On 10/23/07, Jules Bean
I believe it is to do with the requirement that expressions have a unique principle type. Certainly in principle the algorithm you outline is possible, but I don't know what else you would lose.
I'm not familiar with the term "principal type". I shall have to study it.
And I would like to say that whether or not I need it is not the issue, as I currently do not in fact need it. This is a study of the Haskell language not my possible practical applications of it.
Whether one needs it, or does not need it, is indeed an issue: any change to the type inference algorithm has a cost. That cost has to be judged against the value of it. If an extension is seldom needed, then its value is low, so the cost is unlikely to be considered worth it. If an extension is frequently need and the cost is low, then that argues for it..
Ah... harsh realities of engineering. Well I hope this is judged to be important enough to be included in a future revision of Haskell. Thanks, TJ