( ($x x) $force (force cswap $_ force) $if ($f $t $c $fn ^f ^t ^c fn) $endif ; Y-Combinator ($f ($x (^x x) f) ($x (^x x) f) force ) $Y ; rec: syntax sugar for applying the Y-Combinator ($g (^g Y)) $rec ; factorial ($self $n ^if (^n 0 eq 1) (^n 1 - self ^n *) endif ) rec $factorial 5 factorial print ) 

 ; compute [$comp $stack $env -> $stack] ($compute $eval ^if (dup is-nil) (rot $_ $_) ( ; false case: return $stack stack-pop ^if (dup 'quote eq) ($_ stack-pop rot swap stack-push swap ^eval compute) (swap $comp eval ^comp ^eval compute) endif ) endif ) rec $compute ; eval: [$expr $stack $env -> $stack $env] ($eval ^if (dup is-atom) ( over2 swap env-find dup $callable ^if (dup is-closure) (swap $stack cdr unpack-closure ^stack swap ^eval compute) (^if (dup is-clos) (force) (stack-push) endif) endif) (^if (dup is-list) (over2 swap make-closure stack-push) (stack-push) endif) endif ) rec $eval 

./build.sh 

./forsp examples/tutorial.fp ./forsp examples/demo.fp ./forsp examples/factorial.fp ./forsp examples/currying.fp ./forsp examples/church-numerals.fp ./forsp examples/higher-order-functions.fp ./forsp examples/church-numerals.fp ./forsp examples/low-level.fp ./forsp examples/fibonacci-imperative.fp ./forsp examples/fibonacci-functional.fp ./forsp examples/forsp.fp