Data.Edison.Prelude

This module is a central depository of common definitions used throughout Edison.

Hashing classes

class Eq a => Hash a where

This class represents hashable objects. If obeys the following invariant:

forall x,y :: a. (x == y) implies (hash x == hash y)

Methods

hash :: a -> Int

class Hash a => UniqueHash a

This class represents hashable objects where the hash function is unique (injective). There are no new methods, just a stronger invariant:

forall x,y :: a. (x == y) iff (hash x == hash y)

class UniqueHash a => ReversibleHash a where

This class represents hashable objects where the hash is reversible.

forall x :: a. unhash (hash x) == x

Note that:

hash (unhash i) == i

does not necessarily hold because unhash is not necessarily defined for all i, only for all i in the range of hash.

Methods

unhash :: Int -> a

class Monoid v => Measured v a | a -> v where

This class represents a quantity that can be measured. It is calculated by an associative function with a unit (hence the Monoid superclass, and by a function which gives the measurement for an individual item. Some datastructures are able to speed up the calculation of a measure by caching intermediate values of the computation.

Methods

measure :: a -> v