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📝 Env stuff.

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Rob Rix 2017-09-13 15:48:02 -04:00
parent b118bb5b38
commit 89f7101e27
1 changed files with 3 additions and 0 deletions
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src/Data/Functor/Binding.hs
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@ -69,12 +69,15 @@ letBind diff f = embed (Let (Env [(n, diff)]) body)
n = maybe (Metavar 0) succ (foldMaxMap maxBoundMetavariable body) n = maybe (Metavar 0) succ (foldMaxMap maxBoundMetavariable body)
-- | An environment, binding 'Metavar'iables to values.
newtype Env a = Env { unEnv :: [(Metavar, a)] } newtype Env a = Env { unEnv :: [(Metavar, a)] }
deriving (Eq, Foldable, Functor, Monoid, Ord, Semigroup, Show, Traversable) deriving (Eq, Foldable, Functor, Monoid, Ord, Semigroup, Show, Traversable)
-- | Extend an 'Env' by binding a 'Metavar'iable to a value.
envExtend :: Metavar -> a -> Env a -> Env a envExtend :: Metavar -> a -> Env a -> Env a
envExtend var val (Env m) = Env ((var, val) : m) envExtend var val (Env m) = Env ((var, val) : m)
-- | Lookup the given 'Metavar'iable in an 'Env'.
envLookup :: Metavar -> Env a -> Maybe a envLookup :: Metavar -> Env a -> Maybe a
envLookup var = lookup var . unEnv envLookup var = lookup var . unEnv