X-Git-Url: https://git.cielonegro.org/gitweb.cgi?a=blobdiff_plain;f=Data%2FCollections%2FNewtype%2FTH.hs;h=0301fd37562222cc896bc9246dc20c0c423d1bba;hb=8de439e0d2869f46e926d3132f6b1113201460e5;hp=d392758a4be3c3eaaaaa690037b2fdbef8b6aa97;hpb=b2da45926a7900603a5426e0c6d65e3ca630a1a2;p=Lucu.git

diff --git a/Data/Collections/Newtype/TH.hs b/Data/Collections/Newtype/TH.hs
index d392758..0301fd3 100644
--- a/Data/Collections/Newtype/TH.hs
+++ b/Data/Collections/Newtype/TH.hs
@@ -2,7 +2,9 @@
     TemplateHaskell
   , UnicodeSyntax
   #-}
--- |FIXME: doc
+-- |Doesn't anyone know why these instances can't be derived using
+-- GeneralizedNewtypeDeriving? I think its limitation isn't reasonable
+-- at all...
 module Data.Collections.Newtype.TH
     ( derive
     )
@@ -27,7 +29,42 @@ import Prelude.Unicode
 
 type Deriver = Q Cxt → Q Type → Q Exp → Q Exp → Q Dec
 
--- |FIXME: doc
+-- |Automatic newtype instance deriver for type classes defined by the
+-- collections-api package.
+--
+-- @
+--   {-\# LANGUAGE TemplateHaskell \#-}
+--   module Foo (T) where
+--   import "Data.Collections"
+--   import "Data.Collections.BaseInstances" ()
+--   import qualified Data.Collections.Newtype.TH as C
+--   import qualified "Data.Map" as M
+--
+--   newtype T = T (M.Map 'Int' 'Bool')
+--
+--   C.derive [d| instance 'Unfoldable' T ('Int', 'Bool')
+--                instance 'Foldable'   T ('Int', 'Bool')
+--                instance 'Indexed'    T  'Int'  'Bool'
+--                ...
+--              |]
+-- @
+--
+-- This function can derive the following instances:
+--
+--   * 'Unfoldable'
+--
+--   * 'Foldable'
+--
+--   * 'Collection'
+--
+--   * 'Indexed'
+--
+--   * 'Map'
+--
+--   * 'Set'
+--
+--   * 'SortingCollection'
+--
 derive ∷ Q [Dec] → Q [Dec]
 derive = (concat <$>) ∘ (mapM go =≪)
     where
@@ -59,6 +96,8 @@ inspectInstance (AppT (AppT (ConT classTy) wrapperTy) _)
         = return (wrapperTy, deriveFoldable)
     | classTy ≡ ''Collection
         = return (wrapperTy, deriveCollection)
+    | classTy ≡ ''Set
+        = return (wrapperTy, deriveSet)
     | classTy ≡ ''SortingCollection
         = return (wrapperTy, deriveSortingCollection)
 inspectInstance (AppT (AppT (AppT (ConT classTy) wrapperTy) _) _)
@@ -254,6 +293,18 @@ deriveMap c ty wrap unwrap
           | otherwise
               = fail $ "deriveMap: unknown method: " ⧺ pprint name
 
+deriveSet ∷ Q Cxt → Q Type → Q Exp → Q Exp → Q Dec
+deriveSet c ty _ _
+    = do names ← methodNames ''Set
+         instanceD c ty $ concatMap (pointfreeMethod exp) names
+    where
+      exp ∷ Name → Q Exp
+      exp name
+          | name ≡ 'haddock_candy
+              = [| haddock_candy |]
+          | otherwise
+              = fail $ "deriveSet: unknown method: " ⧺ pprint name
+
 deriveSortingCollection ∷ Q Cxt → Q Type → Q Exp → Q Exp → Q Dec
 deriveSortingCollection c ty wrap unwrap
     = do names ← methodNames ''SortingCollection