Hi Matt, Matt Wette <matt.we...@gmail.com> writes:
> I'm trying to generate CPS to feed to the compiler tower. > The following program is supposed to evaluate, expressed in Scheme, `(+ 1 2)'. > That is, essentially, > scheme@(guile-user)> (apply + '(1 2)) > $1 = 3 > I get the error message following. Any clues what is going on? > > (0 . #<cps (kfun () 0 1 9)>) > (1 . #<cps (ktail)>) > (2 . #<cps (kargs (rval) (1) (continue 1 (values 1)))>) > (3 . #<cps (kargs (arg) (4) (continue 2 (call 2 3 4)))>) > (4 . #<cps (kargs (arg) (3) (continue 3 (const 2)))>) > (5 . #<cps (kargs (arg) (2) (continue 4 (const 1)))>) > (6 . #<cps (kargs (t) (6) (continue 5 (primcall resolve 5 6)))>) The problem here is that 'resolve' returns a variable object, but 'call' expects a procedure. So, you need another continuation between continuations 6 and 5 above, which does (primcall box-ref <>) to extract the procedure from the variable object. Also, I believe the (values 1) in continuation 2 above is incorrect. It expects its argument to be a list, whereas in this case it would be a number. It's not needed here. > And if I fire up Guile and turn off optimization, I get this, where I don't > even see the + resolved. > scheme@(guile-user)> (define v (compile '(+ 1 2) #:from 'scheme #:to 'cps)) > scheme@(guile-user)> (disp-cps v) > (0 . #<cps (kfun () 0 1 4)>) > (1 . #<cps (ktail)>) > (2 . #<cps (kargs (val) (1) (continue 1 (values 1)))>) > (3 . #<cps (kargs () () (continue 2 (const 3)))>) > (4 . #<cps (kclause (() () #f () #f) 3)>) '+' is converted into a primitive operation in an early phase of compilation. For these purposes, it's probably better to choose a procedure that won't be recognized specially by the compiler. --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> ,use (system base compile) scheme@(guile-user)> (define intmap->alist (@@ (language cps intmap) intmap->alist)) scheme@(guile-user)> (define v (compile '(floor/ 3 7) #:from 'scheme #:to 'cps)) scheme@(guile-user)> ,pp (intmap->alist v) $2 = ((0 . #<cps (kfun () 0 1 9)>) (1 . #<cps (ktail)>) (2 . #<cps (kargs (arg) (3) (continue 1 (call 1 2 3)))>) (3 . #<cps (kargs (arg) (2) (continue 2 (const 7)))>) (4 . #<cps (kargs (arg) (1) (continue 3 (const 3)))>) (5 . #<cps (kargs (box) (4) (continue 4 (primcall box-ref 4)))>) (6 . #<cps (kargs (bound?) (6) (continue 5 (primcall resolve 5 6)))>) (7 . #<cps (kargs (name) (5) (continue 6 (const #t)))>) (8 . #<cps (kargs () () (continue 7 (const floor/)))>) (9 . #<cps (kclause (() () #f () #f) 8)>)) scheme@(guile-user)> --8<---------------cut here---------------end--------------->8--- Admittedly, I manually cleaned up the output of ,pp here. Anyway, see the 'box-ref' expression above, which was missing from yours, and also note that in the CPS above, 'call' returns directly to the $ktail, without an intervening 'values'. Hope this helps, Mark