content: {-# LANGUAGE TemplateHaskell, TypeFamilies, TypeOperators #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Data.Units.Imperial.Survey
  -- Copyright   :  (C) 2013 Richard Eisenberg
  -- License     :  BSD-style (see LICENSE)
  -- Maintainer  :  Richard Eisenberg (rae@cs.brynmawr.edu)
  -- Stability   :  experimental
  -- Portability :  non-portable
  --
  -- Survey units are Gunter's units, so called because thay have been
  -- standardised by Edmund Gunter in 1620 at 25 links to the rod, 4 rods
  -- to the chain.
  --
  -- Where possible, reference have been made to UK legislation. However,
  -- Wikipedia's page is /much/ better organized than any government
  -- resource immediately available.
  -----------------------------------------------------------------------------
  
  module Data.Units.Imperial.Survey where
  
  import Data.Metrology.TH
  
  import Data.Units.Imperial.Length
  
  import Language.Haskell.TH
  
  declareDerivedUnit "Rod"  [t| Chain |] 0.25 (Just "rd")
  declareDerivedUnit "Link" [t| Rod   |] 0.04 (Just "li")
  
  -- | Survey lengths: All units above
  surveyLengths :: [Name]
  surveyLengths = [ ''Link, ''Rod ]
  