You can get rid of all recursive bindings by transforming them into a use of a fixpoint combinator. And then you can use a non-recursive definition of the fixpoint combinator, and never worry about recursive bindings again.
-- Lennart On Wed, Aug 27, 2008 at 8:59 PM, Andrew Coppin <[EMAIL PROTECTED]> wrote: > Hi guys. > > I'm writing a simple interpretter for a small extended-lambda-calculus sort > of language. And I'd just like to say... RECURSIVE LET-BINDS! GAAAAH!!! >_< > > No other part of the program has consumed nearly as much brain power as me > trying to figure out when it is and isn't safe to replace a variable with > its RHS. > > To illustrate: > > let x = f x; y = 5 in x y > > A simple-minded interpretter might try to replace every occurrance of "x" > with "f x". This yields > > let y = 5 in (f x) y > > ...and x is now a free variable. OOPS! > > Trying to tease out exactly under which conditions you can and cannot > perform the substitution is utterly maddening. Since this is a Haskell > mailing list and as such it is populated by vast numbers of people with PhDs > and so forth... does anybody happen to know the *correct* solution to this > conundrum? Before I become clinically insane...? o_O > > > > By the way... To all those people who work on projects like GHC and so on, > who have to get this stuff right "for real": you have my infinite respect! > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
