Brian Hulley wrote:
Fred Hosch wrote:
Is type inferencing in Haskell essentially the same as in SML?
The most significant difference certainly is that type inference has been beefed up with type classes in Haskell, which are quite a powerful mechanism refining Hindley/Milner inference. Besides that, Haskell allows some additional programs for which types can /not/ be inferred (e.g. the examples Brian was giving), while SML does not.
SML also has a complicated thing called the "value restriction" because it allows mutable references to be altered via side effects. Because Haskell has no side effects, there is no need for a value restriction.
Although there is no "need" for it, Haskell still has it, in minor variation. It is commonly known as "The Dreaded Monomorphism Restriction" ;). - Andreas -- Andreas Rossberg, rossberg@ps.uni-sb.de Let's get rid of those possible thingies! -- TB