fix: GHC 7.8 and 7.10 compatibility

changelog.md

@@ -1,3 +1,7 @@
+# 0.2.4.1 (November 25, 2016)
+
+* Restore GHC (7.8, 7.10) compatibility
+
 # 0.2.4.0 (November 25, 2016)
 
 * Internal reorg

examples/src/Teletype.hs

@@ -2,11 +2,16 @@
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE CPP #-}
 module Teletype where
 
-import Control.Monad.Freer
+#if __GLASGOW_HASKELL__ < 710
+import Control.Applicative (pure)
+#endif
 import System.Exit hiding (ExitSuccess)
 
+import Control.Monad.Freer
+
 --------------------------------------------------------------------------------
                           -- Effect Model --
 --------------------------------------------------------------------------------
@@ -42,11 +47,10 @@ runTeletypePure :: [String] -> Eff '[Teletype] w -> [String]
 runTeletypePure inputs req =
   reverse . snd $ run (handleRelayS (inputs, []) (\s _ -> pure s) go req)
   where
-    go
+    go :: ([String], [String])
-      :: ([String], [String])
+       -> Teletype v
-      -> Teletype v
+       -> (([String], [String]) -> Arr '[] v ([String], [String]))
-      -> (([String], [String]) -> Arr '[] v ([String], [String]))
+       -> Eff '[] ([String], [String])
-      -> Eff '[] ([String], [String])
     go (is, os) (PutStrLn msg) q = q (is, msg : os) ()
     go (i:is, os) GetLine q = q (is, os) i
     go ([], _) GetLine _ = error "Not enough lines"

freer.cabal

@@ -1,5 +1,5 @@
 name:                freer
-version:             0.2.4.0
+version:             0.2.4.1
 synopsis:            Implementation of the Freer Monad
 license:             BSD3
 license-file:        LICENSE
@@ -10,8 +10,8 @@ homepage:            https://gitlab.com/queertypes/freer
 bug-reports:         https://gitlab.com/queertypes/freer/issues
 category:            Control
 build-type:          Simple
-cabal-version:       >=1.18
+cabal-version:       >=1.10
-tested-with:         GHC==7.10.2
+tested-with:         GHC==7.10.3, GHC==8.0.1, GHC==7.8.4
 description:
 
     Freer is an implementation of "Freer Monads, More Extensible
@@ -64,7 +64,7 @@ executable freer-examples
                      , NonDetEff
                      , Teletype
                      , Trace
-  build-depends:       base >=4.7 && <5
+  build-depends:       base
                      , freer
   hs-source-dirs:      examples/src
   ghc-options:         -Wall

src/Control/Monad/Freer.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE CPP #-}
 {-|
 Module      : Control.Monad.Freer
 Description : Freer - an extensible effects library
@@ -28,6 +29,10 @@ module Control.Monad.Freer (
   msplit
 ) where
 
+#if __GLASGOW_HASKELL__ < 710
+import Control.Applicative (pure)
+#endif
+
 import Control.Monad.Freer.Internal
 
 runNat

src/Data/Open/Union/Internal.hs

@@ -25,7 +25,7 @@ instance (r ~ (t ': r')) => Member' t r 'Z where
   prj' _ (UNow x) = Just x
   prj' _ _        = Nothing
 
-instance (r ~ (t' ': r' : rs'), Member' t (r' : rs') n) => Member' t r ('S n) where
+instance (r ~ (t' ': r' ': rs'), Member' t (r' ': rs') n) => Member' t r ('S n) where
   inj' _ = UNext . inj' (P::P n)
   prj' _ (UNow _)  = Nothing
   prj' _ (UNext x) = prj' (P::P n) x
@@ -73,5 +73,3 @@ instance (Functor f) => Functor (Union '[f]) where
 instance (Functor f1, Functor (Union (f2 ': fs))) =>
          Functor (Union (f1 ': f2 ': fs)) where
   fmap f = either (weaken . fmap f) (inj . fmap f) . decomp
-
-