Control.Monad.Fresh

Computations that need a fresh name supply.

MonadFresh class

class (Applicative m, Monad m) => MonadFresh m where

Methods

freshIdent

Arguments

:: String

Desired name

-> m Integer

Get the integer of the next fresh identifier of this name.

freshIdents

Arguments

:: Integer

Number of desired fresh identifiers.

-> m Integer

The first Fresh identifier.

Get a number of fresh identifiers. This reserves the required number of identifiers on all names.

scopeFreshness :: m a -> m a

Scope the freshIdent and freshIdents requests such that these variables are not marked as used once the scope is left.

Instances

MonadFresh m => MonadFresh (MaybeT m)

(Functor m, Monad m) => MonadFresh (FreshT m)

(Functor m, Monad m) => MonadFresh (FreshT m)

MonadFresh m => MonadFresh (ReaderT r m)

MonadFresh m => MonadFresh (StateT s m)

(Monoid w, MonadFresh m) => MonadFresh (WriterT w m)

The Fresh monad

type Fresh = FreshT Identity

runFresh :: Fresh a -> FreshState -> (a, FreshState)

Run a computation with a fresh name supply.

evalFresh :: Fresh a -> FreshState -> a

Evaluate a computation with a fresh name supply.

execFresh :: Fresh a -> FreshState -> FreshState

Execute a computation with a fresh name supply.

The fast FreshT monad transformer

newtype FreshT m a

A computation that can generate fresh variables from name hints.

Constructors

FreshT

Fields

unFreshT :: StateT FreshState m a

Instances

MonadTrans FreshT

MonadBind k v m => MonadBind k v (FreshT m)

MonadError e m => MonadError e (FreshT m)

MonadReader r m => MonadReader r (FreshT m)

MonadState s m => MonadState s (FreshT m)

Monad m => Monad (FreshT m)

Functor m => Functor (FreshT m)

MonadPlus m => MonadPlus (FreshT m)

(Monad m, Functor m) => Applicative (FreshT m)

(Functor m, MonadPlus m) => Alternative (FreshT m)

(Functor m, Monad m) => MonadFresh (FreshT m)

MonadDisj m => MonadDisj (FreshT m)

freshT :: (FreshState -> m (a, FreshState)) -> FreshT m a

Construct a FreshT action from a FreshState modification.

runFreshT :: FreshT m a -> FreshState -> m (a, FreshState)

Run a computation with a fresh name supply.

evalFreshT :: Monad m => FreshT m a -> FreshState -> m a

Evaluate a computation with a fresh name supply.

execFreshT :: Monad m => FreshT m a -> FreshState -> m FreshState

Execute a computation with a fresh name supply.

Fresh name generation

type FreshState = Integer

The state of the name supply: the first unused sequence number of every name.

nothingUsed :: FreshState

The empty fresh state.

module Control.Monad.Trans