Recent questions tagged Haskell

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haskell - how to increment a variable in functional programming

How do you increment a variable in a functional programming language? For example, I want to do: main :: IO () ... 1 print i Expected output: 1. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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haskell - List of different types?

data Plane = Plane { point :: Point, normal :: Vector Double } data Sphere = Sphere { center :: Point, radius :: Double } ... 0.5, 0.6, 0.2] } ] See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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haskell - Cabal not installing dependencies when needing profiling libraries?

I want to compile my program with profiling, so I run: $ cabal configure --enable-executable-profiling ... $ ... it does for normal libraries? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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663 views

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haskell - Splitting list into a list of possible tuples

I need to split a list into a list of all possible tuples, but I'm unsure of how to do so. For example: pairs ["cat"," ... | m <- [x], n <- xs] See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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656 views

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haskell - Distinction between typeclasses MonadPlus, Alternative, and Monoid?

The standard-library Haskell typeclasses MonadPlus, Alternative, and Monoid each provide two methods with ... superclass constraints? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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538 views

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haskell - Zipper Comonads, Generically

Given any container type we can form the (element-focused) Zipper and know that this structure is a Comonad. ... Is this instance even possible? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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825 views

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haskell - What part of Hindley-Milner do you not understand?

I swear there used to be a T-shirt for sale featuring the immortal words: What part of do you not understand? ... means, that would be helpful. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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815 views

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haskell - Unwrapping a monad

Given the below program, I am having issues dealing with monads. module Main where import System.Environment import ... doc/html/Text-CSV.html See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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845 views

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haskell - Is monad bind (>>=) operator closer to function composition (chaining) or function application?

In many articles I have read that monad >>= operator is a way to represent function composition. But for me it is ... a -> m c Please clarify. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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haskell - Is there a way to see the list of functions in a module, in GHCI?

I find it handy in Python or Common Lisp that you can list a library's contents at runtime. Does Haskell ... in particular from a GHCI prompt? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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665 views

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haskell - How to infer the type of an expression manually

Given ist the Haskell function: head . filter fst The question is now how to find the type "manually" by hand. ... easy to select the best one! See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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783 views

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haskell - Why doesn't TypeSynonymInstances allow partially applied type synonyms to be used in instance heads?

I know that TypeSynomymInstances only allows fully applied type synonyms to be used in instance heads, but it seems like it ... 1 "two" 3 4 5 See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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733 views

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haskell - Library function to compose a function with itself n times

Is there a library function available in Haskell to compose a function with itself n times? For example I ... about any intermediate results. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.2k views

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haskell - No instance for (Fractional Int) arising from a use of `/'

I am new to Haskell, and I am struggling with debugging my code. Fixing an error leads to other errors... Here ... time... Thank you very much. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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592 views

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haskell - How does Data.MemoCombinators work?

I've been looking at the source for Data.MemoCombinators but I can't really see where the heart of it is. ... of how it works in general. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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