explicit signatures and default for integer literals
robdockins at fastmail.fm
Tue May 31 09:16:39 EDT 2005
Dinko Tenev wrote:
> First we observe that, g = new . flip zip [0..], so, without the type
> specification, it has the general type (New [(a, b1)] b, Num b1, Enum
> b1) => [a] -> b, as reported by GHC.
> Then we infer from
> (1) g :: (New [(u, v)] w, Num v, Enum v) => [u] -> w
> (2) instance New [(a, b)] (Map a b)
> that in (New [(u, v)] w), w can only be (Map u v)
This step in the reasoning requires a functional dependency, which you
mentioned earlier you were unwilling to supply. Without functional
dependencies w can, in fact, be something other than (Map u v).
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