monads

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Equivalent of Haskell do-notation or F# Computation Expressions in Scala?

F# Computation Expressions allow to hide the complexity of monadic syntax behind a thick layer of syntactic sugar. Is there something similar available in Scala?[详细]

2023-04-06 05:22 分类：问答
Haskell frustration with function calls

Learning Haskell is killing me. If I am going to write a function that takes an array of arrays of order-able elements, and outputs the same thing, how do I do that?[详细]

2023-04-06 03:30 分类：问答
Folding across Maybes in Haskell

In an attempt to learn Haskell, I have come across a situation in which I wish to do a fold over a list but my accumulator is a Maybe. The function I\'m folding with however takes in the \"extracted\"[详细]

2023-04-05 12:57 分类：问答
Why do we have map, fmap and liftM?

map :: (a -> b) -> [a] -> [b]开发者_C百科 fmap :: Functor f => (a -> b) -> f a -> f b[详细]

2023-04-05 12:37 分类：问答
Help me understand this Scala code: scalaz IO Monad

Here\'s the code I\'m trying to understand (it\'s from http://apocalisp.wordpress.com/2010/10/17/scalaz-tutorial-enumeration-based-io-with-iteratees/):[详细]

2023-04-04 09:21 分类：问答
Asymmetry in the bind function

ghci> :t (>>=) (>>=) :: Monad m => m a -> (a -> m b) -> m b How come the second argument is (a -> m b) instead of (m a -> m b) or even (a -> b)? What is it concep[详细]

2023-04-03 12:05 分类：问答
How to take out a value out of a monad in Haskell?

Is there any way to take \"things\" out of a monad? I am developing a game, and I am now trying to understand about databases. I found happstack really nice, but I can\'t get the thing.[详细]

2023-04-02 23:56 分类：问答
monads-tf: MonadReader instance for MonadState

Consider the next example. I have a monad MyM that is just a StateT {-# LANGUAGE TypeFamilies #-} import Control.Monad.State[详细]

2023-04-02 20:01 分类：问答
Calling an IO Monad inside an Arrow

Perhaps I\'m going about this the wrong way, but I\'m using HXT to read in some vertex data that I\'d like to use in an array in HOp开发者_如何学编程enGL. Vertex arrays need to be a Ptr which is creat[详细]

2023-04-01 01:47 分类：问答
Haskell: What monad did I just reinvent?

I just reinvented some monad, but I\'m not sure which.It lets you model steps of a computation, so you can interleave the steps of numerous computations to find which one finishes first.[详细]

2023-03-31 21:33 分类：问答