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implementation module Snug.Syntax
import qualified Data.Set
from Data.Set import :: Set
import StdEnv
none = 'Data.Set'.newSet
instance usedSymbols [a] | usedSymbols a
where
usedSymbols xs = 'Data.Set'.unions (map usedSymbols xs)
instance usedSymbols (a, b) | usedSymbols a & usedSymbols b
where
usedSymbols (x,y) = 'Data.Set'.union (usedSymbols x) (usedSymbols y)
instance usedSymbols CaseAlternative
where
usedSymbols (CaseAlternative pat expr) =
'Data.Set'.difference (usedSymbols expr) (usedSymbols pat)
instance usedSymbols Expression
where
usedSymbols (BasicValue _) = none
usedSymbols (Symbol sym) = none
usedSymbols (Constructor _) = none
usedSymbols (Case e alts) = usedSymbols (e, alts)
usedSymbols (ExpApp e1 e2) = usedSymbols (e1, e2)
instance usedSymbols Pattern
where
usedSymbols Wildcard = none
usedSymbols (BasicValuePattern _) = none
usedSymbols (IdentPattern id) = 'Data.Set'.singleton id
usedSymbols (ConstructorPattern _ syms) = 'Data.Set'.fromList syms
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