auto-derive SortingCollection

[Lucu.git] / Data / Collections / Newtype / TH.hs

diff --git a/Data/Collections/Newtype/TH.hs b/Data/Collections/Newtype/TH.hs
index e3cb868e5ab460428cc7fbdce00427f00a7d0300..b3c7e59d41feb74a387e5939d59e0d6007a05ccf 100644 (file)
--- a/Data/Collections/Newtype/TH.hs
+++ b/Data/Collections/Newtype/TH.hs
@@ -8,6 +8,7 @@ module Data.Collections.Newtype.TH
     )
     where
 import Control.Applicative hiding (empty)
+import Control.Arrow
 import Control.Monad.Unicode
 import Data.Collections
 import Data.Collections.BaseInstances ()
@@ -56,6 +57,8 @@ inspectInstance (AppT (AppT (ConT classTy) wrapperTy) _)
         = return (wrapperTy, deriveFoldable)
     | classTy ≡ ''Collection
         = return (wrapperTy, deriveCollection)
+    | classTy ≡ ''SortingCollection
+        = return (wrapperTy, deriveSortingCollection)
 inspectInstance (AppT (AppT (AppT (ConT classTy) wrapperTy) _) _)
     | classTy ≡ ''Indexed
         = return (wrapperTy, deriveIndexed)
@@ -200,3 +203,15 @@ deriveIndexed c ty wrap unwrap
               = [| (($wrap ∘) ∘) ∘ (∘ $unwrap) ∘ accum |]
           | otherwise
               = fail $ "deriveIndexed: unknown method: " ⧺ pprint name
+
+deriveSortingCollection ∷ Q Cxt → Q Type → Q Exp → Q Exp → Q Dec
+deriveSortingCollection c ty wrap unwrap
+    = do names ← methodNames ''SortingCollection
+         instanceD c ty $ concatMap (pointfreeMethod exp) names
+    where
+      exp ∷ Name → Q Exp
+      exp name
+          | name ≡ 'minView
+              = [| (second $wrap <$>) ∘ minView ∘ $unwrap |]
+          | otherwise
+              = fail $ "deriveSortingCollection: unknown method: " ⧺ pprint name