[Haskell-cafe] Getting the x out
michael rice
nowgate at yahoo.com
Tue Apr 21 20:49:02 EDT 2009
How do I get the x out of Just x?
Michael
=============
safeDivision :: Float -> Float -> Maybe Float
safeDivision x y = if y == 0 then Nothing else Just (x/y)
*Main Data.List> safeDivision 10 5
Just 2.0
*Main Data.List> 3 + (safeDivision 10 5)
<interactive>:1:0:
No instance for (Num (Maybe Float))
arising from a use of `+' at <interactive>:1:0-22
Possible fix: add an instance declaration for (Num (Maybe Float))
In the expression: 3 + (safeDivision 10 5)
In the definition of `it': it = 3 + (safeDivision 10 5)
*Main Data.List>
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