ruler-core-1.0: examples/Internal.rul

{
{-# LANGUAGE BangPatterns #-}
module Internal where

import Control.Monad.Error
}

data D
  con C

itf D
  visit dispatch
    inh ast :: D
    syn x :: Int
    syn z :: Int

{
foo =
 sem foo : D monad IO
  visit dispatch
   clause C
    internal bla   -- internal clause: conditionally compute attributes
      loc.p = 9
      lhs.z = loc.p
      clause other1
        match False = True  -- this clause will fail
        loc.q = True
        lhs.x = loc.p + const 3 lhs.ast
      clause other2
        lhs.x = 42          -- the result of this internal clause is returned
}

{
test :: D -> IO (Int, Int)
test d = do
  let inh = Inh_D_dispatch { ast_Inh_D = d }
  syn <- invoke_D_dispatch foo inh
  let x = x_Syn_D syn
  let z = z_Syn_D syn
  return (x,z)

main :: IO ()
main = do let d = D_C
          t <- test d
          putStrLn $ show t
}