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Paradigm(s) Functional
Designed by User:Hakerh400
Appeared in 2023
Computational class Turing complete
Major implementations Uniplemented
File extension(s) .txt

Functress is an esolang invented by User:Hakerh400 in 2023.


This programming language is a derivative of the SKI combinator calculus. There are three combinators K, S, R, and the following rewriting rules:

K a b           ---> a
S a b c         ---> a c (b c)
R K a b c d     ---> a
R S a b c d     ---> b
R R a b c d     ---> c
R (x y) a b c d ---> d x y

Reductions can be performed only at the beginning on the main expression. For example, R (K K K) does not reduce to R K, but R (K K K) a b c d does reduce to d (K K) K.