2009/03/27 John Lato <[email protected]>: > From: Jules Bean <[email protected]> > > wren ng thornton wrote: > > > The type of head should not be [a] -> a + Error, it should > > > be (a:[a]) -> a. With the latter type the compiler can > > > ensure the precondition will be proved before calling > > > head, thus eliminating erroneous calls. > > > > Yes, but you know and I know that's not haskell. > > > > I'm talking about haskell. > > > > In haskell - a language which does not fully support > > dependent types - head is both necessary and useful. > > I could follow the rest of this, but I don't understand why > 'head' is necessary. Couldn't you always replace it with a > case statement, with undefined on [] if necessary?
How would that be any different from head? -- Jason Dusek _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
