Re: [Haskell-cafe] Does this function have a name?

7 Apr 2017

      Oops, there's a free variable in there, let me fix it:

first f [] = Nothing
first f (x:xs) = fmap (:xs) (f x) <|> fmap (x:) (first f xs)

Paul

On Fri, Apr 7, 2017 at 10:42 AM Paul Brauner  wrote:
...
Hello Haskell Cafe,
I had to write the following function and I was wondering if it (or its
generalization to Alternative or Traversable) was exposed by some library
under a different name:
first [] = Nothing
first (t:ts) = fmap (:ts) (s t) <|> fmap (t:) (first ts)
Somehow it is to "traverse" as "any" is to "all".
Cheers,
Paul