Add instances for Syntax and SyntaxChar.

Data/Syntax.hs

@@ -21,6 +21,7 @@ module Data.Syntax (
 
 import Prelude hiding (take, takeWhile)
 
+import Control.Category.Reader
 import Control.Lens.Iso
 import Control.Lens.SemiIso
 import Control.SIArrow
@@ -70,7 +71,7 @@ class ( SIArrow syn
     satisfyWith ai p = bifiltered p . ai /$/ anyChar
 
     -- | A specific string.
-    string :: (Seq syn) -> syn () ()
+    string :: Seq syn -> syn () ()
     string s = rev (exact s) /$/ take (olength s)
 
     -- | A string of length @n@.
@@ -94,3 +95,17 @@ class ( SIArrow syn
     takeTill1 p = takeWhile1 (not . p)
 
     {-# MINIMAL anyChar #-}
+
+instance Syntax syn => Syntax (ReaderCT env syn) where
+    type Seq (ReaderCT env syn) = Seq syn
+    anyChar = clift anyChar
+    char = clift . char
+    notChar = clift . notChar
+    satisfy = clift . satisfy
+    satisfyWith ai = clift . satisfyWith ai
+    string = clift . string
+    take = clift . take
+    takeWhile = clift . takeWhile
+    takeWhile1 = clift . takeWhile1
+    takeTill = clift . takeTill
+    takeTill1 = clift . takeTill1

Data/Syntax/Char.hs

@@ -25,6 +25,7 @@ module Data.Syntax.Char (
     digitHex
     ) where
 
+import Control.Category.Reader
 import Control.Lens.SemiIso
 import Control.SIArrow
 import Data.Bits
@@ -54,6 +55,12 @@ class (Syntax syn, Element (Seq syn) ~ Char) => SyntaxChar syn where
 
     {-# MINIMAL decimal, hexadecimal, realFloat, scientific #-}
 
+instance SyntaxChar syn => SyntaxChar (ReaderCT env syn) where
+    decimal = clift decimal
+    hexadecimal = clift hexadecimal
+    scientific = clift scientific
+    realFloat = clift realFloat
+
 -- | An useful synonym for SyntaxChars with Text sequences.
 type SyntaxText syn = (SyntaxChar syn, Seq syn ~ Text)
 

Data/Syntax/Indent.hs

@@ -34,25 +34,27 @@ newtype Indent cat a b = Indent { unIndent :: ReaderCT (Int, cat () ()) cat a b
 instance CategoryTrans Indent where
     clift = Indent . clift
 
+-- Generalized newtype deriving cannot derive this :(
+
 instance Syntax syn => Syntax (Indent syn) where
     type Seq (Indent syn) = Seq syn
-    anyChar = clift anyChar
-    char = clift . char
-    notChar = clift . notChar
-    satisfy = clift . satisfy
-    satisfyWith ai = clift . satisfyWith ai
-    string = clift . string
-    take = clift . take
-    takeWhile = clift . takeWhile
-    takeWhile1 = clift . takeWhile1
-    takeTill = clift . takeTill
-    takeTill1 = clift . takeTill1
+    anyChar = Indent anyChar
+    char = Indent . char
+    notChar = Indent . notChar
+    satisfy = Indent . satisfy
+    satisfyWith ai = Indent . satisfyWith ai
+    string = Indent . string
+    take = Indent . take
+    takeWhile = Indent . takeWhile
+    takeWhile1 = Indent . takeWhile1
+    takeTill = Indent . takeTill
+    takeTill1 = Indent . takeTill1
 
 instance SyntaxChar syn => SyntaxChar (Indent syn) where
-    decimal = clift decimal
-    hexadecimal = clift hexadecimal
-    scientific = clift scientific
-    realFloat = clift realFloat
+    decimal = Indent decimal
+    hexadecimal = Indent hexadecimal
+    scientific = Indent scientific
+    realFloat = Indent realFloat
 
 -- | @runIndent m tab@ runs the 'Indent' transformer using @tab@ once for each
 -- level of indentation.