Documentation

This handler stores a polymorphic function that returns a different type.

let y = pick (5 :: Int) :: Which '[Int, Bool]
switch y (CaseFunc @Typeable (show . typeRep . (pure @Proxy))) `shouldBe` Int

let x = (5 :: Int) ./ False ./ 'X' ./ Just 'O' ./ (6 :: Int) ./ Just 'A' ./ nul
afoldr (:) [] (forMany (CaseFunc @Typeable (show . typeRep . (pure @Proxy))) x) `shouldBe`
    ["Int", "Bool", "Char", "Maybe Char", "Int", "Maybe Char"]

This handler stores a polymorphic function that doesn't change the type.

let x = (5 :: Int) ./ (6 :: Int8) ./ (7 :: Int16) ./ (8 :: Int32) ./ nil
    y = (15 :: Int) ./ (16 :: Int8) ./ (17 :: Int16) ./ (18 :: Int32) ./ nil
afmap (CaseFunc' @Num (+10)) x `shouldBe` y