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Hash

Contents The HashTable type Operations on HashTables The Hash class

Description

Implementation of fixed-size hash tables, with a type class for constructing hash values for structured types.

Synopsis

data HashTable key val new :: (Eq key, Hash key) => Int -> IO (HashTable key val) insert :: (Eq key, Hash key) => key -> val -> IO () lookup :: Hash key => key -> IO (Maybe val) class Hash a where hash :: a -> Int

The HashTable type

data HashTable key val

A hash table with keys of type key and values of type val. The type key should be an instance of Eq.

Operations on HashTables

new :: (Eq key, Hash key) => Int -> IO (HashTable key val)

Builds a new hash table with a given size

insert :: (Eq key, Hash key) => key -> val -> IO ()

Inserts a new element into the hash table

lookup :: Hash key => key -> IO (Maybe val)

Looks up a key in the hash table, returns Just val if the key was found, or Nothing otherwise.

The Hash class

class Hash a where

A class of types which can be hashed. Methods hash :: a -> Int hashes the value of type a into an Int Instances Hash Float Hash Int (Hash a, Hash b) => Hash ((,) a b)

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