Poly.hs

{-# LANGUAGE ExplicitNamespaces #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Dimensions.Poly
-- Copyright   :  (C) 2013 Richard Eisenberg
-- License     :  BSD-style (see LICENSE)
-- Maintainer  :  Richard Eisenberg (eir@cis.upenn.edu)
-- Stability   :  experimental
-- Portability :  non-portable
--
-- This module exports all of the definitions you need if you wish to
-- write functions polymorphic over dimension specifications.
--
-- Each dimensioned quantity is represented by a member of the type
-- 'Dim', which is parameterized by a type-level list of 'DimSpec's.
-- A 'DimSpec', in turn, is a unit type paired with its exponent,
-- representented with a type-level 'Z'. The unit types should all be
-- /canonical/ -- that is, the "base" unit of all compatible units. Thus,
-- the type of velocity in the SI system would be
-- @Dim '[D Meter One, D Second MOne]@.
--
-- A technical detail: because 'DimSpec' is used only at the type level
-- and needs to store types of kind @*@, it must be parameterized, as we
-- can't specify @*@ in its declaration. (See \"The Right Kind of Generic
-- Programming\", by José Pedro Magalhães, published at WGP'12, for more
-- explanation.) So, we always work with @(DimSpec *)@s.
----------------------------------------------------------------------------

module Data.Dimensions.Poly (
  -- * The 'Dim' type
  Dim,

  -- * Maniuplating dimension specifications
  DimSpec(..), type ($=), Extract, Reorder, type (@~), Normalize,
  type (@+), type (@-), NegDim, NegList, type (@*), type (@/)

  ) where

import Data.Dimensions.Dim
import Data.Dimensions.DimSpec