hsSyn/HsSyn.hs

    {-
    (c) The University of Glasgow 2006
    (c) The GRASP/AQUA Project, Glasgow University, 1992-1998

    \section{Haskell abstract syntax definition}

    This module glues together the pieces of the Haskell abstract syntax,
    which is declared in the various \tr{Hs*} modules.  This module,
    therefore, is almost nothing but re-exporting.
    -}

    {-# LANGUAGE DeriveDataTypeable #-}
    {-# LANGUAGE StandaloneDeriving #-}
    {-# LANGUAGE FlexibleContexts #-}
    {-# LANGUAGE UndecidableInstances #-} -- Note [Pass sensitive types]
                                          -- in module PlaceHolder
    {-# LANGUAGE ConstraintKinds #-}

    module HsSyn (
            module HsBinds,
            module HsDecls,
            module HsExpr,
            module HsImpExp,
            module HsLit,
            module HsPat,
            module HsTypes,
            module HsUtils,
            module HsDoc,
            module PlaceHolder,
            Fixity,

            HsModule(..)
    ) where

    -- friends:
    import HsDecls
    import HsBinds
    import HsExpr
    import HsImpExp
    import HsLit
    import PlaceHolder
    import HsPat
    import HsTypes
    import BasicTypes       ( Fixity, WarningTxt )
    import HsUtils
    import HsDoc
    import OccName          ( HasOccName(..) )

    -- others:
    import Outputable
    import SrcLoc
    import Module           ( ModuleName )

    -- libraries:
    import Data.Data hiding ( Fixity )

    -- | Haskell Module
    --
    -- All we actually declare here is the top-level structure for a module.
    data HsModule name
      = HsModule {
          hsmodName :: Maybe (Located ModuleName),
            -- ^ @Nothing@: \"module X where\" is omitted (in which case the next
            --     field is Nothing too)
          hsmodExports :: Maybe (Located [LIE name]),
            -- ^ Export list
            --
            --  - @Nothing@: export list omitted, so export everything
            --
            --  - @Just []@: export /nothing/
            --
            --  - @Just [...]@: as you would expect...
            --
            --
            --  - 'ApiAnnotation.AnnKeywordId's : 'ApiAnnotation.AnnOpen'
            --                                   ,'ApiAnnotation.AnnClose'

            -- For details on above see note [Api annotations] in ApiAnnotation
          hsmodImports :: [LImportDecl name],
            -- ^ We snaffle interesting stuff out of the imported interfaces early
            -- on, adding that info to TyDecls/etc; so this list is often empty,
            -- downstream.
          hsmodDecls :: [LHsDecl name],
            -- ^ Type, class, value, and interface signature decls
          hsmodDeprecMessage :: Maybe (Located WarningTxt),
            -- ^ reason\/explanation for warning/deprecation of this module
            --
            --  - 'ApiAnnotation.AnnKeywordId's : 'ApiAnnotation.AnnOpen'
            --                                   ,'ApiAnnotation.AnnClose'
            --

            -- For details on above see note [Api annotations] in ApiAnnotation
          hsmodHaddockModHeader :: Maybe LHsDocString
            -- ^ Haddock module info and description, unparsed
            --
            --  - 'ApiAnnotation.AnnKeywordId's : 'ApiAnnotation.AnnOpen'
            --                                   ,'ApiAnnotation.AnnClose'

            -- For details on above see note [Api annotations] in ApiAnnotation
       }
         -- ^ 'ApiAnnotation.AnnKeywordId's
         --
         --  - 'ApiAnnotation.AnnModule','ApiAnnotation.AnnWhere'
         --
         --  - 'ApiAnnotation.AnnOpen','ApiAnnotation.AnnSemi',
         --    'ApiAnnotation.AnnClose' for explicit braces and semi around
         --    hsmodImports,hsmodDecls if this style is used.

         -- For details on above see note [Api annotations] in ApiAnnotation
    deriving instance (DataId name) => Data (HsModule name)

    instance (OutputableBndrId name, HasOccName name)
      => Outputable (HsModule name) where

        ppr (HsModule Nothing _ imports decls _ mbDoc)
          = pp_mb mbDoc $$ pp_nonnull imports
                        $$ pp_nonnull decls

        ppr (HsModule (Just name) exports imports decls deprec mbDoc)
          = vcat [
                pp_mb mbDoc,
                case exports of
                  Nothing -> pp_header (text "where")
                  Just es -> vcat [
                               pp_header lparen,
                               nest 8 (fsep (punctuate comma (map ppr (unLoc es)))),
                               nest 4 (text ") where")
                              ],
                pp_nonnull imports,
                pp_nonnull decls
              ]
          where
            pp_header rest = case deprec of
               Nothing -> pp_modname <+> rest
               Just d -> vcat [ pp_modname, ppr d, rest ]

            pp_modname = text "module" <+> ppr name

    pp_mb :: Outputable t => Maybe t -> SDoc
    pp_mb (Just x) = ppr x
    pp_mb Nothing  = empty

    pp_nonnull :: Outputable t => [t] -> SDoc
    pp_nonnull [] = empty
    pp_nonnull xs = vcat (map ppr xs)