[Haskell-beginners] Calculations that might fail: with arrays

Christopher Howard christopher.howard at frigidcode.com
Thu Jun 9 02:09:13 CEST 2011

I was wondering if there was a stock function or package in Haskell that
allows you to map over a list, but short-circuits the mapping if any of
the calculations fail. Say, something like this:

-- Don't know if this is a valid signature! :)
mapThatCanFail :: (b -> Either a b) -> [b] -> Either a [b]

The idea being that, if any calculations fail, the function doesn't
bother mapping the rest of the list, but just returns a Left value
(error). Otherwise, it returns a Right value containing the new list.

I suppose I could try to implement that myself, but it seems like the
sort of thing that someone would have thought of already.


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