[Haskell-cafe] typing hmatrix expressions

[Carter Schonwald]

hello alberto,
i've had some funny issues with using the cmap function, and i'd like
understand what i'm doing wrong
namely it wont correctly instantiate for vectors or matrices and I don't
understand why.

basically my question  is:

what is the correct type for the hmatrix expression

mapMat f  =liftMatrix $! cmap f


I'd like to just give it a type like
Storable a => (a->a)-> Matrix a -> Matrix a

but i get an error message like
Electrical.lhs:89:29:
    No instance for (Container Vector e0)
      arising from a use of `cmap'
    Possible fix: add an instance declaration for (Container Vector e0)
    In the second argument of `($!)', namely `cmap f'
    In the expression: liftMatrix $! cmap f
    In an equation for `mapMat': mapMat f = liftMatrix $! cmap f

which i feel shouldn't be happening.

is the type of cmap in some way too polymorphic, or am I just not turning on
the right ghc type extensions for this to work,
or is this something that would have been well typed prior to ghc 7? Or am i
just not correctly understanding this type error and i'm making a simple
mistake?

thanks!
-Carter
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