Note that at least for the dropWhile example, there is a specialized function, dropWhileEnd, which is most likely more efficient than reversing the list twice.

On Aug 17, 2013 3:35 PM, "Tom Ellis" <tom-lists-haskell-cafe-2013@jaguarpaw.co.uk> wrote:
On Sat, Aug 17, 2013 at 11:11:07AM +0200, Christopher Done wrote:
> Anyone ever needed this? Me and John Wiegley were discussing a decent
> name for it, John suggested inv as in involution. E.g.
>
> inv reverse (take 10)
> inv reverse (dropWhile isDigit)
> trim = inv reverse (dropWhile isSpace) . dropWhile isSpace

This sounds like a job for a lens, or similar.

Tom


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