**Packages**- base
- stm
- package
- mtl
- transformers

Software Transactional Memory: a modular composable concurrency abstraction. See
* *Composable memory transactions*, by Tim Harris, Simon Marlow, Simon Peyton Jones, and Maurice Herlihy, in /ACM Conference on Principles and Practice of Parallel Programming/ 2005. http://research.microsoft.com/Users/simonpj/papers/stm/index.htm
This module only defines the STM monad; you probably want to import Control.Concurrent.STM (which exports Control.Monad.STM).

A monad supporting atomic memory transactions.

A monad transformer version of the ST monad Warning! This monad transformer should not be used with monads that can contain multiple answers, like the list monad. The reason is that the will be duplicated across the different answers and this cause Bad Things to happen (such as loss of referential transparency). Safe monads include the monads State, Reader, Writer, Maybe and combinations of their corresponding monad transformers.
Version 0.3.1

Strict RWS monad.
Inspired by the paper *Functional Programming with Overloading and Higher-Order Polymorphism*, Mark P Jones (http://web.cecs.pdx.edu/~mpj/) Advanced School of Functional Programming, 1995.

State monads.
This module is inspired by the paper *Functional Programming with Overloading and Higher-Order Polymorphism*, Mark P Jones (http://web.cecs.pdx.edu/~mpj/) Advanced School of Functional Programming, 1995.

Strict state monads.
This module is inspired by the paper *Functional Programming with Overloading and Higher-Order Polymorphism*, Mark P Jones (http://web.cecs.pdx.edu/~mpj/) Advanced School of Functional Programming, 1995.

A monad transformer that combines ReaderT, WriterT and StateT. This version is strict; for a lazy version, see Control.Monad.Trans.RWS.Lazy, which has the same interface.

State monads, passing an updatable state through a computation.
Some computations may not require the full power of state transformers:
* For a read-only state, see Control.Monad.Trans.Reader.
* To accumulate a value without using it on the way, see Control.Monad.Trans.Writer.
This version is lazy; for a strict version, see Control.Monad.Trans.State.Strict, which has the same interface.

Strict state monads, passing an updatable state through a computation. See below for examples.
In this version, sequencing of computations is strict. For a lazy version, see Control.Monad.Trans.State.Lazy, which has the same interface.
Some computations may not require the full power of state transformers:
* For a read-only state, see Control.Monad.Trans.Reader.
* To accumulate a value without using it on the way, see Control.Monad.Trans.Writer.

The strict WriterT monad transformer, which adds collection of outputs (such as a count or string output) to a given monad.
This version builds its output strictly; for a lazy version, see Control.Monad.Trans.Writer.Lazy, which has the same interface.
This monad transformer provides only limited access to the output during the computation. For more general access, use Control.Monad.Trans.State instead.

Strict writer monads.
Inspired by the paper *Functional Programming with Overloading and Higher-Order Polymorphism*, Mark P Jones (http://web.cecs.pdx.edu/~mpj/pubs/springschool.html) Advanced School of Functional Programming, 1995.

Provides an unsafe API for inserting heterogeneous data in a collection keyed by StableNames and for later retrieving it.
Version 0.0.4

Whereas most memo combinators memoize based on equality, stable-memo does it based on whether the exact same argument has been passed to the function before (that is, is the same argument in memory).
* stable-memo only evaluates keys to WHNF.
* This can be more suitable for recursive functions over graphs with cycles.
* stable-memo doesn't retain the keys it has seen so far, which allows them to be garbage collected if they will no longer be used. Finalizers are put in place to remove the corresponding entries from the memo table if this happens.
* Data.StableMemo.Weak provides an alternative set of combinators that also avoid retaining the results of the function, only reusing results if they have not yet been garbage collected.
* There is no type class constraint on the function's argument.
stable-memo will not work for arguments which happen to have the same value but are not the same heap object. This rules out many candidates for memoization, such as the most common example, the naive Fibonacci implementation whose domain is machine Ints; it can still be made to work for some domains, though, such as the lazy naturals.
> data Nat = Succ Nat | Zero
> fib :: Nat -> Integer
> fib = memo fib'
> where fib' Zero = 0
> fib' (Succ Zero) = 1
> fib' (Succ n1@(Succ n2)) = fib n1 + fib n2
Below is an implementation of map that preserves sharing of the spine for cyclic lists. It should even be safe to use this on arbitrarily long, acyclic lists since as long as the garbage collector is chasing you, the size of the memo table should stay under control, too.
> map :: (a -> b) -> [a] -> [b]
> map f = go
> where go = memo map'
> map' [] = []
> map' (x:xs) = f x : go xs
This library is largely based on the implementation of memo found in "Stretching the storage manager: weak pointers and stable names in Haskell", from Simon Peyton Jones, Simon Marlow, and Conal Elliott (http://community.haskell.org/~simonmar/papers/weak.pdf).
Version 0.2.2

Fundamental * -> * types, operators, and covariant instances.
Version 1.0

Contravariant instances for the fundamental * -> * types and operators.
Version 1.0

A haskell memcached client. See http://memcached.org for more information.
This implements the new binary protocol, so it only works with memcached version 1.3 and newer.
Version 0.3.0

Space simulation game.
Version 0.1.1

transformers Control.Monad.Trans.State.Lazy, transformers Control.Monad.Trans.State.Strict, mtl Control.Monad.State.Lazy, mtl Control.Monad.State.Strict

A state monad parameterized by the type s of the state to carry.
The return function leaves the state unchanged, while >>= uses the final state of the first computation as the initial state of the second.

Construct a state monad computation from a state transformer function.