Mark H Weaver <m...@netris.org> writes: > The 'letrec' form above is indeed invalid. As the R5RS states: > > One restriction on 'letrec' is very important: it must be possible > to evaluate each <init> without assigning or referring to the value > of any <variable>. If this restriction is violated, then it is an > error. The restriction is necessary because Scheme passes > arguments by value rather than by name. In the most common uses of > 'letrec', all the <init>s are lambda expressions and the > restriction is satisfied automatically.
Yeah, I'd read that originally, but not paid quite close enough attention (obviously). Switching to a wrapper lambda worked just fine. > This particular example happens to work when compiled by recent versions > of Guile, but that's suboptimal. Ideally, we should report an error in > this case. Indeed, not strictly necessary, but would have been nice, so I'd have realized more quicly that I was doing it wrong. Thanks again for the help. -- Rob Browning rlb @defaultvalue.org and @debian.org GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A GPG as of 2002-11-03 14DD 432F AE39 534D B592 F9A0 25C8 D377 8C7E 73A4
