yoko 0.3.1.3 → 0.3.2
raw patch · 2 files changed
+45/−18 lines, 2 filesdep +invariant
Dependencies added: invariant
Files
- Data/Yoko/TH.hs +37/−16
- yoko.cabal +8/−2
Data/Yoko/TH.hs view
@@ -13,23 +13,41 @@ This bundled Template Haskell derives all fields types and @yoko@ instances for users' data types. -'yokoTH' is the prinicpal deriver, but it can be customized via 'yokoTH_with',-which lets the user specify how to represent composite fields that include-applications of type with higher-kinds than @*->*@.+'yokoTH' is the prinicpal deriver, but it can be customized in two ways via+'yokoTH_with'. First, the user can specify how to derive the names of fields+types from the original constructor name -- the default is @(++ \"_\")@.+Second, the user can specify how to represent composite fields that include+applications of types with higher-kinds. This is done by providing a 'Mapping'. -For instance, @yokoTH@ cannot handle @data T = C0 | C1 [(Int, T T)]@.+Each 'Mapping' specifies a representation type, its constructor, and a+structure-preserving mapping function. The default options handle applications+of @*->*@ and @*->*->*@ types with the 'Par1' and 'Par2' types from+"Data.Yoko.Representation" and uses the 'invmap' and 'invmap2' mapping+functions from the @invariant@ package. -The following invocation of @yokoTH_with@ does. @Par2@ is declared in-"Data.Yoko.Representation", but @Bifunctor@ is not.+For example, @yokoTH@ cannot handle @data T = C0 | C1 (T, T, T)@, since '(,,)'+is applied at kind @*->*->*@. It can, however handle @data U = C0 | C1 (Int, U,+U)@, since @(,,) Int@ is applied at kind @*->*->*@ -- the kind of the+application is determined by the leftmost argument with a recursive+occurrence. In this case, @yokoTH@ uses the default @Mapping ''Par2 'Par2+'invmap2@. +The following invocation of @yokoTH_with@ can handle @T@, since it provides an+additional mapping to be used with 3-argument applications.+ @-class Bifunctor f where- bifmap :: (a -> c) -> (b -> d) -> f a b -> f c d+class Invariant3 f where+ invmap3 :: (a -> x) -> (x -> a) ->+ (b -> y) -> (y -> b) ->+ (c -> z) -> (z -> c) ->+ f a b c -> f x y z -instance Bifunctor ((,,) a) where- bifmap f g ~(a, x, y) = (a, f x, g y)+instance Invariant3 (,,) where+ invmap3 f _ g _ h _ ~(x, y, z) = (f x, g y, h z) -yokoTH_with (yokoDefaults {mappings = ((2, Mapping ''Par2 'Par2 'bifmap) :)}) ''T+newtype Par3 f a b c = Par3 (f a b c)++yokoTH_with (yokoDefaults {mappings = ((3, Mapping ''Par3 'Par3 'invmap3) :)}) ''T @ As always, use @{- OPTIONS_GHC -ddump-splices -}@ to inspect the generated@@ -58,6 +76,8 @@ import qualified Data.Yoko.TH.Internal as Int +import Data.Functor.Invariant (invmap, invmap2)+ import qualified Control.Monad.Writer as Writer import qualified Control.Monad.Trans as Trans @@ -99,7 +119,7 @@ -- | A 'Mapping' identifies the representation type, its constructor, and the -- associated mapping function. For example, 'Par1' is represented with--- @Mapping ''Par1 'Par1 'fmap@.+-- @Mapping ''Par1 'Par1 'invmap@. data Mapping = Mapping {containerTypeName :: Name, containerCtor :: Name, methodName :: Name}@@ -110,7 +130,7 @@ -- @(++ \"_\")@. renamer :: (String -> String) -> (String -> String), -- | How applications of higher-rank data types are represented. Defaults- -- to @[(1, 'Mapping' ''Par1 'Par1 'fmap)]@.+ -- to @[(1, 'Mapping' ''Par1 'Par1 'invmap), (2, 'Mapping' ''Par2 'Par2 'invmap2)]@. mappings :: [(Int, Mapping)] -> [(Int, Mapping)]} -- | The default options. @yokoDefaults = YokoOptions id id@.@@ -138,7 +158,8 @@ yokoTH_with :: YokoOptions -> Name -> Q [Dec] yokoTH_with options n = runM $ yoko0 $ X :& Target := n :& Renamer := (mkName . renamer options (++ "_") . TH.nameBase)- :& Mappings := mappings options [(1, Mapping ''Par1 'Par1 'fmap)]+ :& Mappings := mappings options [(1, Mapping ''Par1 'Par1 'invmap),+ (2, Mapping ''Par2 'Par2 'invmap2)] @@ -244,8 +265,8 @@ recs <- mapM w' recs let snoc (tyL, fROL) (tyR, fROR) = (tyL `AppT` tyR, fROL `appRO` fROR)- appRO l r = FieldRO {repF = repF l `AppE` repF r,- objF = objF l `AppE` objF r}+ appRO l r = FieldRO {repF = repF l `AppE` repF r `AppE` objF r,+ objF = objF l `AppE` objF r `AppE` repF r} post fRO = FieldRO {repF = ConE ctor `compose` repF fRO, objF = objF fRO `compose` dtor} return $ Arrow.second post $ foldl snoc
yoko.cabal view
@@ -1,5 +1,5 @@ name: yoko-version: 0.3.1.3+version: 0.3.2 synopsis: Generic Programming with Disbanded Data Types description:@@ -79,12 +79,19 @@ extra-source-files: README, CHANGES, Examples/*.hs, Examples/LambdaLift/*.hs +source-repository head+ type: git+ location: git://github.com/nfrisby/yoko.git + library build-depends: base >= 4 && < 5, template-haskell > 2.7 && < 2.8, containers >= 0.4 && < 0.5, mtl >= 2.0 && < 2.1++ build-depends: th-sccs < 0.1, invariant < 0.2+ build-depends: type-equality < 0.2 build-depends:@@ -93,7 +100,6 @@ records >= 0.1.1.6 && < 0.2 build-depends:- th-sccs < 0.1, type-booleans < 0.2, type-spine >= 0.1.1 && < 0.2, tagged-th < 0.2,