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I don't remember if I answered this before, but... I don't see the relevance of there being no constructor to match on. That is the case for any tuple type. It seems that newtype T1 [a1 a2 ...] = C1 ... is the same as data T2 [a1 a2 ...] = C2 !... !... !... Except that pattern matching on C1 is like lazy pattern matching on C2. Since newtype is supposed to be about efficiency, I am trying to understand what makes this more efficient. I have not yet seen any explanation of this. On 22 Jan 2002, Martin [ISO-8859-1] Norbäck wrote: > tis 2002-01-22 klockan 15.52 skrev Feuer: > > Why is pattern matching on newtypes lazy? Does this add to efficiency > > somehow? If not, it seems to be just another rule to keep straight. > > That's the difference between newtype and data. Newtypes are unboxed, so > there is no constructor to match on. Pattern matching on newtypes is > only a type-checker thing, the constructor doesn't exist. > > Regards, > > Martin > > -- > [ http://www.dtek.chalmers.se/~d95mback/ ] [ PGP: 0x453504F1 ] [ UIN: > 4439498 ] > Opinions expressed above are mine, and not those of my future > employees. > SIGBORE: Signature boring error, core dumped > > _______________________________________________ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
