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basic substitution implemented

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jingus 2026-05-15 19:00:37 -05:00
parent f64bf8be2b
commit fee6a0e4a3
2 changed files with 27 additions and 4 deletions
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17
test/EvaluationSpec.hs
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@ -1,8 +1,19 @@
module EvaluationSpec (spec) where
import Evaluation (subst)
import Parser (Expr (Abstraction, Application, Variable))
import Test.Hspec
spec :: Spec
spec = do
describe "Evaluation" $ do
it "can evaluation expressions" $
True `shouldBe` True
describe "subst" $ do
it "cannot substitute mismatched variables" $
subst (Variable "x") "y" (Variable "z") `shouldBe` Variable "x"
it "can substitute matched variables" $
subst (Variable "x") "x" (Variable "z") `shouldBe` Variable "z"
it "can substitute nested variables" $
subst absWithZ "z" absI `shouldNotBe` absWithZMaker absI
where
absWithZMaker z = Abstraction "x" (Application z (Variable "x"))
absWithZ = absWithZMaker (Variable "z")
absI = Abstraction "i" (Variable "i")