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Io is a programming language created in 2002 by Steve Dekorte.

#438on PLDB 22Years Old 2kRepos

Try now: Riju · TIO

Io is a pure object-oriented programming language inspired by Smalltalk, Self, Lua, Lisp, Act1, and NewtonScript. Io has a prototype-based object model similar to the ones in Self and NewtonScript, eliminating the distinction between instance and class. Like Smalltalk, everything is an object and it uses dynamic typing. Read more on Wikipedia...

Example from Riju:
"Hello, world!" println
Example from hello-world:
"Hello World\n" print
Example from Wikipedia:
factorial := method(n, if(n == 0, return 1) res := 1 Range 1 to(n) foreach(i, res = res * i) )

Language features

Feature Supported Token Example
MultiLine Comments
// \d+
// (\d+\.?\d*|\d*\.\d+)([eE][+-]?[0-9]+)?
Assignment :=
Print() Debugging print
Line Comments //
// A comment
Operator Overloading
Semantic Indentation X

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- Build the next great programming language · About · Acknowledgements · Published by Breck's Lab