
• CLJ-1528 clojure.test/inc-report-counter is not thread-safe
• CLJ-1533 invokePrim path does not take into account var or form meta
• CLJ-1562 some->,some->>,cond->,cond->> and as-> doesn't work with (recur)
• CLJ-1565 pprint produces infinite output for a protocol
• CLJ-1588 StackOverflow in clojure.test macroexpand with are and anon fn
• CLJ-1644 into-array fails for sequences starting with nil
• CLJ-1645 protocol class does not set the source file
• CLJ-1657 proxy bytecode calls super methods of abstract classes
• CLJ-1659 compile leaks files
• CLJ-1761 clojure.core/run! does not always return nil per docstring
• CLJ-1782 Spelling mistake in clojure.test/use-fixtures
• CLJ-1785 Reader conditionals throw when returning nil
• CLJ-1766 Serializing deserializing lists breaks their hash
• CLJ-1609 Edge case in Reflector's search for a public method declaration
• CLJ-1586 Compiler doesn't preserve metadata for LazySeq literals
• CLJ-1232 Functions with non-qualified return type hints will now work without import from other namespace
• CLJ-1812 Fix test failure on windows due to line endings
• CLJ-1380 3-arg ExceptionInfo constructor permitted nil data
• CLJ-1226 set! of a deftype field using field-access syntax caused ClassCastException
• Records and types without fields eval to empty map
• CLJ-1827 Fix reflection warning introduced in CLJ-1259
• CLJ-1453 Ensure that all Iterator implementations throw NoSuchElementException on next() when exhausted
• CLJ-1868 Avoid compiler NPE when checking class return type

Please be aware of the following issues when upgrading to Clojure 1.7.

Seqs are fundamentally incompatible with Java iterators that return the same mutating object on every call to next(). Some Clojure libraries incorrectly rely on calling seq on such iterators.

In 1.7, iterator-seqs are chunked, which will cause many of these incorrect usages to return incorrect results immediately.

The seq and iterator-seq docstrings have been updated to include an explicit warning. Libraries that incorrectly use seq and iterator-seq will need to be fixed before running against 1.7.

• CLJ-1669
• CLJ-1738

Prior to Clojure 1.7, transients would allow modification only from the thread that created the transient. This check has been removed. It is still a requirement that transients should be updated by only a single thread at a time.

This constraint was relaxed to allow transients to be used in cases where code is multiplexed across multiple threads in a pool (such as go blocks in core.async).

Invoking keys or vals on a custom map type that implements IPersistentMap will now use the Iterable iterator() method instead of accessing entries via the seq of the map. There have been no changes in the type hierarchy (IPersistentMap has always extended Iterable) but former map-like instances may have skipped implementing this method in the past.

• CLJ-1602

Transducers is a new way to decouple algorithmic transformations from their application in different contexts. Transducers are functions that transform reducing functions to build up a "recipe" for transformation.

Also see: http://clojure.org/transducers

Many existing sequence functions now have a new arity (one fewer argument than before). This arity will return a transducer that represents the same logic but is independent of lazy sequence processing. Functions included are:

• map
• mapcat
• filter
• remove
• take
• take-while
• drop
• drop-while
• take-nth
• replace
• partition-by
• partition-all
• keep
• keep-indexed
• map-indexed
• distinct
• interpose

Additionally some new transducer functions have been added:

• cat - concatenates the contents of each input
• dedupe - removes consecutive duplicated values
• random-sample - returns items from coll with random probability

And this function can be used to make completing transforms:

• completing

There are also several new or modified functions that can be used to apply transducers in different ways:

• sequence - takes a transformation and a coll and produces a lazy seq
• transduce - reduce with a transformation (eager)
• eduction - returns a reducible/iterable of applications of the transducer to items in coll. Applications are re-performed with every reduce/iterator.

There have been a number of internal changes to support transducers:

• volatiles - there are a new set of functions (volatile!, vswap!, vreset!, volatile?) to create and use volatile "boxes" to hold state in stateful transducers. Volatiles are faster than atoms but give up atomicity guarantees so should only be used with thread isolation.
• array iterators - added support for iterators over arrays
• conj can be used as a reducing function and will conj to []

Some related issues addressed during development:

• CLJ-1511
• CLJ-1497
• CLJ-1549
• CLJ-1537
• CLJ-1554
• CLJ-1601
• CLJ-1606
• CLJ-1621
• CLJ-1600
• CLJ-1635
• CLJ-1683
• CLJ-1669
• CLJ-1723

Reader Conditionals are a new capability to support portable code that can run on multiple Clojure platforms with only small changes. In particular, this feature aims to support the increasingly common case of libraries targeting both Clojure and ClojureScript.

Code intended to be common across multiple platforms should use a new supported file extension: ".cljc". When requested to load a namespace, the platform-specific file extension (.clj, .cljs) will be checked prior to .cljc.

A new reader form can be used to specify "reader conditional" code in cljc files (and only cljc files). Each platform defines a feature identifying the platform (:clj, :cljs, :cljr). The reader conditional specifies code that is read conditionally based on the feature. The REPL also allows reader conditionals.

Form #? takes a list of alternating feature and expression. These are checked like cond and the selected expression is read and returned. Other branches are read but skipped. If no branch is selected, the reader reads nothing (not nil, but literally as if reading no form). An optional :default branch can be used as a fallthrough.

Reader conditional with 2 features and a default:

#?(:clj     Double/NaN
   :cljs    js/NaN
   :default nil)

There is also a reader conditional splicing form. The evaluated expression should be sequential and will be spliced into the surrounded code, similar to unquote-splicing.

For example:

[1 2 #?@(:clj [3 4] :cljs [5 6])]

This form would read as [1 2 3 4] on Clojure, [1 2 5 6] on ClojureScript, and [1 2] on any other platform. Splicing is not allowed at the top level.

Additionally, the reader can now be invoked with options for the features to use and how to interpret reader conditionals. By default, reader conditionals are not allowed, but that can be turned on, or a "preserve" mode can be used to preserve all branches (most likely useful for tooling or source transforms).

In the preserve mode, the reader conditional itself and any tagged literals within the unselected branches are returned as tagged literal data.

For more information, see: http://dev.clojure.org/display/design/Reader Conditionals

• CLJ-1424
• CLJ-1685
• CLJ-1698
• CLJ-1699
• CLJ-1700
• CLJ-1728
• CLJ-1706

In response to issues raised in CLJ-1439, several changes have been made in symbol and keyword construction:

1. The main bottleneck in construction of symbols (which also occurs inside keywords) was interning of the name and namespace strings. This interning has been removed, resulting in a performance increase.

2. Keywords are cached and keyword construction includes a cache check. A change was made to only clear the cache reference queue when there is a cache miss.

One source of performance issues is the (unintended) use of arithmetic operations on boxed numbers. To make detecting the presence of boxed math easier, a warning will now be emitted about boxed math if *unchecked-math* is set to :warn-on-boxed (any truthy value will enable unchecked-math, only this specific value enables the warning).

Example use:

user> (defn plus-2 [x] (  x 2))  ;; no warning, but boxed
#'user/plus-2
user> (set! *unchecked-math* :warn-on-boxed)
true
user> (defn plus-2 [x] (  x 2)) ;; now we see a warning
Boxed math warning, NO_SOURCE_PATH:10:18 - call: public static java.lang.Number
clojure.lang.Numbers.unchecked_add(java.lang.Object,long).
#'user/plus-2
user> (defn plus-2 [^long x] (  x 2)) ;; use a hint to avoid boxing
#'user/plus-2

• CLJ-1325
• CLJ-1535
• CLJ-1642

update is a new function that is like update-in specifically for first-level keys:

(update m k f args...)

Example use:

user> (update {:a 1} :a inc)
{:a 2}
user> (update {:a 1} :a   2)
{:a 3}
user> (update {} :a identity)  ;; missing returns nil
{:a nil}

• CLJ-1251

Several important Clojure functions now return sequences that also contain fast reduce() (or in some cases iterator()) paths. In many cases, the new implementations are also faster for lazy sequences

• repeat - now implements IReduce
• cycle - implements IReduceInit
• iterate - implements IReduceInit
• range - implements IReduce, specialized case handles common case of all longs
• keys - iterates directly over the keys of a map, without seq or MapEntry allocation
• vals - iterates directly over the vals of a map, without seq or MapEntry allocation
• iterator-seq - creates a chunked sequence when previously it was unchunked

Additionally, hash-maps and hash-sets now provide iterators that walk the data structure directly rather than via a sequence.

A new interface (IMapIterable) for direct key and val iterators on maps was added. External data structures can use this interface to provide direct key and val iterators via keys and vals.

These enhancements are particularly effective when used in tandem with transducers via transduce, sequence, into, and eduction.

• CLJ-1603
• CLJ-1515
• CLJ-1602
• CLJ-1669
• CLJ-1692
• CLJ-1694
• CLJ-1711
• CLJ-1709
• CLJ-1713
• CLJ-1726
• CLJ-1727

There have been enhancements in how the REPL prints values without a print-method, specifically Throwable and the fallthrough Object case. Both cases now print in a tagged literal data form that can be read by the reader.

Unhandled objects print with the class, hash code, and toString:

user=> *ns*
#object[clojure.lang.Namespace 0x55aa628 "user"]

Thrown exceptions will still be printed in the normal way by the default REPL but printing them to a stream will show a different form:

user=> (/ 1 0)
ArithmeticException Divide by zero  clojure.lang.Numbers.divide (Numbers.java:158)
user=> (println *e)
#error {
 :cause Divide by zero
 :via
 [{:type java.lang.ArithmeticException
   :message Divide by zero
   :at [clojure.lang.Numbers divide Numbers.java 158]}]
 :trace
 [[clojure.lang.Numbers divide Numbers.java 158]
  [clojure.lang.Numbers divide Numbers.java 3808]
  ;; ... elided frames
  ]}

Additionally, there is a new function available to obtain a Throwable as map data: Throwable->map.

• CLJ-1703
• CLJ-1716
• CLJ-1735

run! is a new function that takes a side effect reducing function and runs it for all items in a collection via reduce. The accumulator is ignored and nil is returned.

(run! println (range 10))

• CLJ-1261 Invalid defrecord results in exception attributed to consuming ns instead of defrecord ns
• CLJ-1297 Give more specific hint if namespace with "-" not found to check file uses "_"

• CLJ-1417 clojure.java.io/input-stream has incorrect docstring
• CLJ-1357 Fix typo in gen-class doc-string
• CLJ-1479 Fix typo in filterv example
• CLJ-1480 Fix typo in defmulti docstring
• CLJ-1477 Fix typo in deftype docstring
• CLJ-1478 Fix typo in clojure.main usage
• CLJ-1738 Clarify usage on Java iterators in seq and iterator-seq

• CLJ-1430 Improve performance of partial with more unrolling
• CLJ-1384 clojure.core/set should use transients for better performance
• CLJ-1429 Cache unknown multimethod value default dispatch
• CLJ-1529 Reduce compile times by avoiding unnecessary calls to Class.forName()
• CLJ-1546 vec is now faster on almost all inputs
• CLJ-1618 set is now faster on almost all inputs
• CLJ-1695 Fixed reflection call in variadic vector-of constructor

• CLJ-1191 Improve apropos to show some indication of namespace of symbols found
• CLJ-1378 Hints don't work with #() form of function
• CLJ-1498 Removes owner-thread check from transients - this check was preventing some valid usage of transients in core.async where a transient is created on one thread and then used again in another pooled thread (while still maintaining thread isolation).
• CLJ-803 Extracted IAtom interface implemented by Atom.
• CLJ-1315 Don't initialize classes when importing them
• CLJ-1330 Class name clash between top-level functions and defn'ed ones
• CLJ-1349 Update to latest test.generative and add dependency on test.check
• CLJ-1546 vec now works with things that only implement Iterable or IReduceInit
• CLJ-1618 set now works with things that only implement Iterable or IReduceInit
• CLJ-1633 PersistentList/creator doesn't handle ArraySeqs correctly
• CLJ-1589 Clean up unused paths in InternalReduce
• CLJ-1677 Add setLineNumber() to LineNumberingPushbackReader
• CLJ-1667 Change test to avoid using hard-coded socket port
• CLJ-1683 Change reduce tests to better catch reduce without init bugs

• CLJ-1362 Reduce broken on some primitive vectors
• CLJ-1388 Equality bug on records created with nested calls to map->record
• CLJ-1274 Unable to set compiler options via system properties except for AOT compilation
• CLJ-1241 NPE when AOTing overrided clojure.core functions
• CLJ-1185 reductions does not check for reduced value
• CLJ-1039 Using def with metadata {:type :anything} throws ClassCastException during printing
• CLJ-887 Error when calling primitive functions with destructuring in the arg vector
• CLJ-823 Piping seque into seque can deadlock
• CLJ-738 <= is incorrect when args include Double/NaN
• CLJ-1408 Make cached string value of Keyword and Symbol transient
• CLJ-1466 clojure.core/bean should implement Iterable
• CLJ-1578 Make refer of Clojure core function not throw exception on reload
• CLJ-1501 LazySeq equals() should not use equiv() logic
• CLJ-1572 into (and other fns that rely on reduce) require only IReduceInit
• CLJ-1619 PersistentVector now directly implements reduce without init
• CLJ-1580 Transient collections should guarantee thread visibility
• CLJ-1590 Some IReduce/IReduceInit implementors don't respect reduced
• CLJ-979 Clojure resolves to wrong deftype classes when AOT compiling or reloading
• CLJ-1636 Fix intermittent SeqIterator problem by removing use of this as a sentinel
• CLJ-1637 Fix regression from CLJ-1546 that broke vec on MapEntry
• CLJ-1663 Fix regression from CLJ-979 for DynamicClassLoader classloader delegation
• CLJ-1604 Fix error from AOT'ed code defining a var with a clojure.core symbol name
• CLJ-1561 Fix incorrect line number reporting for error locations
• CLJ-1568 Fix incorrect line number reporting for error locations
• CLJ-1638 Fix regression from CLJ-1546 removed PersistentVector.create(List) method
• CLJ-1681 Fix regression from CLJ-1248 (1.6) in reflection warning with literal nil argument
• CLJ-1648 Use equals() instead of == when resolving Symbol
• CLJ-1195 emit-hinted-impl expands to ns-qualified invocation of fn
• CLJ-1237 reduce of sequence that switches between chunked and unchunked many times throws StackOverflow

Clojure now builds with Java SE 1.6 and emits bytecode requiring Java SE 1.6 instead of Java SE 1.5. [CLJ-1268]

The embedded version of the ASM bytecode library has been upgraded to ASM 4.1. [CLJ-713]

The following features are no longer marked Alpha in Clojure:

• Watches - add-watch, remove-watch
• Transients - transient, persistent!, conj!, assoc!, dissoc!, pop!, disj!
• Exception data - ex-info, ex-data
• Promises - promise, deliver
• Records - defrecord
• Types - deftype
• Pretty-print tables - print-table

The clojure.java.api package provides a minimal interface to bootstrap Clojure access from other JVM languages. It does this by providing:

1. The ability to use Clojure's namespaces to locate an arbitrary var, returning the var's clojure.lang.IFn interface.
2. A convenience method read for reading data using Clojure's edn reader.

IFns provide complete access to Clojure's APIs. You can also access any other library written in Clojure, after adding either its source or compiled form to the classpath.

The public Java API for Clojure consists of the following classes and interfaces:

• clojure.java.api.Clojure
• clojure.lang.IFn

All other Java classes should be treated as implementation details, and applications should avoid relying on them.

To look up and call a Clojure function:

IFn plus = Clojure.var("clojure.core", " ");
plus.invoke(1, 2);

Functions in clojure.core are automatically loaded. Other namespaces can be loaded via require:

IFn require = Clojure.var("clojure.core", "require");
require.invoke(Clojure.read("clojure.set"));

IFns can be passed to higher order functions, e.g. the example below passes plus to read:

IFn map = Clojure.var("clojure.core", "map");
IFn inc = Clojure.var("clojure.core", "inc");
map.invoke(inc, Clojure.read("[1 2 3]"));

Most IFns in Clojure refer to functions. A few, however, refer to non-function data values. To access these, use deref instead of fn:

IFn printLength = Clojure.var("clojure.core", "*print-length*");
Clojure.var("clojure.core", "deref").invoke(printLength);

• CLJ-1318

In the past, map destructuring with :keys and :syms would not work with maps containing namespaced keys or symbols. The :keys and :syms forms have been updated to allow them to match namespaced keys and bind to a local variable based on the name.

Examples:

(let [m {:x/a 1, :y/b 2}
      {:keys [x/a y/b]} m]
  (  a b))

(let [m {'x/a 1, 'y/b 2}
      {:syms [x/a y/b]} m]
  (  a b))

Additionally, the :keys form can now take keywords instead of symbols. This provides support specifically for auto-resolved keywords:

(let [m {:x/a 1, :y/b 2}
      {:keys [:x/a :y/b]} m]
  (  a b))

(let [m {::x 1}
      {:keys [::x]} m]
  x)

Many conditional functions rely on logical truth (where "falsey" values are nil or false). Sometimes it is useful to have functions that rely on "not nilness" instead. These functions have been added to support these cases [CLJ-1343]:

• some? - same as (not (nil? x))
• if-some - like if-let, but checks (some? test) instead of test
• when-some - like when-let, but checks (some? test) instead of test

Clojure 1.6 provides new hashing algorithms for primitives and collections, accessible via IHashEq/hasheq (in Java) or the clojure.core/hash function (in Clojure). In general, these changes should be transparent to users, except hash codes used inside hashed collections like maps and sets will have better properties.

Hash codes returned by the Java .hashCode() method are unchanged and continue to match Java behavior or conform to the Java specification as appropriate.

Any collections implementing IHashEq or wishing to interoperate with Clojure collections should conform to the hashing algorithms specified in http://clojure.org/data_structures#hash and use the new function mix-collection-hash for the final mixing operation. Alternatively, you may call the helper functions hash-ordered-coll and hash-unordered-coll.

Any details of the current hashing algorithm not specified on that page should be considered subject to future change.

Related tickets for dev and regressions:

• CLJ-1328 Make several Clojure tests independent of ordering
• CLJ-1331 Update primitive vectors to use Murmur3 hash
• CLJ-1335 Update hash for empty PersistentList and LazySeq
• CLJ-1336 Make hashing mixing functions available in Clojure
• CLJ-1338 Make Murmur3 class public
• CLJ-1344 Update mapHasheq to call Murmur3 algorithm
• CLJ-1348 Add hash-ordered-coll and hash-unordered-coll
• CLJ-1355 Restore cached hashCode for Symbol and (uncached) hashCode for Keyword
• CLJ-1365 Add type hints for new collection hash functions

• CLJ-827 - unsigned-bit-shift-right

A new unsigned-bit-shift-right (Java's >>>) has been added to the core library. The shift distance is truncated to the least 6 bits (per the Java specification for long >>>).

Examples: (unsigned-bit-shift-right 2r100 1) ;; 2r010 (unsigned-bit-shift-right 2r100 2) ;; 2r001 (unsigned-bit-shift-right 2r100 3) ;; 2r000

• CLJ-866 - test-vars
• CLJ-1352 - fix regression in CLJ-866

Added a new clojure.test/test-vars function that takes a list of vars, groups them by namespace, and runs them with their fixtures.

• CLJ-908 Print metadata for functions when print-meta is true and remove errant space at beginning.
• CLJ-937 pprint cl-format now supports E, F, and G formats for ratios.

• CLJ-1248 Include type information in reflection warning messages
• CLJ-1099 If non-seq passed where seq is needed, error message now is an ExceptionInfo with the instance value, retrievable via ex-data.
• CLJ-1083 Fix error message reporting for "munged" function names (like a->b).
• CLJ-1056 Handle more cases and improve error message for errors in defprotocol definitions.
• CLJ-1102 Better handling of exceptions with empty stack traces.
• CLJ-939 Exceptions thrown in the top level ns form are reported without file or line number.

• CLJ-1164 Fix typos in clojure.instant/validated and other internal instant functions.
• CLJ-1143 Correct doc string for ns macro.
• CLJ-196 Clarify value of file is undefined in the REPL.
• CLJ-1228 Fix a number of spelling errors in namespace and doc strings.
• CLJ-835 Update defmulti doc to clarify expectations for hierarchy argument.
• CLJ-1304 Fix minor typos in documentation and comments
• CLJ-1302 Mention that keys and vals order are consistent with seq order

• CLJ-858 Improve speed of STM by removing System.currentTimeMillis.
• CLJ-669 clojure.java.io/do-copy: use java.nio for Files
• commit Reduce overhead of protocol callsites by removing unneeded generated cache fields.

• CLJ-908 Make default-data-reader-fn set!-able in REPL, similar to data-readers.
• CLJ-783 Make clojure.inspector/inspect-tree work on sets.
• CLJ-896 Make browse-url aware of xdg-open.
• CLJ-1160 Fix clojure.core.reducers/mapcat does not stop on reduced? values.
• CLJ-1121 -> and ->> have been rewritten to work with a broader set of macros.
• CLJ-1105 clojure.walk now supports records.
• CLJ-949 Removed all unnecessary cases of sneakyThrow.
• CLJ-1238 Allow EdnReader to read foo// (matches LispReader behavior).
• CLJ-1264 Remove uses of _ as a var in the Java code (causes warning in Java 8).
• CLJ-394 Add record? predicate.
• CLJ-1200 ArraySeq dead code cleanup, ArraySeq_short support added.
• CLJ-1331 Primitive vectors should implement hasheq and use new hash algorithm
• CLJ-1354 Make APersistentVector.SubVector public so other collections can access
• CLJ-1353 Make awt run headless during the build process

• CLJ-1018 Make range consistently return infinite sequence of start with a step of 0.
• CLJ-863 Make interleave return () on 0 args and identity on 1 args.
• CLJ-1072 Update internal usages of the old metadata reader syntax to new syntax.
• CLJ-1193 Make bigint and biginteger functions work on double values outside long range.
• CLJ-1154 Make Compile.java flush but not close stdout so errors can be reported.
• CLJ-1161 Remove bad version.properties from sources jar.
• CLJ-1175 Fix invalid behavior of Delay/deref if an exception is thrown - exception will now be rethrown on subsequent calls and not enter a corrupted state.
• CLJ-1171 Fix several issues with instance? to make it consistent when used with apply.
• CLJ-1202 Protocol fns with dashes may get incorrectly compiled into field accesses.
• CLJ-850 Add check to emit invokePrim with return type of double or long if type-hinted.
• CLJ-1177 clojure.java.io URL to File coercion corrupts path containing UTF-8 characters.
• CLJ-1234 Accept whitespace in Record and Type reader forms (similar to data literals).
• CLJ-1233 Allow ** as a valid symbol name without triggering dynamic warnings.
• CLJ-1246 Add support to clojure.reflect for classes with annotations.
  • CLJ-1184 Evaling #{do ...} or [do ...] is treated as do special form.
• CLJ-1090 Indirect function calls through Var instances fail to clear locals.
• CLJ-1076 pprint tests fail on Windows, expecting \n.
• CLJ-766 Make into-array work consistently with short-array and byte-array on bigger types.
• CLJ-1285 Data structure invariants are violated after persistent operations when collision node created by transients.
• CLJ-1222 Multiplication overflow issues around Long/MIN_VALUE
• CLJ-1118 Inconsistent numeric comparison semantics between BigDecimals and other numerics
• CLJ-1125 Clojure can leak memory in a servlet container when using dynamic bindings or STM transactions.
• CLJ-1082 Subvecs of primitve vectors cannot be reduced
• CLJ-1301 Case expressions use a mixture of hashCode and hasheq, potentially leading to missed case matches when these differ.
• CLJ-983 proxy-super does not restore original binding if call throws exception
• CLJ-1176 clojure.repl/source errors when read-eval bound to :unknown
• CLJ-935 clojure.string/trim uses different definition of whitespace than triml and trimr
• CLJ-1058 StackOverflowError on exception in reducef for PersistentHashMap fold
• CLJ-1328 Fix some tests in the Clojure test suite to make their names unique and independent of hashing order
• CLJ-1339 Empty primitive vectors throw NPE on .equals with non-vector sequential types
• CLJ-1363 Field access via .- in reflective case does not work
• CLJ-944 Compiler gives constant collections types which mismatch their runtime values
• CLJ-1387 reduce-kv on large hash maps ignores reduced result

• fix for leak caused by ddc65a96fdb1163b

 1 Deprecated and Removed Features
    1.1 Clojure 1.5 reducers library requires Java 6 or later
 2 New and Improved Features
    2.1 Reducers
    2.2 Reader Literals improved
    2.3 clojure.core/set-agent-send-executor!, set-agent-send-off-executor!, and send-via
    2.4 New threading macros
    2.5 Column metadata captured by reader
    2.6 gen-class improvements
    2.7 Support added for marker protocols
    2.8 clojure.pprint/print-table output compatible with Emacs Org mode
    2.9 clojure.string/replace and replace-first handle special characters more predictably
    2.10 Set and map constructor functions allow duplicates
    2.11 More functions preserve metadata
    2.12 New edn reader, improvements to *read-eval*
 3 Performance Enhancements
 4 Improved error messages
 5 Improved documentation strings
 6 Bug Fixes
 7 Binary Compatibility Notes

The new reducers library (see below) requires Java 6 plus a ForkJoin library, or Java 7 or later. Clojure 1.5 can still be compiled and run with Java 5. The only limitations with Java 5 are that the new reducers library will not work, and building Clojure requires skipping the test suite (e.g. by using the command "ant jar").

Reducers provide a set of high performance functions for working with collections. The actual fold/reduce algorithms are specified via the collection being reduced. This allows each collection to define the most efficient way to reduce its contents.

The implementation details of reducers are available at the Clojure blog and therefore won't be repeated in these change notes. However, as a summary:

• There is a new namespace: clojure.core.reducers
• It contains new versions of map, filter etc based upon transforming reducing functions - reducers
• It contains a new function, fold, which is a parallel reduce combine fold uses fork/join when working with (the existing!) Clojure vectors and maps
• Your new parallel code has exactly the same shape as your existing seq-based code
• The reducers are composable
• Reducer implementations are primarily functional - no iterators
• The model uses regular data structures, not 'parallel collections' or other OO malarkey
• It's fast, and can become faster still
• This is work-in-progress

Examples:

user=> (require '[clojure.core.reducers :as r])
user=> (reduce   (r/filter even? (r/map inc [1 1 1 2])))
;=> 6


;;red is a reducer awaiting a collection
user=> (def red (comp (r/filter even?) (r/map inc)))
user=> (reduce   (red [1 1 1 2]))
;=> 6

user=> (into #{} (r/filter even? (r/map inc [1 1 1 2])))
;=> #{2}

• CLJ-1034 "Conflicting data-reader mapping" should no longer be thrown where there really isn't a conflict. Until this patch, having data_readers.clj on the classpath twice would cause the above exception.

• CLJ-927 Added *default-data-reader-fn* to clojure.core. When no data reader is found for a tag and *default-data-reader-fn*is non-nil, it will be called with two arguments, the tag and the value. If *default-data-reader-fn* is nil (the default), an exception will be thrown for the unknown tag.

Added two new functions:

• clojure.core/set-agent-send-executor!

  Allows the user to set the java.util.concurrent.Executor used when calling clojure.core/send. Defaults to a fixed thread pool of size: (numCores 2)

• clojure.core/set-agent-send-off-executor!

  Allows the user to set the java.util.concurrent.Executor used when calling clojure.core/send-off. Defaults to a cached thread pool.

• clojure.core/send-via

  Like send, and send-off, except the first argument to this function is an executor to use when sending.

• clojure.core/cond-> [expr & clauses]

  Takes an expression and a set of test/form pairs. Threads the expression (via ->) through each form for which the corresponding test expression (not threaded) is true.

Example:

user=> (cond-> 1
			   true inc
               false (* 42)
               (= 2 2) (* 3))
6

• clojure.core/cond->> [expr & clauses]

  Takes an expression and a set of test/form pairs. Threads expr (via ->>) through each form for which the corresponding test expression (not threaded) is true.

Example:

user=> (def d [0 1 2 3])
#'user/d
user=> (cond->> d
			    true (map inc)
				(seq? d) (map dec)
				(= (count d) 4) (reduce  )) ;; no threading in the test expr
				                            ;; so d must be passed in explicitly
10

• clojure.core/as-> [expr name & forms]

Binds name to expr, evaluates the first form in the lexical context of that binding, then binds name to that result, repeating for each successive form

Note: this form does not actually perform any threading. Instead it allows the user to assign a name and lexical context to a value created by a parent threading form.

Example:

user=> (-> 84
    	   (/ 4)
    	   (as-> twenty-one          ;; uses the value from ->
           		  (* 2 twenty-one)))  ;; no threading here
42

• clojure.core/some-> [expr & forms]

When expr is not nil, threads it into the first form (via ->), and when that result is not nil, through the next etc.

Example:

user=> (defn die [x] (assert false))
#'user/die
user=> (-> 1 inc range next next next die)
AssertionError Assert failed: false  user/die (NO_SOURCE_FILE:65)
user=> (some-> 1 inc range next next next die)
nil

• clojure.core/some->> [expr & forms]

  When expr is not nil, threads it into the first form (via ->>), and when that result is not nil, through the next etc.

  Same as some-> except the value is threaded as the last argument in each form.

• CLJ-960 Data read by the clojure reader is now tagged with :column in addition to :line.

• CLJ-745 It is now possible to expose protected final methods via :exposes-methods in gen-class. This allows Clojure classes created via gen-class to access protected methods of its parent class.

Example:

(gen-class :name clojure.test_clojure.genclass.examples.ProtectedFinalTester
	       :extends java.lang.ClassLoader
    	   :main false
       	   :prefix "pf-"
       	   :exposes-methods {findSystemClass superFindSystemClass})

• CLJ-948 It is now possible to annotate constructors via gen-class.

Example:

(gen-class :name foo.Bar
	       :extends clojure.lang.Box
    	   :constructors {^{Deprecated true} [Object] [Object]}
       	   :init init
       	   :prefix "foo")

• CLJ-966 defprotocol no longer requires that at least one method be given in the definition of the protocol. This allows for marker protocols, whose sole reason of existence is to allow satisfies? to be true for a given type.

Example:

user=> (defprotocol P (hi [_]))
P
user=> (defprotocol M) ; marker protocol
M
user=> (deftype T [a] M P (hi [_] "hi there"))
user.T
user=> (satisfies? P (T. 1))
true
user=> (satisfies? M (T. 1))
true
user=> (hi (T. 1))
"hi there"
user=> (defprotocol M2 "marker for 2") ; marker protocol again
M2
user=> (extend-type T M2)
nil
user=> (satisfies? M2 (T. 1))
true

For the convenience of those that use Emacs Org mode, clojure.pprint/print-table now prints tables in the form used by that mode. Emacs Org mode has features to make it easy to edit such tables, and even to do spreadsheet-like calculations on their contents. See the Org mode documentation on tables for details.

user=> (clojure.pprint/print-table [:name :initial-impression]
           [{:name "Rich" :initial-impression "rock star"}
            {:name "Andy" :initial-impression "engineer"}])
| :name | :initial-impression |
|------- ---------------------|
|  Rich |           rock star |
|  Andy |            engineer |

clojure.string/replace and clojure.string/replace-first are now consistent in the way that they handle the replacement strings: all characters in the replacement strings are treated literally, including backslash and dollar sign characters.

user=> (require '[clojure.string :as s])

user=> (s/replace-first "munge.this" "." "$")
;=> "munge$this"

user=> (s/replace "/my/home/dir" #"/" (fn [s] "\\"))
;=> "\\my\\home\\dir"

There is one exception, which is described in the doc strings. If you call these functions with a regex to search for and a string as the replacement, then dollar sign and backslash characters in the replacement string are treated specially. Occurrences of $1 in the replacement string are replaced with the string that matched the first parenthesized subexpression of the regex, occurrences of $2 are replaced with the match of the second parenthesized subexpression, etc.

user=> (s/replace "x12, b4" #"([a-z] )([0-9] )" "$1 <- $2")
;=> "x <- 12, b <- 4"

Individual occurrences of $ or \ in the replacement string that you wish to be treated literally can be escaped by prefixing them with a \. If you wish your replacement string to be treated literally and its contents are unknown to you at compile time (or you don't wish to tarnish your constant string with lots of backslashes), you can use the new function clojure.string/re-quote-replacement to do the necessary escaping of special characters for you.

user=> (s/replace "x12, b4" #"([a-z] )([0-9] )"
                     (s/re-quote-replacement "$1 <- $2"))
;=> "$1 <- $2, $1 <- $2"

All of the functions that construct sets such as set and sorted-set allow duplicate elements to appear in their arguments, and they are documented to treat this case as if by repeated uses of conj.

Similarly, all map constructor functions such as hash-map, array-map, and sorted-map allow duplicate keys, and are documented to treat this case as if by repeated uses of assoc.

As before, literal sets, e.g. #{1 2 3}, do not allow duplicate elements, and while elements can be expressions evaluated at run time such as #{(inc x) (dec y)}, this leads to a check for duplicates at run time whenever the set needs to be constructed, throwing an exception if any duplicates are found.

Similarly, literal maps do not allow duplicate keys. New to Clojure 1.5 is a performance optimization: if all keys are compile time constants but one or more values are expressions requiring evaluation at run time, duplicate keys are checked for once at compile time only, not each time a map is constructed at run time.

• CLJ-1065 Allow duplicate set elements and map keys for all set and map constructors

Most functions that take a collection and return a "modified" version of that collection preserve the metadata that was on the input collection, e.g. conj, assoc, dissoc, etc. One notable exception was into, which would return a collection with metadata nil for several common types of input collections.

Now the functions into, select-keys, clojure.set/project, and clojure.set/rename return collections with the same metadata as their input collections.

The new clojure.edn namespace reads edn (http://edn-format.org) data, and should be used for reading data from untrusted sources.

Clojure's core read* functions can evaluate code, and should not be used to read data from untrusted sources. As of 1.5, *read-eval* supports a documented set of thread-local bindings, see the doc string for details.

*read-eval*'s default can be set to false by setting a system property:

-Dclojure.read.eval=false

• CLJ-988 Multimethod tables are now protected by a read/write lock instead of a synchronized method. This should result in a performance boost for multithreaded code using multimethods.
• CLJ-1061 when-first now evaluates its expression only once.
• CLJ-1084 PersistentVector$ChunkedSeq now implements Counted interface, to avoid some cases where vector elements were being counted by iterating over their elements.
• CLJ-867 Records with same fields and field values, but different types, now usually hash to different values.
• CLJ-1000 Cache hasheq() for seqs, sets, vectors, maps and queues
• (no ticket) array-map perf tweaks
• CLJ-1111 Allows loop to evaluate to primitive values
• (no ticket) Move loop locals into same clearing context as loop body

• CLJ-103 Improved if-let error message when form has a improperly defined body.
• CLJ-897 Don't use destructuring in defrecord/deftype arglists to get a slightly better error message when forgetting to specify the fields vector
• CLJ-788 Add source and line members and getters to CompilerException
• CLJ-157 Better error messages for syntax errors w/ defn and fn
• CLJ-940 Passing a non-sequence to refer :only results in uninformative exception
• CLJ-1052 assoc now throws an exception if the last key argument is missing a value.

• CLJ-893 Document that vec will alias Java arrays
• CLJ-892 Clarify doc strings of sort and sort-by: they will modify Java array arguments
• CLJ-1019 ns-resolve doc has a typo
• CLJ-1038 Docstring for deliver doesn't match behavior
• CLJ-1055 "be come" should be "become"
• CLJ-917 clojure.core/definterface is not included in the API docs
• (no ticket) clojure.core/read, read-string, and read-eval all have more extensive documentation.

• CLJ-962 Vectors returned by subvec allow access at negative indices
• CLJ-952 bigdec does not properly convert a clojure.lang.BigInt
• CLJ-975 inconsistent destructuring behaviour when using nested maps
• CLJ-954 TAP support in clojure.test.tap Needs Updating
• CLJ-881 exception when cl-format is given some ~f directive/value combinations
• CLJ-763 Do not check for duplicates in destructuring map creation
• CLJ-667 Allow loops fully nested in catch/finally
• CLJ-768 cl-format bug in ~f formatting
• CLJ-844 NPE calling keyword on map from bean
• CLJ-934 disj! Throws exception when attempting to remove multiple items in one call
• CLJ-943 When load-lib fails, a namespace is still created
• CLJ-981 clojure.set/rename-keys deletes keys when there's a collision
• CLJ-961 with-redefs loses a Var's root binding if the Var is thread-bound
• CLJ-1032 seque leaks threads from the send-off pool
• CLJ-1041 reduce-kv on sorted maps should stop on seeing a Reduced value
• CLJ-1011 clojure.data/diff should cope with null and false values in maps
• CLJ-977 (int \a) returns a value, (long \a) throws an exception
• CLJ-964 test-clojure/rt.clj has undeclared dependency on clojure.set
• CLJ-923 Reading ratios prefixed by is not working
• CLJ-1012 partial function should also accept 1 arg (just f)
• CLJ-932 contains? Should throw exception on non-keyed collections
• CLJ-730 Create test suite for functional fns (e.g. juxt, comp, partial, etc.)
• CLJ-757 Empty transient maps/sets return wrong value for .contains
• CLJ-828 clojure.core/bases returns a cons when passed a class and a Java array when passed an interface
• CLJ-1062 CLJ-940 breaks compilation of namespaces that don't have any public functions
• CLJ-1070 PersistentQueue's hash function does not match its equality
• CLJ-987 pprint doesn't flush the underlying stream
• CLJ-963 Support pretty printing namespace declarations under code-dispatch
• CLJ-902 doc macro broken for namespaces
• CLJ-909 Make LineNumberingPushbackReader's buffer size configurable
• CLJ-910 Allow for type-hinting the method receiver in memfn
• CLJ-1048 add test.generative to Clojure's tests
• CLJ-1071 ExceptionInfo does no abstraction
• CLJ-1085 clojure.main/repl unconditionally refers REPL utilities into *ns*
• (no ticket) Rich Hickey fix: syntax-quote was walking records, returning maps
• CLJ-1116 More REPL-friendly 'ns macro
• (no ticket) Rich Hickey fix: deref any j.u.c.Future
• CLJ-1092 New function re-quote-replacement has incorrect :added metadata
• CLJ-1098 Implement IKVReduce and CollFold for nil
• (no ticket) Rich Hickey fix: impose once semantics on fabricated closures for e.g. loops
• CLJ-1140 Restore {:as x} destructuring for empty lists
• CLJ-1150 Make some PersistentVector's and APersistentVector.SubVector's internals public
• (no ticket) Rich Hickey fix: use non-loading classForName
• CLJ-1106 Fixing set equality

• public static inner class LispReader.ReaderException(int line, Throwable cause) Constructor changed to ReaderException(int line, int column, Throwable cause)
• public Object clojure.lang.Agent.dispatch(IFn fn, ISeq args, boolean solo) Replaced with dispatch(IFn fn, ISeq args, Executor exec)

 1 Deprecated and Removed Features
    1.1 Fields that Start With a Dash Can No Longer Be Accessed Using Dot Syntax
 2 New/Improved Features
    2.1 Reader Literals
    2.2 clojure.core/mapv
    2.3 clojure.core/filterv
    2.4 clojure.core/ex-info and clojure.core/ex-data
    2.5 clojure.core/reduce-kv
    2.6 clojure.core/contains? Improved
    2.7 clojure.core/min and clojure.core/max prefer NaN
    2.8 clojure.java.io/as-file and clojure.java.io/as-url Handle URL-Escaping Better
    2.9 New Dot Syntax for Record and Type Field Access
    2.10 Record Factory Methods Available Inside defrecord
    2.11 assert-args Displays Namespace and Line Number on Errors
    2.12 File and Line Number Added to Earmuff Dynamic Warning
    2.13 require Can Take a :refer Option
    2.14 *compiler-options* Var
    2.15 Improved Reporting of Invalid Characters in Unicode String Literals
    2.16 clojure.core/hash No Longer Relies on .hashCode
    2.17 Java 7 Documentation
    2.18 loadLibrary Loads Library Using System ClassLoader
    2.19 Java int is boxed as java.lang.Integer
 3 Performance Enhancements
 4 Bug Fixes

Clojure 1.4 introduces a field accessor syntax for the dot special form that aligns Clojure field lookup syntax with ClojureScript's.

For example, in Clojure 1.3, one can declare a record with a field starting with dash and access it like this:

(defrecord Bar [-a]) ;=> user.Bar
(.-a (Bar. 10)) ;=> 10

In 1.4, the above code results in IllegalArgumentException No matching field found: a for class user.Bar

However, the field may still be accessed as a keyword:

(:-a (Bar. 10)) ;=> 10

Clojure 1.4 supports reader literals, which are data structures tagged by a symbol to denote how they will be read.

When Clojure starts, it searches for files named data_readers.clj at the root of the classpath. Each such file must contain a Clojure map of symbols, like this:

{foo/bar my.project.foo/bar
 foo/baz my.project/baz}

The key in each pair is a tag that will be recognized by the Clojure reader. The value in the pair is the fully-qualified name of a Var which will be invoked by the reader to parse the form following the tag. For example, given the data_readers.clj file above, the Clojure reader would parse this form:

#foo/bar [1 2 3]

by invoking the Var #'my.project.foo/bar on the vector [1 2 3]. The data reader function is invoked on the form AFTER it has been read as a normal Clojure data structure by the reader.

Reader tags without namespace qualifiers are reserved for Clojure. Default reader tags are defined in clojure.core/default-data-readers but may be overridden in data_readers.clj or by rebinding *data-readers*.

Clojure supports literals for instants in the form #inst "yyyy-mm-ddThh:mm:ss.fff hh:mm". These literals are parsed as java.util.Dates by default. They can be parsed as java.util.Calendars or java.util.Timestamps by binding *data-readers* to use clojure.instant/read-instant-calendar or clojure.instant/read-instant-timestamp.

(def instant "#inst \"@2010-11-12T13:14:15.666\"")

; Instants are read as java.util.Date by default
(= java.util.Date (class (read-string instant)))
;=> true

; Instants can be read as java.util.Calendar or java.util.Timestamp

(binding [*data-readers* {'inst read-instant-calendar}]
  (= java.util.Calendar (class (read-string instant))))
;=> true

(binding [*data-readers* {'inst read-instant-timestamp}]
  (= java.util.Timestamp (class (read-string instant))))
;=> true

Clojure supports literals for UUIDs in the form #uuid "uuid-string". These literals are parsed as java.util.UUIDs.

mapv takes a function f and one or more collections and returns a vector consisting of the result of applying f to the set of first items of each collection, followed by applying f to the set of second items in each collection, until any one of the collections is exhausted. Any remaining items in other collections are ignored. f should accept a number of arguments equal to the number of collections.

(= [1 2 3] (mapv   [1 2 3]))
;=> true

(= [2 3 4] (mapv   [1 2 3] (repeat 1)))
;=> true

filterv takes a predicate pred and a collection and returns a vector of the items in the collection for which (pred item) returns true. pred must be free of side-effects.

(= [] (filterv even? [1 3 5]))
;=> true

(= [2 4] (filterv even? [1 2 3 4 5]))
;=> true

ex-info creates an instance of ExceptionInfo. ExceptionInfo is a RuntimeException subclass that takes a string msg and a map of data.

(ex-info "Invalid use of robots" {:robots false})
;=> #<ExceptionInfo clojure.lang.ExceptionInfo: Invalid use of robots {:robots false}>

ex-data is called with an exception and will retrieve that map of data if the exception is an instance of ExceptionInfo.

(ex-data (ex-info "Invalid use of robots" {:robots false}))
;=> {:robots false}

reduce-kv reduces an associative collection. It takes a function f, an initial value init and an associative collection coll. f should be a function of 3 arguments. Returns the result of applying f to init, the first key and the first value in coll, then applying f to that result and the 2nd key and value, etc. If coll contains no entries, returns init and f is not called. Note that reduce-kv is supported on vectors, where the keys will be the ordinals.

(reduce-kv str "Hello " {:w \o :r \l :d \!})
;=> "Hello :rl:d!:wo"
(reduce-kv str "Hello " [\w \o \r \l \d \!])
;=> "Hello 0w1o2r3l4d5!"

contains? now works with java.util.Set.

min and max now give preference to returning NaN if either of their arguments is NaN.

as-file and as-url now handle URL-escaping in both directions.

Clojure 1.4 introduces a field accessor syntax for the dot special form that aligns Clojure field lookup syntax with ClojureScript's.

In 1.4, to declare a record type and access its property x, one can write:

(defrecord Foo [x]) ;=> user.Foo
(.-x (Foo. 10)) ;=> 10

This addition makes it easier to write code that will run as expected in both Clojure and ClojureScript.

Prior to 1.4, you could not use the factory functions (->RecordClass and map->RecordClass) to construct a new record from inside a defrecord definition.

The following example did not work prior to 1.4, but is now valid. This example makes use of ->Mean which would have not yet been available.

(defrecord Mean [last-winner]
  Player
  (choose [_] (if last-winner last-winner (random-choice)))
  (update-strategy [_ me you] (->Mean (when (iwon? me you) me))))

assert-args now uses &form to report the namespace and line number where macro syntax errors occur.

When a variable is defined using earmuffs but is not declared dynamic, Clojure emits a warning. That warning now includes the file and line number.

require can now take a :refer option. :refer takes a list of symbols to refer from the namespace or :all to bring in all public vars.

The dynamic var *compiler-options* contains a map of options to send to the Clojure compiler.

Supported options:

• :elide-meta: Have certain metadata elided during compilation. This should be set to a collection of keywords.
• :disable-locals-clearing: Set to true to disable clearing. Useful for using a debugger.

The main function of the Clojure compiler sets the *compiler-options* from properties prefixed by clojure.compiler, e.g.

java -Dclojure.compiler.elide-meta='[:doc :file :line]'

When the reader finds an invalid character in a Unicode string literal, it now reports the character instead of its numerical representation.

hash no longer directly uses .hashCode() to return the hash of a Clojure data structure. It calls clojure.lang.Util.hasheq, which has its own implementation for Integer, Short, Byte, and Clojure collections. This ensures that the hash code returned is consistent with =.

*core-java-api* will now return the URL for the Java 7 Javadoc when you are running Java 7.

A static method, loadLibrary, was added to clojure.lang.RT to load a library using the system ClassLoader instead of Clojure's class loader.

Java ints are now boxed as java.lang.Integers. See the discussion on clojure-dev for more information.

• (= char char) is now optimized
• equiv is inlined in variadic =
• toString cached on keywords and symbols

• CLJ-829 Transient hashmaps mishandle hash collisions
• CLJ-773 Macros that are expanded away still have their vars referenced in the emitted byte code
• CLJ-837 java.lang.VerifyError when compiling deftype or defrecord with argument name starting with double underscore characters
• CLJ-369 Check for invalid interface method names
• CLJ-845 Unexpected interaction between protocol extension and namespaced method keyword/symbols
  • Ignoring namespace portion of symbols used to name methods in extend-type and extend-protocol
• CLJ-852 IllegalArgumentException thrown when defining a var whose value is calculated with a primitive fn
• CLJ-855 catch receives a RuntimeException rather than the expected checked exception
• CLJ-876 #^:dynamic vars declared in a nested form are not immediately dynamic
• CLJ-886 java.io/do-copy can garble multibyte characters
• CLJ-895 Collection.toArray implementations do not conform to Java API docs
  • obey contract for toArray return type
• CLJ-898 Agent sends consume heap
  • Only capture a shallow copy of the current Frame in binding-conveyor-fn, so that sends in agent actions don't build infinite Frame stacks
• CLJ-928 Instant literal for Date and Timestamp should print in UTC
• CLJ-931 Syntactically broken clojure.test/are tests succeed
• CLJ-933 Compiler warning on clojure.test-clojure.require-scratch

 1 Deprecated and Removed Features
    1.1 Earmuffed Vars are No Longer Automatically Considered Dynamic
    1.2 ISeq No Longer Inherits from Sequential
    1.3 Removed Bit Operation Support for Boxed Numbers
    1.4 Ancillary Namespaces No Longer Auto-Load on Startup
    1.5 Replicate Deprecated
 2 New/Improved Features
    2.1 Enhanced Primitive Support
    2.2 defrecord and deftype Improvements
    2.3 Better Exception Reporting
    2.4 clojure.reflect/reflect
    2.5 clojure.data/diff
    2.6 clojure.core/every-pred and clojure.core/some-fn Combinators
    2.7 clojure.core/realized?
    2.8 clojure.core/with-redefs-fn & with-redefs
    2.9 clojure.core/find-keyword
    2.10 clojure.repl/pst
    2.11 clojure.pprint/print-table
    2.12 pprint respects *print-length*
    2.13 compilation and deployment via Maven
    2.14 internal keyword map uses weak refs
    2.15 ^:const defs
    2.16 Message Bearing Assert
    2.17 Error Checking for defmulti Options
    2.18 Removed Checked Exceptions
    2.19 vector-of Takes Multiple Arguments
    2.20 deref with timeout
    2.21 Walk Support for sorted-by Collections
    2.22 string.join Enhanced to Work with Sets
    2.23 clojure.test-helper
    2.24 Newline outputs platform-specific newline sequence
    2.25 init-proxy and update-proxy return proxy
    2.26 doc & find-doc moved to REPL
    2.27 clojure.java.shell/sh accepts as input anything that clojure.java.io/copy does
    2.28 InterruptedHandler Promoted to clojure.repl
    2.29 Add support for running -main namespaces from clojure.main
    2.30 Set thread names on agent thread pools
    2.31 Add docstring support to def
    2.32 Comp function returns identity when called with zero arity
    2.33 Type hints can be applied to arg vectors
    2.34 Binding Conveyance
 3 Performance Enhancements
 4 Bug Fixes
 5 Modular Contrib

(def *fred*)
=> Warning: *fred* not declared dynamic and thus is not dynamically rebindable, but its name suggests otherwise. Please either indicate ^:dynamic ** or change the name.

This allows ISeq implementers to be in the map or set equality partition.

Bit Operations map directly to primitive operations

The following namespaces are no longer loaded on startup: clojure.set, clojure.xml, clojure.zip

Use repeat instead.

Full details here:

• Enhanced Primitive Support
• Documentation for 1.3 Numerics

Details here: Defrecord Improvements

Details here: Error Handling

Additionally:

Better error messages:

• When calling macros with arity
• For Invalid Map Literals
• For alias function if using unknown namespace
• In the REPL
• Add "starting at " to EOF while reading exceptions
• Better compilation error reporting

Full details here: Reflection API

Recursively compares a and b, returning a tuple of [things-only-in-a things-only-in-b things-in-both]

(diff {:a 1 :b 2} {:a 1 :b 22 :c 3})
=> ({:b 2} {:c 3, :b 22} {:a 1})

every-pred takes a set of predicates and returns a function f that returns true if all of its composing predicates return a logical true value against all of its arguments, else it returns false.

((every-pred even?) 2 4 6)
=> true

((every-pred even?) 2 4 5)
=>false

some-fn takes a set of predicates and returns a function f that returns the first logical true value returned by one of its composing predicates against any of its arguments, else it returns logical false.

((some-fn even?) 2 4 5)
=> true
((some-fn odd?) 2 4 6)
=> false

Returns true if a value has been produced for a promise, delay, future or lazy sequence.

(let [x (range 5)]
  (println (realized? x))
  (first x)
  (println (realized? x)))
=> false
=> true

with-redefs-fn temporarily redefines Vars during a call to func. with-redefs temporarily redefines Vars while executing the body.

(with-redefs [nil? :temp] (println nil?))
=> :temp

Returns a Keyword with the given namespace and name if one already exists.

(find-keyword "def")
=> :def
(find-keyword "fred")
=> nil

Prints a stack trace of the exception

(pst (IllegalArgumentException.))

IllegalArgumentException
    user/eval27 (NO_SOURCE_FILE:18)
    clojure.lang.Compiler.eval (Compiler.java:6355)
    clojure.lang.Compiler.eval (Compiler.java:6322)
    clojure.core/eval (core.clj:2699)
    clojure.main/repl/read-eval-print--5906 (main.clj:244)
    clojure.main/repl/fn--5911 (main.clj:265)
    clojure.main/repl (main.clj:265)
    clojure.main/repl-opt (main.clj:331)
    clojure.main/main (main.clj:427)
    clojure.lang.Var.invoke (Var.java:397)
    clojure.lang.Var.applyTo (Var.java:518)
    clojure.main.main (main.java:37)

Prints a collection of maps in a textual table.

(print-table [:fred :barney]
             [{:fred "ethel"}
              {:fred "wilma" :barney "betty"}])

===============
:fred | :barney
===============
ethel |
wilma | betty
===============

Assigning *print-length* now affects output of pprint

See the following pages for more information:

• Maven Settings and Repositories
• Why Maven?
• Common Contrib Build
• How to Make Releases

^:const lets you name primitive values with speedier reference.

(def constants
 {:pi 3.14
  :e 2.71})

(def ^:const pi (:pi constants))
(def ^:const e (:e constants))

The overhead of looking up :e and :pi in the map happens at compile time, as (:pi constants) and (:e constants) are evaluated when their parent def forms are evaluated.

Assert can take a second argument which will be printed when the assert fails

(assert (= 1 2) "1 is not equal to 2")
=> AssertionError Assert failed: 1 is not equal to 2

defmulti will check to verify that its options are valid. For example, the following code will throw an exception:

(defmulti fred :ethel :lucy :ricky)
=> IllegalArgumentException

Clojure does not throw checked exceptions

vector-of takes multiple args used to populate the array

(vector-of :int 1 2 3)
=> [1 2 3]

deref now takes a timeout option - when given with a blocking reference, will return the timeout-val if the timeout (in milliseconds) is reached before value is available.

(deref (promise) 10 :ethel)
=> :ethel

Walk modified to work on sorted-by collections

let [x (sorted-set-by > 1 2 3)] (walk inc reverse x))
=> (2 3 4)

Just like join works on other collections

(join " and " #{:fred :ethel :lucy})
=> ":lucy and :fred and :ethel"

All test helpers moved into clojure.test-helper

Newline sequence is output as \r\n on Windows now.

Now you can chain calls on the proxy

Adds special form docs to the REPL

This adds InputStream, Reader, File, byte[] to the list of inputs for clojure.java.shell/sh

Promoting this library eliminates the need for a dependency on old contrib.

This patch allows clojure.main to accept an argument pointing to a namespace to look for a -main function in. This allows users to write -main functions that will work the same whether the code is AOT-compiled for use in an executable jar or just run from source.

It's a best practice to name the threads in an executor thread pool with a custom ThreadFactory so that the purpose of these threads is clear in thread dumps and other runtime operational tools.

Patch causes thread names like:

clojure-agent-send-pool-%d     (should be fixed # of threads)
clojure-agent-send-off-pool-%d (will be added and removed over time)

A def can now have a docstring between name and value.

(def foo "a foo" :foo)

(= (comp) identity)
=> true

You can hint different arities separately:

(defn hinted
  (^String [])
  (^Integer [a])
  (^java.util.List [a & args]))

This is preferred over hinting the function name. Hinting the function name is still allowed for backward compatibility, but will likely be deprecated in a future release.

Clojure APIs that pass work off to other threads (e.g. send, send-off, pmap, future) now convey the dynamic bindings of the calling thread:

(def ^:dynamic *num* 1)
(binding [*num* 2] (future (println *num*)))
;; prints "2", not "1"

• Code path for using vars is now much faster for the common case
• Improved startup time
• Fix performance on some numeric overloads See CLJ-380 for more information
• Promises are lock free
• Functions only get metadata support code when metadata explicitly supplied
• definterface/gen-interface accepts array type hints
• inline nil?
• inline bit-functions & math ops
• inline n-ary min & max
• PersistentQueue count is now O(1)
• Intrinsics: unchecked math operators now emit bytecodes directly where possible

Complete list of Tickets for 1.3 Release.

• CLJ-8 detect and report cyclic load dependencies

  • Patch restore detection of cyclic load dependencies

• CLJ-31 compiler now correctly rejects attempts to recur across try (fn [x] (try (recur 1))) => CompilerException

• CLJ-286 *out* being used as java.io.PrintWriter

  • Patch fixes using Writer instead of PrintWriter
  • fix clojure.main to not assume that err is a PrintWriter

• CLJ-292 LazySeq.sval() nests RuntimeExceptions

  • Patch causes only the original RuntimeException to be thrown

• CLJ-390 sends from agent error-handlers should be allowed

  • Patch allows agent error-handler to send successfully

• CLJ-426 case should handle hash collision

  • There were situations where a hash collision would occur with case and an exception would be thrown. See discussion for more details

• CLJ-430 clojure.java.io URL Coercion throws java.lang.ClassCastException

  • Patch correct exception to be thrown

• CLJ-432 deftype does not work if containing ns contains dashes

  • Patch munges namespaces with dashes properly

• CLJ-433 munge should not munge $ (which isJavaIdentifierPart), should munge ' (which is not)

• CLJ-435 stackoverflow exception in printing meta with :type

  • Patch fixes exception being thrown on certain type metadata (with-meta {:value 2} {:type Object}) => No message. [Thrown class java.lang.StackOverflowError]

• CLJ-437 Bugs in clojure.set/subset? and superset? for sets with false/nil elements

  • Patch fixes failing on subset? and superset? for sets with false/nil elements

• CLJ-439 Automatic type translation from Integer to Long

  • Patch fixes increase coercion from Integer to Long

• CLJ-444 Infinite recursion in Keyword.intern leads to stack overflow

  • No more infinite recursion with patch

• CLJ-673 use system class loader when base loader is null

  • facilitates placing Clojure on bootclasspath

• CLJ-678 into-array should work with all primitive types

• CLJ-680 printing promises should not block

  • Patch allows printing of promises without blocking

• CLJ-682 cl-format: ~w throws an exception when not wrapped in a pretty-writer

  • Patch fixes the following bug in cl-format with ~w:

• CLJ-693 VerifyError with symbol metadata, macros, and defrecord

• CLJ-702 case gives NPE when used with nil

  • Patch allows nil to be used with case

• CLJ-734 starting scope of let bindings seems incorrect from jdi perspective

  • Patch fixes local variables table to have the correct code index for let bindings.

• CLJ-739 version.properties file is not closed

  • Patch properly closes version.properties file

• CLJ-751 cl-format: ~( throws an exception with an empty string

  • Patch fixes the following bug in cl-format when format is nil (cl-format nil "~:(a)" "") => NullPointerException

• CLJ-780 race condition in reference cache on Java 5

  • Map.Entry instances can have null values prior to Java 6. This patch provides a workaround.

• floats were being boxed as Doubles, now they are boxed as Floats

• several "holding onto head" fixes

  • Stop top-level defs from hanging onto the head of an expression that uses a lazy seq
  • Stop multimethods from holding onto heads of their arguments

In 1.3, the monolithic clojure-contrib.jar has been replaced by a modular system of contrib libraries, so that production systems can include only the code they actually need. This also allows individual contribs to have their own release cycles. Many contribs have moved forward by several point versions already. Documentation for updating applications to use the new contrib libraries is at http://dev.clojure.org/display/design/Where Did Clojure.Contrib Go

Important Note: Many of the new modular contribs are compatible with both 1.2 and 1.3. This offers an incremental migration path: First, upgrade your contrib libraries while holding Clojure at 1.2, Then, in a separate step, upgrade to Clojure 1.3.