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Whiley is a programming language created in 2009 by David J. Pearce.

#514on PLDB 15Years Old 2Repos
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Whiley is an experimental programming language that combines features from the functional and imperative paradigms, and supports formal specification through function preconditions, postconditions and loop invariants. The language uses flow-sensitive typing also known as "flow typing." The Whiley project began in 2009 in response to the "Verifying Compiler Grand Challenge" put forward by Tony Hoare in 2003. The first public release of Whiley was in June, 2010.Primarily developed by David Pearce, Whiley is an open source project with contributions from a small community. Read more on Wikipedia...

Example from the web:
// Define the type of natural numbers type nat is (int x) where x >= 0 public function indexOf(int[] items, int item) -> (int|null index) // If int returned, element at this position matches item ensures index is int ==> items[index] == item // If int returned, element at this position is first match ensures index is int ==> no { i in 0 .. index | items[i] == item } // If null returned, no element in items matches item ensures index is null ==> no { i in 0 .. |items| | items[i] == item }: // nat i = 0 // while i < |items| // No element seen so far matches item where no { j in 0 .. i | items[j] == item }: // if items[i] == item: return i i = i + 1 // return null
Example from hello-world:
import std::ascii import std::io method main(ascii::string[] args): io::println("Hello World")

Language features

Feature Supported Token Example
MultiLine Comments โœ“
Binary Literals โœ“
// [01]+b
Integers โœ“
// [0-9]+
Floats โœ“
// [0-9]+\.[0-9]+
Hexadecimals โœ“
// 0x[0-9a-fA-F]+
Strings โœ“ "
"Hello world"
Print() Debugging โœ“ io::println
Comments โœ“
// A comment
Line Comments โœ“ //
// A comment
Semantic Indentation X

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