[Haskell-cafe] functional dependencies question

Ketil Malde ketil at malde.org
Thu Jul 1 08:14:05 EDT 2010

Patrick Browne <patrick.browne at dit.ie> writes:

> Why do some cases such as 1) fail to run even if they are the only
> instantiation.

I think this is because literal numbers are polymorphic, i.e. a '1' in
your source code is shorthand for 'fromIntegral 1', which is a type of
Num a => a.  Thus, 'spatialLocation 1' doesn't tell the compiler enough
to know that you don't want the Float instance, for instance.

Try 'spatialLocation (1::Int)'?

Similar for floating point literals, they are of type Fractional a => a.

If I haven't seen further, it is by standing in the footprints of giants

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