[Haskell-cafe] Thompson's Exercise 9.13
daniel.is.fischer at web.de
Sun Apr 10 14:02:27 EDT 2005
Am Sonntag, 10. April 2005 19:46 schrieb Daniel Fischer:
> > so it doesn't work in all cases. The idea is nice, though:
> > import Data.Maybe
> > finit = catMaybes . foldr f [Nothing] . map Just
> > where
> > f x ys = case ys of
> > [Nothing] -> 
> > _ -> x:ys
> > will do fine.
> Ooooops, only for nonempty lists!
Replace catMaybes with 'map (maybe (error "init of ") id)'
and it'll work also for empty lists.
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