buuka/test/Test/Data/Functor/Foldable.hs
2021-01-03 00:05:33 +02:00

69 lines
1.6 KiB
Haskell

{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE TemplateHaskell #-}
module Test.Data.Functor.Foldable where
import Hedgehog
import qualified Hedgehog.Gen as Gen
import qualified Hedgehog.Range as Range
import Test.Tasty
import Test.Tasty.Hedgehog
import Data.Eq.Deriving
(deriveEq1)
import Text.Show.Deriving
(deriveShow1)
import Data.Functor.Foldable
data AST f
= Addition f f
| Value Int
deriving stock (Functor, Eq, Show)
deriveShow1 ''AST
deriveEq1 ''AST
evaluate :: AST Int -> Int
evaluate = \case
Addition a b -> a + b
Value x -> x
render :: AST String -> String
render = \case
Addition a b -> a <> " + " <> b
Value x -> show x
parse :: [String] -> AST [String]
parse = \case
a : "+" : b : xs -> Addition (a : xs) [b]
[a] -> Value (read a)
_ -> Value 0
genAST :: Gen (Fix AST)
genAST = Gen.recursive Gen.choice
[ Fix . Value <$> Gen.integral (Range.linear 0 100) ]
[ Gen.subterm2 genAST genAST (\a b -> Fix (Addition a b))
]
prop_parse_render_tripping :: Property
prop_parse_render_tripping = property $ do
x <- forAll genAST
let rendered = cata render x
parsed = ana parse . words $ rendered
annotateShow rendered
annotateShow parsed
annotateShow $ cata evaluate x
cata evaluate parsed === cata evaluate x
prop_parse_render_hylo :: Property
prop_parse_render_hylo = property $ do
x <- forAll genAST
let rendered = cata render x
hylo evaluate parse (words rendered) === cata evaluate x
tests :: TestTree
tests = testGroup "Data.Functor.Foldable"
[ testProperty "cata and ana do reverse" $ prop_parse_render_tripping
, testProperty "hylo do reverse" $ prop_parse_render_hylo
]