On Fri, Dec 29, 2006 at 02:06:32PM +0000, Paul Moore wrote: > Speaking as a relative newbie to Haskell, the thing that tripped me up > was the fact that you can't have nested lists like the Lisp '(1 (2 (3 > 4) 5)) example in Haskell, because its type is not well-defined.
More precisely: You can't ununiformly nest standard [] lists. By ununiformly I mean: with leaves on different depths. You can do it with another list (or rather tree) implementation. You can nest [] lists uniformly, ie. [[1], [2,3,4]] is a nested list. > OTOH, it's not entirely clear to me if the issue would come up in > "real" code. It depends on what you mean by "issue". If syntactical overhead is an issue, then it comes up. For me it's a small issue, if at all. > Slinging about arbitrarily nested lists feels quite natural in Lisp, > but isn't really idiomatic Haskell. Nested lists are trees and using tree-like structures in Haskell is very idiomatic. Perhaps you would want some syntactic sugar for trees. If [] lists didn't have sugar in Haskell, they would be as "cumbersome" to use as trees. Best regards Tomasz _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
