On 8/02/2011, at 10:00 AM, Andrew Coppin wrote: > I clearly have my languages mixed up. > > The language I'm thinking of required all variables (even top-level ones) to > be declared with "let" - unless the definition is recursive, in which case > you have to say "letrec" (i.e., the compiler it too stupid to deduce this > automatically). Apparently that isn't Clean...
That sounds like an ML-family language, possibly OCAML. However, this is *not* a question of stupidity. It's a question of scope rules. Example 1: let f x = 1;; let f x = if x = 0 then 0 else f x;; f 3;; This answers 1. Example 2: let f x = 1;; let rec f x = if x = 0 then 0 else f x;; f 3;; This goes into an infinite loop. If you don't like redeclaration, which is rather useful in an interactive top level, try nested: let f x = 1;; let g y = let f x = if x = 0 then 0 else f x in f (f y);; vs let f x = 1;; let g y = let rec f x = if x = 0 then 0 else f x in f (f y);; The distinction between let and letrec predates OCAML. Scheme does it too. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
