Hi guys, On #guile, euiuer (CCed) reported this, though he was to shy to report this himself. In guile 1.8.7
<euiuer> (define (foo) (+ 1 1)) <euiuer> (define (+ a b) (- a b)) <euiuer> (display (foo)) <euiuer> (display (+ 1 1)) <euiuer> it evails like 0 and 0. <euiuer> but.. <euiuer> (define (foo) (+ 1 1)) <euiuer> (display (foo)) <euiuer> (define (+ a b) (- a b)) <euiuer> (display (foo)) <euiuer> (display (+ 1 1)) <euiuer> it evails like 2 2 0 <euiuer> it is kind of odd. He confirms he gets these when he runs these from a script. I get the same on my 1.8.8 install, both at the repl and from a script. Since it evaluates correct if we run (bar) _after_ redefining + I think it's a safe bet to assume that 1.8 cached the reference to +, but not having been around for 1.8, this is a conjecture only. Now, 1.8 is the old series, how about 2? Running a recent master (9b977c836bf147d386944c401113aba32776fa68)[0]. >From the repl: scheme@(guile−user)> (define (foo) (+ 1 1)) scheme@(guile−user)> (define (+ a b) (- a b)) scheme@(guile−user)> (foo) $2 = 2 scheme@(guile−user)> (+ 1 1) $3 = 0 and scheme@(guile−user)> (define (foo) (+ 1 1)) scheme@(guile−user)> (foo) $2 = 2 scheme@(guile−user)> (define (+ a b) (- a b)) scheme@(guile−user)> (foo) $3 = 2 scheme@(guile−user)> (+ 1 1) $4 = 0 >From a script $ guile -q -s /tmp/file1.scm 22 $ guile -q -s /tmp/file2.scm 222 This behaviour can be "blamed" on guile 2's more aggressive optimisation. Indeed, scheme@(guile−user)> ,disassemble foo Disassembly of #<procedure foo ()>: 0 (assert−nargs−ee/locals 0) ;; 0 args, 0 locals 2 (make−int8 2) ;; 2 at (unknown file):5:14 4 (return) is pretty much what we want usually. And I'm inclined to say NOTABUG for the repl when optimisation is turned on. However, in a script, this is a bug IMO, since we shouldn't really be optimising + if our top-level binding for + is not the builtin one, and we can certainly detect a redefinition of + within a file. Just to be sure, I tried turning off cse and peal, but ran into a different optimisation scheme@(guile−user)> ,option compile-options (#:partial-eval? #f #:cse? #f) scheme@(guile−user)> ,option compile-options (#:partial−eval? #f #:cse? #f) scheme@(guile−user)> (foo) $2 = 2 scheme@(guile−user)> (+ ) $3 = 0 scheme@(guile−user)> (define (+ a b) (- a b)) scheme@(guile−user)> (foo) $4 = 2 scheme@(guile−user)> (+ 1 1) $5 = 0 Have you guessed what it was? scheme@(guile−user)> ,disassemble foo Disassembly of #<procedure foo ()>: 0 (assert−nargs−ee/locals 0) ;; 0 args, 0 locals 2 (make−int8:1) ;; 1 3 (add1) at (unknown file):44:14 4 (return) So, you can't win on this one :) [0] I have not got a stable-2.0 install at the moment to compare, but I suspect it will be similar. -- Ian Price -- shift-reset.com "Programming is like pinball. The reward for doing it well is the opportunity to do it again" - from "The Wizardy Compiled"
