On 2009 Mar 20, at 20:14, Brandon S. Allbery KF8NH wrote:
On 2009 Mar 20, at 20:07, Zachary Turner wrote:
2009/3/20 Brandon S. Allbery KF8NH
<allbery@ece.cmu.edu> ...but there is (%) :: (Integral a) => a -> a -> Ratio a
Prelude Data.Ratio> let y = truncate (x%3)
Prelude Data.Ratio> :t y
y :: Integer
Why does y now have the type Integer instead of Int?
Because of the monomorphism restriction and defaulting. Actually use it somewhere and it will take the appropriate (Integral) type.
uh, clarification: because y has no arguments, the monomorphism restriction comes into play; if you define y as above in a program it will also end up defaulting to Integer. The expression "truncate (x%3)", on the other hand, is of type "Integral a => a" (as long as it's not placed into a context that triggers monomorphism).
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electrical and computer engineering, carnegie mellon university KF8NH