Control.Monad.Trans.PreciseFresh

A monad transformer for passing a fresh name supply through a computation. The name supply is precise in the sense that every String has its own supply of indices for the next fresh name.

Modeled after the mtl-2.0 library.

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 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)

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

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

Execute a computation with a fresh name supply.

Fresh name generation

type FreshState = Map String Integer

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

nothingUsed :: FreshState

The empty fresh state.

freshIdent :: Monad m => String -> FreshT m Integer

O(log(n)). Get a fresh identifier for the given name.

freshIdents

Arguments

:: Monad m

=> Integer

number of desired identifiers

-> FreshT m Integer

The first fresh identifier.

O(n). Get k fresh identifiers.

scopeFreshness :: Monad m => FreshT m a -> FreshT m a

Restrict the scope of the freshness requests.