[Haskell-beginners] question about list processing

[Martin Vlk]

How about:

computeHead f = take 1 . fmap f

Martin

Dennis Raddle:
> What would be an elegant way of writing this
> 
> computeHead :: (a -> [b]) -> [a] -> [b]
> 
> Where when [a] is null, it returns a null list, but when [a] contains one
> or more elements, it applies the given function to the head of a and
> returns that? Is there some existing typeclass operator that facilitates
> this?
> 
> You can write
> 
> computeHead _ [] = []
> computeHead f (x:_) = f x
> 
> But that first line seems suspicious to me... it makes me think about how
> in the list Monad, an empty list falls through. But I can't quite make it
> work.
> 
> 
> 
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