rosetta/ackermann_function.bruijn

:import std/Combinator .
:import std/Number/Unary U
:import std/Math .

# unary ackermann
ackermann-unary [0 [[U.inc 0 1 (+1u)]] U.inc]

:test (ackermann-unary (+0u) (+0u)) ((+1u))
:test (ackermann-unary (+3u) (+4u)) ((+125u))

# ternary ackermann (lower space complexity)
ackermann-ternary y [[[=?1 ++0 (=?0 (2 --1 (+1)) (2 --1 (2 1 --0)))]]]

:test ((ackermann-ternary (+0) (+0)) =? (+1)) ([[1]])
:test ((ackermann-ternary (+3) (+4)) =? (+125)) ([[1]])

main [[0]]