Keywords

Language summary keywords

Most Ada “keywords” have different functions depending on where they are used. A good example is for which controls the representation clause when used within a declaration part and controls a loop when used within an implementation.

In Ada, a keyword is a reserved word, so it cannot be used as an identifier. Some of them are used as attribute names.

List of keywords

Ada Keywords
`abort`	`else`	`new`	`return`
`abs`	`elsif`	`not`	`reverse`
`abstract` (Ada 95)	`end`	`null`
`accept`	`entry`		`select`
`access`	`exception`	`of`	`separate`
`aliased` (Ada 95)	`exit`	`or`	`some` (Ada 2012)
`all`		`others`	`subtype`
`and`	`for`	`out`	`synchronized` (Ada 2005)
`array`	`function`	`overriding` (Ada 2005)
`at`			`tagged` (Ada 95)
	`generic`	`package`	`task`
`begin`	`goto`	`parallel` (Ada 2022)	`terminate`
`body`		`pragma`	`then`
	`if`	`private`	`type`
`case`	`in`	`procedure`
`constant`	`interface` (Ada 2005)	`protected` (Ada 95)	`until` (Ada 95)
	`is`		`use`
`declare`		`raise`
`delay`	`limited`	`range`	`when`
`delta`	`loop`	`record`	`while`
`digits`		`rem`	`with`
`do`	`mod`	`renames`
		`requeue` (Ada 95)	`xor`

Keywords: abort

abort

The abort is used to abort either a task (thread) or partition (process).

Keywords: abs

This keyword is used for the operator that gets the absolute value of a number.

y := abs x;

Keywords: abstract

Summary

The keyword abstract is used to define an abstract tagged type. See Ada Programming/Object Orientation for details on object orientation in Ada.

Keywords: accept

Summary

The keyword accept is used in Ada tasks for accepting a rendezvous.

Keywords: access

This keyword is used in access types declarations and anonymous access parameters.

Keywords: aliased

Description

If you come from C/C you are probably used to the fact that every element of an array, struct/record and other variables has an address. The C/C standards actually demand that. In Ada this is not true.

Ada is a self optimizing language — there is for example no register keyword like in C/C . Ada compilers will use a register for storage automatically. Incidentally, most C/C compilers nowadays just ignore the register and allocate registers themselves, just like Ada does.

So if you want to take an access from any variable you need to tell the compiler that the variable needs to be in memory and may not reside inside a register. This is what the keyword aliased is for. Additionally it also serves as a hint to the reader of the program about the existence of pointers referencing the variable.

For variables

I : aliased Integer := 0;

For type declarations

For the elements of an array

Declaring an array as aliased will only ensure that the array as a whole has an address. It says nothing about the individual elements of the array — which may be packed in a way that more than one element has the same address. You need to declare the actual elements as aliased as well. You can read in Types/array how this is done. Here is just a short example:

 type Day_Of_Month is range 1 .. 31;
 type Day_Has_Appointment is array (Day_Of_Month) of aliased Boolean;

For the elements of a record

Just like arrays, declaring a record as aliased will only ensure that the record as a whole has an address. It says nothing about the individual elements of the record — which again may be packed and share addresses. Again you need to declare the actual elements as aliased as well. You can read in Types/record how this is done. Here is just a short example:

type Basic_Record is
   record
      A : aliased Integer;
   end record;

Keywords: all

This keyword is used in:

Keywords: and

Logical operator

Boolean operator

X : Boolean := A > 10 and A < 20;

Boolean shortcut operator

Shortcut operators are used to make the evaluation of parts of boolean expressions conditional: and then, or else. This should never be done to speed up the evaluation (with modern optimizing compilers, it will possibly not have that effect). The correct use is to prevent the evaluation of expressions known to raise an exception.

if Dog /= null and then G (Dog) then
   Walk (Dog);
end if;

In the example above, G (Dog) is only called when the pointer Dog is not null, i.e. it actually points to something.

Actually and then and or else are not operators in the sense of the reference manual, they are called 'Short-circuit Control Forms'. The difference is that (true) operators can be redefined (i.e. overloaded), whereas these cannot. They are however defined for any boolean type.

Since Ada allows parallel evaluation of the arguments for an expression, shortcut operators are not the standard way of evaluating boolean expressions. In any case where the final result of the evaluation is guaranteed to be the same, the compiler is allowed to use a shortcut evaluation.

Boolean operator on arrays

The and operator is applied to each pair of boolean elements from the left and right arrays. The result has the same bounds as the left operand.

type Day_Of_Month is range 1 .. 31;            
type Month_Array is array (Day_Of_Month) of Boolean;

X : Month_Array := Function_1;
Y : Month_Array := Function_2;
Z : Month_Array := X and Y;

Bitwise operator

The operator and could be used with modular types to perform bitwise operations.

Adding interfaces to tagged types

This language feature is only available from Ada 2005 on.

type Programmer is new Person 
                   and Printable
with 
   record
     Skilled_In : Language_List;
   end record;

Keywords: array

This keyword is used in the declaration of array types and anonymous array objects.

Keywords: at

This keyword is used in representation clauses:

in an alignment clause (obsolescent), replaced by the aspect Alignment;
in a component clause.

and in address clauses (obsolencent), replaced by the aspect Address.

Keywords: begin

The begin keyword in Ada is almost synonymous with the { in C/C /Java. In the paradigm of structured programming languages, a keyword or symbol is often needed to delimit the beginning of the body from the element (i.e. if, elsif, for loop, while loop) to which it pertains.

For the case of subprograms, packages, tasks and blocks this word is begin.

For example,

procedure Some_Procedure is
begin
    Do_Something;
    Do_Something_Else;
end Some_Procedure;

The begin keyword is always closed with the end keyword. The opposite is not true in Ada.

Keywords: body

This keyword is used to define the body (implementation) of the following units:

Keywords: case

This keyword is used in case statements and variant record definitions.

Keywords: constant

This keyword is used to declare constant objects and named numbers.

Keywords: declare

This keyword is used to mark beginning of the declarative part of a block.

Block_Name :
   declare
      A_Variable : The_Type;
   begin
      Use A_Variable
   end Block_Name;

The Block_Name is optional.

Keywords: delay

Delay statements

Relative delays

delay Wait_Time;

The Ravenscar profile forbids the use of the relative delay statement:

pragma Restrictions (No_Relative_Delay)

This language feature is only available from Ada 2005 on.

Absolute delays

delay until Next_Time;

Select statements

Delay alternative

Selective accept:

select
   when Cond =>
      accept_statement
      statements
or
  delay_alternative
end select;

Timed entry call

select
   entry_call_alternative
or
   delay_alternative
end select;

Asynchronous transfer of control

select
   delay until Abort_Time;
   statements
then abort
   abortable_part
end select;

Keywords: delta

Description

This keyword is used in the declaration of fixed point types. Delta represents the absolute error bound of a fixed point type; that is, delta gives a hint to the compiler how to choose the smallest incremental value of the type, called the Small of the type. This Small value is accessible via the attribute T'Small.

For Ordinary fixed point types, it is by default a power of two not greater than the delta; it is specifyable by an attribute clause to be any value not greater than the delta.

For decimal fixed point types, the Small value is equal to the delta, which of course must be a power of ten.

Example

type Fixed_Point is delta 0.01 digits 10;  -- A decimal fixed point type
My_Fixed_Point : Fixed_Point := 0.0;
...
My_Fixed_Point := 0.1;   -- Ok
My_Fixed_Point := 0.02;  -- Ok
My_Fixed_Point := 0.001; -- Oops - this value is too small.
                         -- It will be represented by zero.

Keywords: digits

This keyword is used in the declaration of floating point types and fixed point types.

Keywords: do

This keyword is used in accept statements.

Keywords: else

This keyword is used in:

Keywords: elsif

This keyword is used in 'if' statements.

Keywords: end

This keyword is used to mark the end of the following constructs:

Keywords: entry

This keyword is used to define a rendezvous in the context of tasking.

Keywords: exception

This keyword is used in exception declarations and exception handlers.

Keywords: exit

This keyword is used to exit the current or named loop, conditionally or unconditionally.

Keywords: for

This keyword is used in:

For loops
Representation clauses:
- attribute definition clause
- enumeration representation clause
- record representation clause
- at clause (obsolescent)
Quantified expressions
- Universal quantification
- Existential quantification

Nowadays representation clauses are formally called aspect clauses in the last versions of the Reference Manual due to some technicalities, although representation clauses is the name far more extended among Ada programmers. As a historical note, they were known as representation specifications (rep specs) in pre-Ada 83 proposals.^[1]

For loops

[loop name :] for var in [ reverse ] [type range] range loop
   ...
end loop [loop name];

Where range can be:

explicit range like "low .. high",
range of scalar or array type: type'Range (or type'Range(n) for multidimensional array types)
range of an array: array'Range (or array'Range(n) for multidimensional arrays)

Keyword in may also be followed by an iterable. This generalizes iteration by including types that have one of the interfaces defined in Ada.Iterator_Interfaces. This language feature has been introduced in Ada 2012.

Another generalized form of looping iteration uses the keyword of in place of in. The loop parameter is then referring to components of arrays or of iterable container types, directly. This language feature has been introduced in Ada 2012.

[loop name :] for var [: type] of [ reverse ] iterable loop
   ...
end loop [loop name];

Representation clauses

The keywords for, use and at are used for representation clauses.

A record representation clause specifies the Layout aspect of a record.

An enumeration representation clause specifies the Coding aspect of an enumeration type.

See Ada Programming/Representation_clauses.

Quantified expressions

This language feature has been introduced in Ada 2012.

Quantified expressions are Boolean expressions. They are either True or False, or propagate any exception raised during evaluation.

Universal quantification

Universal quantification expression:

(for all var in range => predicate)
(for all var of iterable => predicate)

Both forms evaluate to True when all of the values in range (of iterable) make the predicate yield True. Evaluation of predicate stops when either all values of loop parameter var have been exhausted, or when evaluation for some value yields False (short circuit).

Existential quantification

Existential quantification expression:

(for some var in range => predicate)
(for some var of iterable => predicate)

Both forms evaluate to True when some of the values in range (of iterable) makes the predicate yield True. Evaluation of predicate stops when either all values of loop parameter var have been exhausted, or when evaluation for some value yields True (short circuit).

References

↑ John Barnes (2003-03-25). High-Integrity Software — The SPARK Approach to Safety and Security. Addison-Wesley. ISBN 0-321-13616-0. Retrieved 2008-06-06. Representation clauses are now strictly known as aspect clauses — the name was changed in the 2000 Corrigendum for Ada 95 for subtle reasons that need not concern us; Ada historians might recall that they were known as representation specifications (rep specs) prior to the ANSI standardization in 1983. These various terminologies are all in use and the reader will encounter them in the literature. (pp.212–213)

Keywords: function

This keyword is used in:

the specification and body of functions, a kind of subprograms.
access to subprogram type declarations.

Keywords: generic

This keyword is used in generic units declarations.

Keywords: goto

This keyword "goto" is used in the goto statement.

For details see the chapter Ada Programming/Control - goto.

Keywords: if

This keyword is used in 'if' statements.

Keywords: in

This keyword is used in:

The in and in out mode of subprograms parameters.
membership tests
for loops
quantified expressions

Keywords: interface

Used to declare an interface. Interfaces are the most important innovation in Ada 2005. The basic semantic has been taken from the interface concept of the Java programming language. Interface inheritance is a reduced form of multiple inheritance.

Interface types

There are various forms of interfaces available:

Normal interface

The normal interface is declared as:

 type Printable is interface;

Limited interface

Can be used as interface to limited tagged type.

 type Printable is limited interface;

Synchronized interface

type Printable is synchronized interface;

All synchronized interfaces are also limited.

Task interface

Can be used as an interface to a task type.

type Printable is task interface;

All task interfaces are also synchronized.

Protected interface

Can be used as an interface to a protected type.

 type Printable is protected interface;

All protected interfaces are also synchronized.

Keywords: is

The keyword is separates the name of an entity from its definition.

In type declarations

type Day_Of_Month is new range 1 .. 31;

See Ada Programming/Types and Ada Programming/Subtypes.

In subtype declarations

subtype Day_Of_February is Day_Of_Month range 1 .. 29;

See Ada Programming/Subtypes.

In package declarations

package My_Package is
   ... -- declarations
end My_Package;

See Ada Programming/Packages.

In procedure and function declaration

procedure My_Procedure is
   ... -- declarations    
begin
   ... -- sentences    
end My_Procedure;

See Ada Programming/Subprograms.

In generic instantiations

package Day_Of_Month_IO is 
      new Ada.Text_IO.Integer_IO (Num => Day_Of_Month);

See Ada Programming/Generics.

Keywords: limited

This keyword is used to define limited types.

Keywords: loop

This keyword is used in loop statements.

Keywords: mod

This keyword is used in the mod operator and in the declaration of modular types.

Keywords: new

Declaration

In type derivation

type Day_Of_Month is new Integer range 1 .. 31;

See Declaring new Types.

In type extension

type Derived_Tagged_Type is new Parent_Tagged_Type with
   record
      New_Data : Data;
   end record;

See Ada Programming/Object Orientation.

In instantiation of generics

package Day_Of_Month_IO is
      new Ada.Text_IO.Integer_IO (Day_Of_Month);

See Generics.

Allocator

type Day_Of_Month_Access is access Day_Of_Month;

X : Day_Of_Month_Access := new Day_Of_Month'(5);

See Creating object in a storage pool.

Keywords: not

This keyword is used in:

Keywords: null

This keyword is used for:

Keywords: of

This keyword is used in array types declarations and for loops.

Keywords: or

Logical operator

Boolean operator

X : Boolean := A < 10 or A > 20;

Boolean shortcut operator

In the below example the function G is only called when F(X) returns the value False.

if F(X) or else G(Y) then

    Walk_The_Dog;
 
end if;

This shortcut operator is sometimes used to speed up the evaluation of boolean expressions, but the Ada Style Guide recommends to compare the performance of both forms before switching one to the other. In general, it is good idea to use or else in sake of performance only when the second expression involves a function call.

The or else form is also used when the second expression is known to raise an exception unless the first expression is False.

Unlike C/C , Ada short-cut operators are not the standard way to evaluate boolean expressions. This is because Ada is designed to do by default what is generally safer, but lets the programmer request a different behaviour.

Boolean operator on arrays

The or operator is applied to each pair of boolean elements from the left and right arrays. The result has the same bounds as the left operand.

type Day_Of_Month is range 1 .. 31;            
type Month_Array is array (Day_Of_Month) of Boolean;

X : Month_Array := Function_1;
Y : Month_Array := Function_2;
Z : Month_Array := X or Y;

Bitwise operator

The operator or could be used with modular types to perform bitwise operations.

Select statement

alternative

See Ada Programming/Tasking#Selective waiting.

delay

See Ada Programming/Tasking#Timeout.

Keywords: others

Summary

The keyword others is used to define the remaining options in a list of options:

Keywords: out

This keyword is used in the out and in out mode of subprograms parameters.

Keywords: overriding

The keyword overriding can be used to explicitly declare a procedure or function as an overriding subprogram. There are two forms available:

overriding
procedure Overriding_Procedure (This: in Class_Type);

not overriding
procedure Not_Overriding_Procedure (This: in Class_Type);

The first declares the procedure as overriding the second does not.

Keywords: package

This keyword is used in regular packages (specification and body), in generic packages (specification and body), and in generic formal package parameters.

Keywords: pragma

This keyword is used in pragma statements.

Keywords: private

This keyword is used to declare:

Keywords: procedure

This keyword is used in:

the specification and body of procedures, a kind of subprograms.
access to subprogram type declarations.
Procedures as parameters in generic units.

Keywords: protected

This keyword is used in the definition of protected types.

Keywords: raise

This keyword is used for raising a named exception or reraising the current exception in an exception handler.

Keywords: range

Description

The keyword range is used in the following type definitions.

Defining the first and last element in an integer range.
Defining the first and last element in a Modulus subtype.
Defining the first and last element in an enumeration subtype.
Defining the minimum range of a floating point type.
Defining the minimum range of a fixed point type.
Defining the range of an array type.

It is also used within the following statements:

Specify the range of a for loop.

Keywords: record

This keyword is used in record types declarations.

Keywords: rem

Operator rem

The rem keyword is used as the remainder operator, that is, the remainder of the signed integer division. The following formula applies:

A = (A / B) * B   (A rem B)

Keywords: renames

This keyword is used in renaming declarations.

Keywords: requeue

This keyword is used for requeue statements.

Keywords: return

This keyword is used in:

Functions specifications for declaring the returned type.
In function bodies for returning a value to the caller.
In procedure bodies for returning the control to the caller.

Keywords: reverse

This keyword is used in for loops to specify that the loop is performed in reverse order:

  for I in reverse 1 .. 10 loop
     Ada.Integer_Text_IO.Put (I);
     Ada.Text_IO.New_Line;
  end loop;

Outputs:

Keywords: select

This keyword is used in selective waiting in tasks.

Keywords: separate

This keyword is used to declare subunits.

Keywords: subtype

Summary

The keyword subtype is used to declare and name a new subtype. For more information on types and subtypes read Ada Programming/Subtypes.

Keywords: synchronized

This language feature is only available from Ada 2005 on.

The synchronized keyword is used to declare that the interface has to be implemented by task types or protected types. The syntax is:

type Printable is synchronized interface;

Keywords: tagged

This keyword is used in object-oriented type declarations (tagged types).

Keywords: task

The keyword task is used to define either a task or task type. See Ada Programming/Tasking for more information on the Ada tasking system.

Keywords: terminate

This keyword is used in task termination.

Keywords: then

This keyword is used in:

Keywords: type

The keyword type is used to declare a new type and name the first subtype. For more information on types and subtypes read Ada Programming/Type System.

Keywords: until

Delay until statement

The keyword until is used only in delay until statements.

Keywords: use

Use clause

There are two versions of use clauses, a use_package_clause and a use_type_clause.

At library level

This use_package_clause makes the content of a package directly visible. If applied on the library level, its scope is the complete library unit.

A use clause never hides anything that is already directly visible without it. All use clauses in effect in a certain scope act on the same level: Two homographs in different packages must still be named as selected components.

with Ada.Text_IO;   use Ada.Text_IO;

procedure Hello is
begin
   Put_Line("Hello, world!");
   New_Line;
   Put_Line("I am an Ada program with package use.");
end Hello;

If readability is your main concern then you should avoid this kind of use clause. Either make it more local or use a use_type_clause.

At declaration level

The effect is the same as above, but the scope is the directly enclosing declaration region.

File: hello_world_3.adb (view, plain text, download page, browse all)

with Ada.Text_IO;

procedure Hello is
   use Ada.Text_IO;
begin
   Put_Line("Hello, world!");
   New_Line;
   Put_Line("I am an Ada program with package use.");
end Hello;

For types

Use type clauses come in two versions.

use type Type_Name;

makes the operators of the type directly visible.

use all type Type_Name;

makes the primitive operations of the type directly visible.

Representation clauses

The keywords for, use and at are used for representation clauses.

A record representation clause specifies the Layout aspect of a record.

An enumeration representation clause specifies the Coding aspect of an enumeration type.

See Ada Programming/Representation_clauses.

Keywords: when

This keyword is used in:

case statements,
variant record definitions,
exception handlers
loops exit conditions.

Keywords: while

This keyword is used in the while loops.

Keywords: with

This keyword is used in:

With clauses
Extension declarations in OOP
Subprogram and package parameters in generics
Aspects (Ada 2012)

Keywords: xor

Logical operator

Boolean operator

X : Boolean := A = 10 xor B = 10;

Boolean operator on arrays

The xor operation is applied to each boolean inside the array.

type Day_Of_Month is range 1 .. 31;            
type Month_Array is array (Day_Of_Month) of Boolean;

X : Month_Array := Function_1;
Y : Month_Array := Function_2;
Z : Month_Array := X xor Y;

Bitwise operator

The operator xor could be used with modular types and also with boolean arrays to perform bitwise operations.

GNU Free Documentation License

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

0. PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional and useful document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

1. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.

A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none.

The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words.

A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not "Transparent" is called "Opaque".

Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only.

The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text.

The "publisher" means any person or entity that distributes copies of the Document to the public.

A section "Entitled XYZ" means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as "Acknowledgements", "Dedications", "Endorsements", or "History".) To "Preserve the Title" of such a section when you modify the Document means that it remains a section "Entitled XYZ" according to this definition.

The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License.

2. VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

You may also lend copies, under the same conditions stated above, and you may publicly display copies.

3. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

4. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.
State on the Title page the name of the publisher of the Modified Version, as the publisher.
Preserve all the copyright notices of the Document.
Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice.
Include an unaltered copy of this License.
Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.
Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.
For any section Entitled "Acknowledgements" or "Dedications", Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.
Delete any section Entitled "Endorsements". Such a section may not be included in the Modified version.
Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title with any Invariant Section.
Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.

You may add a section Entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties—for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

5. COMBINING DOCUMENTS

You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections Entitled "History" in the various original documents, forming one section Entitled "History"; likewise combine any sections Entitled "Acknowledgements", and any sections Entitled "Dedications". You must delete all sections Entitled "Endorsements".

6. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

7. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an "aggregate" if the copyright resulting from the compilation is not used to limit the legal rights of the compilation's users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document's Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.

8. TRANSLATION

Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.

If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.

9. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.

However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.

Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.

Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it.

10. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Document.

11. RELICENSING

"Massive Multiauthor Collaboration Site" (or "MMC Site") means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A "Massive Multiauthor Collaboration" (or "MMC") contained in the site means any set of copyrightable works thus published on the MMC site.

"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization.

"Incorporate" means to publish or republish a Document, in whole or in part, as part of another Document.

An MMC is "eligible for relicensing" if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008.

The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing.

How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

Copyright (c) YEAR YOUR NAME.

Permission is granted to copy, distribute and/or modify this document

under the terms of the GNU Free Documentation License, Version 1.3

or any later version published by the Free Software Foundation;

with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.

A copy of the license is included in the section entitled "GNU

Free Documentation License".

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this:

with the Invariant Sections being LIST THEIR TITLES, with the

Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.

If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

[1] John Barnes (2003-03-25). High-Integrity Software — The SPARK Approach to Safety and Security. Addison-Wesley. ISBN 0-321-13616-0. Retrieved 2008-06-06. Representation clauses are now strictly known as aspect clauses — the name was changed in the 2000 Corrigendum for Ada 95 for subtle reasons that need not concern us; Ada historians might recall that they were known as representation specifications (rep specs) prior to the ANSI standardization in 1983. These various terminologies are all in use and the reader will encounter them in the literature. (pp.212–213)

[1]

Keywords

Language summary keywords

List of keywords

See also

Wikibook

Ada Reference Manual

Ada 83

Ada 95

Ada 2005

Ada 2012

Ada 2022

Ada Quality and Style Guide

Keywords: abort

abort

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: abs

See also

Wikibook

Ada 95 Reference Manual

Ada 2005 Reference Manual

Ada Quality and Style Guide

Keywords: abstract

Summary

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: accept

Summary

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: access

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: aliased

Description

For variables

For type declarations

For the elements of an array

For the elements of a record

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: all

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: and

Logical operator

Boolean operator

Boolean shortcut operator

Boolean operator on arrays

Bitwise operator

Adding interfaces to tagged types

See also

Wikibook

Ada 95 Reference Manual

Ada 2005 Reference Manual

Ada Quality and Style Guide

Keywords: array

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: at

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide

Keywords: begin

See also