\ nsforth a small and slow implementation of a subset of Forth. : sq ( n -- n ) dup * ; : foo dup * 10 + ; 5 foo . 42 .s 3 zero? . see foo \ see foo definition ' foo . ' foo 32 .s swap .s create array1 4 allot \ 4 elements create array? 1 , 2 , : inc ( n1 -- n1 ) 1 + ; : dec ( n1 -- n1 ) 1 - ; 4 inc . 4 dec . \ Forth is a concatenative language, that is: : fn1 2 + ; : fn2 3 * ; : fn3 4 * ; 3 fn1 fn2 fn3 . forget fn1 forget fn2 forget fn3 \ 4 fn1 <- error : let create ; cst -4 3 - . \ if end 2 3 + 10 < if 3 sq . end let var1 2 , \ while end \ import file.fs