The Upconvert framework allows convenient, lossless conversions between different types in Swift 4. Conversion is performed using the upconversion operator, ^:

let small: Int8 = 1
let large: Int = 100_000
print(large   ^small)       // => 100002

Upconversion is only allowed when the destination type is large enough to contain all possible values of the source type. Otherwise, your code will not compile.

let small: Int8 = 1
let large: Int = 100_000

large   ^small      // OK
^large   small      // Error

Upconvert ships with the following conversions built in:

• Int8 → Int16 → Int32 → Int → Int64
• UInt8 → UInt16 → UInt32 → UInt → UInt64
• Float → CGFloat → Double → Float80
• Substring → String
• UnicodeScalar → Character → String
• KeyPath → getter function

The KeyPath upconversion allows you to use key paths with functions like map and filter:

let names = people.map(^\.name)

You can add your own upconversions by conforming types to the Upconvertible protocol.

Just clone it and put the project into Xcode. Pull requests to support package managers are welcome.

• Downconversions—potentially lossy conversions—are not supported.

• Each type can only upconvert to one other type (plus the type it upconverts to, recursively). This is why you can't upconvert a UInt32 to an Int64.

• The ^ operator will only recurse so far (five levels currently).

• The Int and UInt conversion sequences don't support the new DoubleWidth type due to limitations in its current implementation.

• This design is bleeding-edge; don't consider the interface to be stable yet.

Brent Royal-Gordon, Architechies.

Copyright © 2017 Architechies. Distributed under the MIT License.