category-theory

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Scala -- How to use Functors on non-Function types?

While reading the description of Functors on this blog: https://hseeberger.wordpress.com/2010/11/25/introduction-to-category-theory-in-scala/[详细]

2023-04-08 07:52 分类：问答
Functor is for (a -> b) -> (f a -> f b), what is for (Category c) => c a b -> c (f a) (f b)?

I would like to have a function for either mapping a pure function to a container or sequencing applicative/monadic action through it. For pure mapping we have[详细]

2023-03-14 22:35 分类：问答
Representable Functor isomorphic to (Bool -> a)

I thought I\'d try the intriguing Representable-functors package to define a Monad and Comonad instance for the functor given by data Pair a = Pair a a which is representable by Bool; as mentioned in[详细]

2023-03-09 01:49 分类：问答
NonEmpty isn't a Comonad?

Why is the NonEmpty 开发者_Python百科list from the semigroups package not also an instance of the comonad class?It is. The instance is just defined in the comonad package, and not the semigroups packa[详细]

2023-03-08 20:23 分类：问答
Haskell: How is join a natural transformation?

I开发者_运维知识库 can define a natural transformation in Haskell as: h :: [a] -> Maybe a h []= Nothing[详细]

2023-03-03 15:42 分类：问答
A monad is just a monoid in the category of endofunctors, what's the problem?

Who first said the following? A monad is just a monoid in the category of endofunctors, what\'s the problem?[详细]

2023-01-19 01:48 分类：问答
Are all Haskell functors endofunctors?

I\'m a bit confused, and need someone to set me straight. Lets outline my current understanding: Where E is an endofunctor, and A is some category:[详细]

2023-01-07 13:38 分类：问答
Can liftM differ from liftA?

According to the Typeclassopedia (among other sources), Applicative logically belongs between Monad and Pointed (and thus Functor) in the type class hierarchy, so we would ideally have something like[详细]

2022-12-09 10:24 分类：问答