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Personal tools Home Log in ?php $this->data['sitenotice'] = 'This is a test instance. Do not edit, your changes will be lost.'; ? Views Page Discussion View source History Jump to: navigation , search start content The Zipper is an idiom that uses the idea of “context” to the means of manipulating locations in a data structure. Zipper monad is a monad which implements the zipper for binary trees. 1 Automation 2 Alternative formulation 3 Comonads and monads 4 Applications 5 Further reading Sometimes you want to manipulate a location inside a data structure, rather than the data itself. For example, consider a simple binary tree type: data Tree a = Fork ( Tree a ) ( Tree a ) | Leaf a and a sample tree t: t = Fork ( Fork ( Leaf 1 ) ( Leaf 2 ) ) ( Fork ( Leaf 3 ) ( Leaf 4 ) ) Each subtree of this tree occupies a certain l...

Instant is off Search plugin Manual haskell.org run Packages text fgl QuickCheck base bytestring run :: (forall s. ST s (MArray s)) -> Array text Data.Text.Array Run an action in the ST monad and return an immutable array of its result. run :: (DynGraph g, Ord a) => g a b -> NodeMapM a b g r -> (r, (NodeMap a, g a b)) fgl Data.Graph.Inductive.NodeMap Run a construction; return the value of the computation, the modified NodeMap , and the modified Graph . run :: Monad m => m a -> PropertyM m a QuickCheck Test.QuickCheck.Monadic run InBoundThread :: IO a -> IO a base Control.Concurrent Run the IO computation passed as the first argument. If the calling thread is not bound , a bound thread is created temporarily. runInBoundThread doesn't finish until the IO computation finishes. You can wrap a series of foreign function calls that rely on thread-local state w...

Tom Pledger [email protected] Fri, 12 Oct 2001 08:02:45 +1300 Previous message: performUnsafeIO Next message: help for exercise 4.10 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Sebastian Schulz writes: | hi. | | I need to extract an IO String to String. | Remembering some function like 'performUnsafeIO :: IO a -> a', I | searched the hugs libs, but without a match. | | Does a function like this still exists? It (unsafePerformIO) still exists. | Or how can I transform IO a to a? There's a safer way: http://haskell.org/wiki/wiki?ThatAnnoyingIoType Previous message: performUnsafeIO Next message: help for exercise 4.10 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] ...

Personal tools Home Log in Views Page Discussion View source History Jump to: navigation , search A quick introduction to QuickCheck, and testing Haskell code. See Introduction to QuickCheck2 for the QC2 version 1 Motivation 2 Keeping things pure 3 Testing with QuickCheck 4 Testing take5 5 Another property 6 Coverage 7 Going further 1 Motivation In September 2006, Bruno Martínez asked the following question: -- I've written a function that looks similar to this one getList = find 5 where find 0 = return [ ] find n = do ch <- getChar if ch ` elem ` [ 'a' .. 'e' ] then do tl <- find ( n - 1 ) return ( ch : tl ) else find n -- I want to test this function, without hitting the filesystem. In C++ I -- would use a istringstream. I couldn't find a function that returns a -- Handle from a String. The closer thing that may wor...

Personal tools Home Log in ?php $this->data['sitenotice'] = 'This is a test instance. Do not edit, your changes will be lost.'; ? Views Page Discussion View source History Jump to: navigation , search start content Cloud Haskell is a library for distributed concurrency in Haskell. The purpose is to make it easier to write programs for clusters of machines. It provides a message passing communication model, inspired by and very similar to that of Erlang. 1 Availability 2 Videos and Blog Posts 3 Papers 4 Documentation and Support 5 Current Status 6 Contributing 7 Semantics 8 Other Useful Packages 8.1 Serializable 9 Migration from remote 1 Availability Cloud Haskell is available from Hackage as distributed-process . You will probably also want to install a backend: The distributed-process-simplelocalnet backend is designed to ...

Personal tools Home Log in ?php $this->data['sitenotice'] = 'This is a test instance. Do not edit, your changes will be lost.'; ? Views Page Discussion View source History Jump to: navigation , search start content 1 Criticism 1.1 Didactics 1.2 Library design 1.3 Safety 2 Happy with less sugar 2.1 Additional combinators 2.2 Alternative combinators 3 Useful applications 4 See also 1 Criticism Haskell's do notation is popular and ubiquitous. However we shall not ignore that there are several problems. Here we like to shed some light on aspects you may not have thought about, so far. 1.1 Didactics The do notation hides functional details. This is wanted in order to simplify writing imperative style code fragments. The downsides are that, since do notation is used almost everywhere, where IO takes place, newcomers quickly bel...