Y combinator: Difference between revisions

<syntaxhighlight lang="forth">

\ Begin of aproach. Depends on 'latestxt' word of GForth implementation.

: self-parameter ( xt -- xt' )

>r :noname latestxt postpone literal r> compile, postpone ;

;

: Y ( xt -- xt' )

dup self-parameter 2>r

:noname 2r> postpone literal compile, postpone ;

;

</syntaxhighlight>Usage:<syntaxhighlight lang="forth">

\ Fibonnacci test

10 :noname ( u xt -- u' ) over 2 < if drop exit then >r 1- dup r@ execute swap 1- r> execute + ; Y execute . 55 ok

\ Factorial test

10 :noname ( u xt -- u' ) over 2 < if 2drop 1 exit then over 1- swap execute * ; Y execute . 3628800 ok

\ End of aproach.

</syntaxhighlight><syntaxhighlight lang="forth">\ Address of an xt.