On 28/11/2006, at 11:28 AM, Ian Lynagh wrote:
On Mon, Nov 20, 2006 at 12:05:46PM +0000, Malcolm Wallace wrote:
Prompted by recent discussion on the Hat mailing list about the
problems
of type-defaulting, I have added two new proposals for this issue
to the
Haskell-prime wiki at:
http://hackage.haskell.org/trac/haskell-prime/wiki/Defaulting
I don't see a proposal to remove defaulting defaulting altogether on
that page - has that been discussed already?
Am I the only one who puts an explicit type signature in whenever my
compiler warns me that it is having to do some defaulting? And
probably
99% of those would be unnecessary if (^)'s second argument was an Int,
with a genericPower (or whatever) function providing the current type
signature (analogous to, for example, (!!) and genericIndex).
Defaulting is one wart I would be glad to be rid of.
I would also be happy if it was removed.
My main reasons are:
1) It makes teaching Haskell more difficult, because it is a special
case
mechanism. I would prefer consistency here.
2) It makes source-to-source program transformations more difficult, as
found in Hat etc.
3) I have found it easy to avoid with the addition of type annotations.
I don't write a lot of numeric code, so the benefits I personally get
from defaulting have
so far been minimal, and that has coloured my view. Others may find
it more
useful.
Cheers,
Bernie.
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