sequence in haskell

the type signature of sequence in Haskell is

sequence :: (Monad m, Traversable t) => t (m a) -> m (t a)

so I could have sequence [Left 4, Right 5] => Left 4

and sequence [Right 6, Right 9] => Right [6,9]

Is there an equivalent in sanctuary? I’ve been scanning libraries that implement the fantasy-land spec, none of them seem to have this (so far)

Edit : I understand it can be implemented as such (atleast for my task at hand) x => S.reduce(S.lift2(S.C(S.append)),S.Right([]),x), was wondering why something as such is missing

[davidchambers]

Here are the Sanctuary equivalents of your Haskell expressions, @functor-soup, on the dc-fantasy-land branch:

> S.sequence
sequence :: (Applicative f, Traversable t) => TypeRep f -> t (f b) -> f (t b)

> S.sequence(S.Either, [S.Left(4), S.Right(5)])
Left(4)

> S.sequence(S.Either, [S.Right(6), S.Right(9)])
Right([6, 9])

I’ll close this issue as I believe we’ve answered your question. 😃

[joneshf]

λ: :t sequenceA [Left 4, Right 5]
sequenceA [Left 4, Right 5] :: (Num a1, Num a) => Either a1 [a]