[Haskell-cafe] Mixed-type arithmetic, or type coercion
beakerchu at googlemail.com
Tue Mar 13 16:41:00 EDT 2007
Arithmetic operators in haskell appear to require their operands to
have the same type. How can I do arithmetic between operands of
Alternatively, how do I coerce a value from being an Int to being a Double?
I am new to haskell. I have read a few tutorials but they do not
mention this issue. I have read the haddock documentation for Prelude
and Numeric, but cannot find anything that helps here. (I saw a
couple of numeric conversion functions, but they won't turn an Int
into a Double.)
$ cat eg.hs
calc :: Int -> Double -> Double
calc count weight = count * weight
$ ghc eg.hs
Couldn't match `Int' against `Double'
Expected type: Int
Inferred type: Double
In the second argument of `(*)', namely `weight'
In the definition of `calc': calc count weight = count * weight
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