Hi, Maybe is a type and Just is one of it's constructors (the other being Nothing):
data Maybe a = Just a | Nothing
On Sat, Dec 12, 2015 at 3:29 PM, Lim H.
Hi everyone,
Sorry if this email disturbs you. I haven't used a developer's mailing list before so I'm not sure if I'm violating any etiquette. If I do, please excuse me.
I'm trying to understand the type of sequence [Just, Just]. I can understand sequence [Just 1, Just 2] :: Num a => Maybe [a]
because when looking at the type of sequence
sequence :: (Monad m, Traversable t) => t (m a) -> m (t a)
it is clear that this function takes a collection of monadic values and return a single monadic value of the collection. Thus, when we call sequence [Just 1, Just 2] we should get back a Just of [1,2]. Following that train of thoughts, shouldn't sequence [Just, Just] return a single Just?
Here is the corresponding SO question
http://stackoverflow.com/questions/34244574/trouble-understanding-the-type-o...
Lim
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