derive-2.0.1: A program and library to derive instances for data types Source code Contents Index

Data.Derive.Internal.Traversal

Description

Derives Functor and similair classes, as discussed on the Haskell-prime mailing list: http://www.mail-archive.com/haskell-prime@haskell.org/msg02116.html.

Synopsis

data TraveralType = TraveralType { traversalArg :: Int traversalCo :: Bool traversalName :: QName traversalId :: Trav traversalDirect :: Trav traversalFunc :: QName -> Trav -> Trav traversalPlus :: Trav -> Trav -> Trav traverseArrow :: Maybe (Trav -> Trav -> Trav) traverseTuple :: [Exp] -> Exp traverseCtor :: String -> [Exp] -> Exp traverseFunc :: Pat -> Exp -> Match } defaultTraversalType traversalDerivation1 :: TraveralType -> String -> Derivation traversalInstance :: TraveralType -> String -> DataDecl -> [WithInstances Decl] -> [Decl] traversalInstance1 :: TraveralType -> String -> FullDataDecl -> Either String [Decl] deriveTraversal :: TraveralType -> DataDecl -> WithInstances Decl

Documentation

data TraveralType Source

What kind of traversal are we deriving? Constructors TraveralType traversalArg :: Int On what position are we traversing? traversalCo :: Bool covariant? traversalName :: QName name of the traversal function traversalId :: Trav Identity traversal traversalDirect :: Trav Traversal of a traversalFunc :: QName -> Trav -> Trav Apply the sub-traversal function traversalPlus :: Trav -> Trav -> Trav Apply two non-identity traversals in sequence traverseArrow :: Maybe (Trav -> Trav -> Trav) Traverse a function type traverseTuple :: [Exp] -> Exp Construct a tuple from applied traversals traverseCtor :: String -> [Exp] -> Exp Construct a data type from applied traversals traverseFunc :: Pat -> Exp -> Match Construct a clause of the traversal function

defaultTraversalType

traversalDerivation1 :: TraveralType -> String -> Derivation Source

Derivation for a Traversable like class with just 1 method

traversalInstance :: TraveralType -> String -> DataDecl -> [WithInstances Decl] -> [Decl] Source

Instance for a Traversable like class

traversalInstance1 :: TraveralType -> String -> FullDataDecl -> Either String [Decl] Source

Instance for a Traversable like class with just 1 method

deriveTraversal :: TraveralType -> DataDecl -> WithInstances Decl Source

Derive a traverse like function

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