Language.Haskell.TH.TypeGraph.Stack

The HasStack monad used in MIMO to construct lenses that look deep into a record type. However, it does not involve the Path type mechanism, and is unaware of View instances and other things that modify the type graph. Lets see how it adapts.

Documentation

data TypeStack

A stack describes a path from a top type down through fields of its component types.

Constructors

TypeStack

Fields

_topType :: Type

_typeStack :: [StackElement]

Instances

Eq TypeStack

Data TypeStack

Show TypeStack

MonadReaders TypeInfo m => MonadReaders TypeInfo (ReaderT TypeStack m)

topType :: Lens' TypeStack Type

typeStack :: Lens' TypeStack [StackElement]

data StackElement

The information required to extact a field value from a value. We keep a stack of these as we traverse a declaration. Generally, we only need the field names.

Constructors

StackElement FieldType Con Dec

Instances

Eq StackElement

Data StackElement

Show StackElement

(Monad m, MonadReaders [StackElement] m) => MonadReaders [StackElement] (ReaderT TypeGraph m)

prettyStack :: TypeStack -> String

foldField :: MonadReaders TypeStack m => (FieldType -> m r) -> Dec -> Con -> FieldType -> m r

Push the stack and process the field.

Stack+instance map monad

type HasStack = MonadReaders TypeStack

type StackT m = ReaderT TypeStack m

execStackT :: Monad m => StackT m a -> Type -> m a

withStack :: (Monad m, MonadReaders TypeStack m) => (TypeStack -> m a) -> m a

push :: MonadReaders TypeStack m => FieldType -> Con -> Dec -> m a -> m a

push an element onto the TypeStack in m

Stack operations

stackAccessor :: (Quasi m, MonadReaders TypeStack m) => m Exp

Return a lambda function that turns a value of Type typ0 into the type implied by the stack elements.

traceIndented :: MonadReaders TypeStack m => String -> m ()

lensNamer :: String -> String

Given a field name, return the name to use for the corresponding lens.