copilot/examples/Engine.hs

-- Copyright © 2011 National Institute of Aerospace / Galois, Inc.

-- | Example implementing an engine cooling control system.

{-# LANGUAGE RebindableSyntax #-}

module Main where

import Language.Copilot
import qualified Prelude as P

-- If the majority of the engine temperature probes exeeds 250 degrees, then
-- the cooler is engaged and remains engaged until the majority of the engine
-- temperature probes drop to 250 or below.  Otherwise, trigger an immediate
-- shutdown of the engine.

engineMonitor :: Spec
engineMonitor = do
  trigger "shutoff" (not ok) [arg maj]

  where
  vals     = [ externW8 "tmp_probe_0" two51
             , externW8 "tmp_probe_1" two51
             , externW8 "tmp_probe_2" zero]
  exceed   = map (> 250) vals
  maj      = majority exceed
  checkMaj = aMajority exceed maj
  ok       = alwaysBeen ((maj && checkMaj) ==> extern "cooler" cooler)

  two51  = Just $ [251, 251] P.++ repeat (250 :: Word8)
  zero   = Just $ repeat (0 :: Word8)
  cooler = Just $ [True, True] P.++ repeat False

main :: IO ()
main = interpret 10 engineMonitor