Answer by yfeldblum for What is [] (list constructor) in Haskell?
The type is described (in a GHCI session) as:$ ghciPrelude> :info []data [] a = [] | a : [a] -- Defined We may also think about it as though it were defined as:data List a = Nil | Cons a (List...
View ArticleAnswer by C. A. McCann for What is [] (list constructor) in Haskell?
Just to make things more explicit, this data type:data List a = Cons a (List a) | Nil...has the same structure as the built-in list type, but without the (nicer, but potentially confusing) special...
View ArticleAnswer by Don Stewart for What is [] (list constructor) in Haskell?
it is a type constructor (e.g. [Int] is a type), and a data constructor ([2] is a list structure).The empty list is a list holding any type[a] is like Maybe a, [2] is like Just 2.[] is a zero-ary...
View ArticleAnswer by Doug McClean for What is [] (list constructor) in Haskell?
It's (confusingly, I'll grant you) syntactically overloaded to be both a type constructor and a value constructor.It means that (the value constructor) [] has the type that, for all types a, it is a...
View ArticleWhat is [] (list constructor) in Haskell?
I'm Having problems understanding functors, specifically what a concrete type is in LYAH. I believe this is because I don't understand what [] really is.fmap :: (a -> b) -> f a -> f b Is [], a...
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