mirror of
https://github.com/lexi-lambda/freer-simple.git
synced 2024-12-24 22:54:27 +03:00
43 lines
1.2 KiB
Haskell
43 lines
1.2 KiB
Haskell
{-# LANGUAGE FlexibleContexts #-}
|
|
module Tests.Reader (
|
|
testReader,
|
|
testMultiReader,
|
|
testLocal
|
|
) where
|
|
|
|
import Control.Monad.Freer
|
|
import Control.Monad.Freer.Reader
|
|
|
|
import Tests.Common
|
|
|
|
--------------------------------------------------------------------------------
|
|
-- Examples --
|
|
--------------------------------------------------------------------------------
|
|
testReader :: Int -> Int -> Int
|
|
testReader n x = run . flip runReader n $ ask `add` pure x
|
|
|
|
{-
|
|
t1rr' = run t1
|
|
No instance for (Member (Reader Int) Void)
|
|
arising from a use of `t1'
|
|
-}
|
|
|
|
testMultiReader :: Float -> Int -> Float
|
|
testMultiReader f n = run . flip runReader f . flip runReader n $ t2
|
|
where t2 = do
|
|
v1 <- ask
|
|
v2 <- ask
|
|
return $ fromIntegral (v1 + (1::Int)) + (v2 + (2::Float))
|
|
|
|
-- The opposite order of layers
|
|
{- If we mess up, we get an error
|
|
t2rrr1' = run $ runReader (runReader t2 (20::Float)) (10::Float)
|
|
No instance for (Member (Reader Int) [])
|
|
arising from a use of `t2'
|
|
-}
|
|
|
|
testLocal :: Int -> Int -> Int
|
|
testLocal env inc = run $ runReader t3 env
|
|
where t3 = t1 `add` local (+ inc) t1
|
|
t1 = ask `add` return (1 :: Int)
|