content: {-# LANGUAGE TemplateHaskell, TypeFamilies, TypeOperators #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Data.Units.US.Troy
  -- Copyright   :  (C) 2013 Richard Eisenberg
  -- License     :  BSD-style (see LICENSE)
  -- Maintainer  :  Richard Eisenberg (rae@cs.brynmawr.edu)
  -- Stability   :  experimental
  -- Portability :  non-portable
  --
  -- This module defines troy measures of mass. The troy
  -- system is most often used when measuring precious metals.
  --
  -- Included are all units mentioned here:
  -- <http://en.wikipedia.org/wiki/United_States_customary_units>
  -- Where possible, conversion rates have been independently verified
  -- at a US government website. However, Wikipedia's base is /much/
  -- better organized than any government resource immediately available.
  -- The US government references used are as follows:
  -- <http://nist.gov/pml/wmd/metric/upload/SP1038.pdf>
  -- <http://nist.gov/pml/wmd/pubs/upload/appc-14-hb44-final.pdf>
  -----------------------------------------------------------------------------
  
  module Data.Units.US.Troy (
    module Data.Units.US.Troy,
  
    -- | The avoirdupois grain is the same as the troy grain
    Grain(..)
    ) where
  
  import Data.Metrology.TH
  import Data.Units.US.Avoirdupois ( Grain(..) )
  
  import Language.Haskell.TH
  
  declareDerivedUnit "Pennyweight" [t| Grain       |] 24 (Just "dwt")
  declareDerivedUnit "Ounce"       [t| Pennyweight |] 20 (Just "ozt")
  declareDerivedUnit "Pound"       [t| Ounce       |] 12 (Just "lbt")
  
  -- | Includes 'Grain', 'Pennyweight', 'Ounce', and 'Pound'
  troyMassMeasures :: [Name]
  troyMassMeasures = [ ''Grain, ''Pennyweight, ''Ounce, ''Pound ]
  