[Haskell-beginners] Could not deduce (Matrix m (Maybe a)) from
the context (Matrix m a)
Lyndon Maydwell
maydwell at gmail.com
Fri Jan 29 06:11:43 EST 2010
Ah, yes. That might be just what I'm after!
> However, having a look, none of the methods in the class look like they
> depend on the actual type a, so it might be better to have
>
> class Matrix m where
> fromRows :: [[a]] -> m a
> toList :: m a -> [a]
> rows :: m a -> Integer
> columns :: m a -> Integer
> row :: m a -> Integer -> [a]
> column :: m a -> Integer -> [a]
> at :: m a -> Integer -> Integer -> a
> (!!!) :: m a -> Integer -> Integer -> a
> vicinityRows :: m a -> Integer -> Integer -> [[Maybe a]]
> vicinityMatrix :: m a -> Integer -> Integer -> m (Maybe a)
> -- No constraint needed!!
> neighbours :: m a -> Integer -> Integer -> [a]
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