haskell

问题 I’d like to split a string using a regular expression. I have browsed the various regex modules on Hackage, but I can’t make any sense of them. (I have noticed Data.List.Split , but it doesn’t seem to offer what I need, either.) 回答1: This may help you: ghci > import Text.Regex.Posix ghci > getAllTextMatches ("good food" =~ ".ood" :: AllTextMatches [] String) ["good","food"] Real world haskell book has a nice chapter on it. 来源： https://stackoverflow.com/questions/20128557/how-do-i-split-a

问题 I’d like to split a string using a regular expression. I have browsed the various regex modules on Hackage, but I can’t make any sense of them. (I have noticed Data.List.Split , but it doesn’t seem to offer what I need, either.) 回答1: This may help you: ghci > import Text.Regex.Posix ghci > getAllTextMatches ("good food" =~ ".ood" :: AllTextMatches [] String) ["good","food"] Real world haskell book has a nice chapter on it. 来源： https://stackoverflow.com/questions/20128557/how-do-i-split-a

问题 The bounty expires tomorrow . Answers to this question are eligible for a +500 reputation bounty. Damián Rafael Lattenero is looking for a canonical answer : Maybe it could be a generalisation of arity in methods requiring multiple typed arguments. Two Main Problems to solve: 1) Type check is lost Using the array argument Single.zip() version I lose the strongly typed arguments. 2) Source argument Cannot be Nullable I cannot send nullable source values as argument of Single.zip() function 3)

问题 It is widely known that Applicative generalises Arrows . In the Idioms are oblivious, arrows are meticulous, monads are promiscuous paper by Sam Lindley, Philip Wadler and Jeremy Yallop it is said that Applicative is equivalent to Static Arrows, that is arrows for which the following isomorphism holds: arr a b :<->: arr () (a -> b) As far as I can understand, it could be illustrated the following way: Note: newtype Identity a = Id { runId :: a } . Klesli Identity is a Static Arrow as it wraps

问题 My ghci version is 8.4.3 I tried stack install QuickCheck Something was installed. But when I input import Test.QuickCheck , it tells Could not find module ‘Test.QuickCheck’ again. How can I fix it? 回答1: Firstly, stack install is not recommended for installing executables or libraries. Instead, there's a couple of things you can do to use the QuickCheck library: If you want to use QuickCheck in a command such as stack ghci or stack ghc , you can add it as a --package option e.g. to run a REPL

问题 I recently started using Haskell and it will probably be for a short while. Just being asked to use it to better understand functional programming for a class I am taking at Uni. Now I have a slight problem I am currently facing with what I am trying to do. I want to build it breadth-first but I think I got my conditions messed up or my conditions are also just wrong. So essentially if I give it [“A1-Gate”, “North-Region”, “South-Region”, “Convention Center”, “Rectorate”, “Academic Building1”

问题 I recently started using Haskell and it will probably be for a short while. Just being asked to use it to better understand functional programming for a class I am taking at Uni. Now I have a slight problem I am currently facing with what I am trying to do. I want to build it breadth-first but I think I got my conditions messed up or my conditions are also just wrong. So essentially if I give it [“A1-Gate”, “North-Region”, “South-Region”, “Convention Center”, “Rectorate”, “Academic Building1”

问题 I recently upgraded to Cabal 3.2 (and GHC 8.10) and I am running into some major issues that make some of my project non-buildable anymore... Thorough description of the problem Here is a minimal (not) working configuration that fails every time: I start off with a clean Cabal configuration (by deleting ~/.cabal ); the reason for that will appear later in the post. I run cabal update to recreate the .cabal directory and to ensure Cabal is working. I create a project (let's call it test1 )

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Closed 6 years ago . Locked . This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions. I've searched on the Internet for comparisons between F# and Haskell but haven't found anything really definitive. What are the primary differences and why would I want to choose one over the other? 回答1: Haskell

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Closed 6 years ago . Locked . This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions. I've searched on the Internet for comparisons between F# and Haskell but haven't found anything really definitive. What are the primary differences and why would I want to choose one over the other? 回答1: Haskell