The Koka Programming Language

Published on 02 May 2020 (Updated: 18 May 2022)

The Koka Programming Language

Welcome to the Koka page! Here, you’ll find a description of the language as well as a list of sample programs in that language.


Koka is a function-oriented programming language created by Microsoft researcher [Daan Leijen][1]. Leijan created Koka to separate pure values from side-effecting computations. According to [Wikipedia][2], a function or expression is said to have a side effect if it modifies some state outside of its local environment.

In addition, Koka has many features that help programmers easily change their data types and code organization correctly while having a small language core with a familiar JavaScript-like syntax.

Fun Fact: the word ‘Koka’ (or 効果) means “effect” or “effective” in Japanese.