Dave Hinton wrote:
Arithmetic operators in haskell appear to require their operands to have the same type. How can I do arithmetic between operands of different types?
Alternatively, how do I coerce a value from being an Int to being a Double?
fromIntegral can do this coercion. It is more general: the input can be Int or Integer; the output can be any numeric type. There is also realToFrac: the input can be Int, Integer, Float, Double, or Ratio a (eg Rational); the output can be Float, Double, Ratio a (eg Rational), or Complex a. (Someone please compare their costs wherever comparable. I have a feeling that most compilers make fromIntegral faster than realToFrac for, say, Int -> Double.) When you have time, you may like to find out more about "type classes". In short, it is the way Haskell provides operator overloading. Numeric types use this scheme to achieve the above generality. If you know type classes, you have access to the full story.