Language.Haskell.TH.Lib.Extra

This module provides extra helper functions complementing Language.Haskell.TH.Lib

Extra template functions

Extra functions to generate haskell templates.

integralE :: Integral a => a -> ExpQ

Integer literal template from Integral types.

simpleValD :: Name -> TypeQ -> ExpQ -> Q [Dec]

Generate declaration template from name, type and expression.

maybeD :: (a -> Q [Dec]) -> Maybe a -> Q [Dec]

May generate declaration template.

Pretty printing for Q monad

Pretty printing for haskell templates.

pprQ :: (Functor m, Quasi m, Ppr a) => Q a -> m Doc

Helper function for pretty printing Q Monad.

Functions to print message or errors when compile time

Functions to display or to raise compile messages from codes which generating haskell templates.

Only messages directly generated by Q monad report actions are handled by ghc loggers.

-- Handled by ghc logger
qReport False "Foo"

-- Not handled by ghc logger
runIO . runQ $ qReport False "Foo"

reportMessage :: Quasi m => String -> m ()

Print compile message from TH code. Only display when TH_EXTRA_MESSAGE_OUTPUT environment variable is set. When variable value string is as_warn or as_warning and using Q monad action, Output is put into ghc logger as warning. Other cases are normal standard error output.

reportWarning :: String -> Q ()

Print compile warnings from TH code.

reportError :: String -> Q ()

Print compile errors from TH code.