ghc-7.10.3: The GHC API

Safe Haskell | None
Language | Haskell2010

UniqSupply

Contents

- Main data type
  - Operations on supplies
- Unique supply monad and its abstraction
  - Operations on the monad

Synopsis

- data UniqSupply
- uniqFromSupply :: UniqSupply -> Unique
- uniqsFromSupply :: UniqSupply -> [Unique]
- takeUniqFromSupply :: UniqSupply -> (Unique, UniqSupply)
- mkSplitUniqSupply :: Char -> IO UniqSupply
- splitUniqSupply :: UniqSupply -> (UniqSupply, UniqSupply)
- listSplitUniqSupply :: UniqSupply -> [UniqSupply]
- data UniqSM result
- class Monad m => MonadUnique m where
  - getUniqueSupplyM :: m UniqSupply
  - getUniqueM :: m Unique
  - getUniquesM :: m [Unique]
- initUs :: UniqSupply -> UniqSM a -> (a, UniqSupply)
- initUs_ :: UniqSupply -> UniqSM a -> a
- lazyThenUs :: UniqSM a -> (a -> UniqSM b) -> UniqSM b
- lazyMapUs :: (a -> UniqSM b) -> [a] -> UniqSM [b]

# Main data type

data UniqSupply

A value of type `UniqSupply` is unique, and it can supply one distinct `Unique`. Also, from the supply, one can also manufacture an arbitrary number of further `UniqueSupply` values, which will be distinct from the first and from all others.

## Operations on supplies

uniqFromSupply :: UniqSupply -> Unique

Obtain the `Unique` from this particular `UniqSupply`

uniqsFromSupply :: UniqSupply -> [Unique]

Obtain an infinite list of `Unique` that can be generated by constant splitting of the supply

takeUniqFromSupply :: UniqSupply -> (Unique, UniqSupply)

Obtain the `Unique` from this particular `UniqSupply`, and a new supply

mkSplitUniqSupply :: Char -> IO UniqSupply

Create a unique supply out of thin air. The character given must be distinct from those of all calls to this function in the compiler for the values generated to be truly unique.

splitUniqSupply :: UniqSupply -> (UniqSupply, UniqSupply)

Build two `UniqSupply` from a single one, each of which can supply its own `Unique`.

listSplitUniqSupply :: UniqSupply -> [UniqSupply]

Create an infinite list of `UniqSupply` from a single one

# Unique supply monad and its abstraction

data UniqSM result

A monad which just gives the ability to obtain `Unique`s

Instances

Monad UniqSM |
Functor UniqSM |
MonadFix UniqSM |
Applicative UniqSM |
MonadUnique UniqSM |

class Monad m => MonadUnique m where

A monad for generating unique identifiers

Minimal complete definition

getUniqueSupplyM

Methods

getUniqueSupplyM :: m UniqSupply

Get a new UniqueSupply

getUniqueM :: m Unique

Get a new unique identifier

getUniquesM :: m [Unique]

Get an infinite list of new unique identifiers

Instances

MonadUnique UniqSM |
MonadUnique CoreM |
MonadUnique SimplM |
MonadUnique TcS |

## Operations on the monad

initUs :: UniqSupply -> UniqSM a -> (a, UniqSupply)

Run the `UniqSM` action, returning the final `UniqSupply`

initUs_ :: UniqSupply -> UniqSM a -> a

Run the `UniqSM` action, discarding the final `UniqSupply`

lazyThenUs :: UniqSM a -> (a -> UniqSM b) -> UniqSM b

lazyMapUs :: (a -> UniqSM b) -> [a] -> UniqSM [b]