Add an importModule function.

This function allows us to import a module inside the TcRn monad and
properly handles (family) instances. This is needed for working with the
tfp package.

diff --git a/HsTools.hs b/HsTools.hs
index ae5582a002f1c2f2d8d3685d5cfafe1216d369c1..a058c84e1e065468d7065349ec1091457407e426 100644 (file)
--- a/HsTools.hs
+++ b/HsTools.hs
@@ -14,6 +14,7 @@ import qualified FastString
 import qualified StringBuffer
 import qualified MonadUtils
 import Outputable ( showSDoc, ppr )
 import qualified StringBuffer
 import qualified MonadUtils
 import Outputable ( showSDoc, ppr )

+import qualified Outputable

 -- Lexer & Parser, i.e. up to HsExpr
 import qualified Lexer
 import qualified Parser
 -- Lexer & Parser, i.e. up to HsExpr
 import qualified Lexer
 import qualified Parser


@@ -24,19 +25,25 @@ import qualified HsExpr
 import qualified HsTypes
 import qualified HsBinds
 import qualified TcRnMonad
 import qualified HsTypes
 import qualified HsBinds
 import qualified TcRnMonad

+import qualified TcRnTypes

 import qualified RnExpr
 import qualified RnEnv
 import qualified TcExpr
 import qualified TcEnv
 import qualified TcSimplify
 import qualified Desugar
 import qualified RnExpr
 import qualified RnEnv
 import qualified TcExpr
 import qualified TcEnv
 import qualified TcSimplify
 import qualified Desugar

+import qualified InstEnv
+import qualified FamInstEnv

 import qualified PrelNames
 import qualified Module
 import qualified OccName
 import qualified RdrName
 import qualified Name
 import qualified PrelNames
 import qualified Module
 import qualified OccName
 import qualified RdrName
 import qualified Name

+import qualified TysWiredIn

 import qualified SrcLoc
 import qualified SrcLoc

+import qualified LoadIface

 import qualified BasicTypes
 import qualified BasicTypes

+import qualified Bag

 -- Core representation and handling
 import qualified CoreSyn
 import qualified Id
 -- Core representation and handling
 import qualified CoreSyn
 import qualified Id


@@ -185,3 +192,30 @@ hscParseThing parser dflags str = do
     let Lexer.POk _ thing = Lexer.unP parser (Lexer.mkPState buf loc dflags)
     return thing
 
     let Lexer.POk _ thing = Lexer.unP parser (Lexer.mkPState buf loc dflags)
     return thing
 

+-- | This function imports the module with the given name, for the renamer /
+-- typechecker to use. It also imports any "orphans" and "family instances"
+-- from modules included by this module, but not the actual modules
+-- themselves. I'm not 100% sure how this works, but it seems that any
+-- functions defined in included modules are available just by loading the
+-- original module, and by doing this orphan stuff, any (type family or class)
+-- instances are available as well.
+--
+-- Most of the code is based on tcRnImports and rnImportDecl, but those
+-- functions do a lot more (which I hope we won't need...).
+importModule :: Module.ModuleName -> TcRnTypes.RnM ()
+importModule mod = do
+  let reason = Outputable.text "Hardcoded import" -- Used for trace output
+  let pkg = Nothing
+  -- Load the interface.
+  iface <- LoadIface.loadSrcInterface reason mod False pkg
+  -- Load orphan an familiy instance dependencies as well. I think these
+  -- dependencies are needed for the type checker to know all instances. Any
+  -- other instances (on other packages) are only useful to the
+  -- linker, so we can probably safely ignore them here. Dependencies within
+  -- the same package are also listed in deps, but I'm not so sure what to do
+  -- with them.
+  let deps = HscTypes.mi_deps iface
+  let orphs = HscTypes.dep_orphs deps
+  let finsts = HscTypes.dep_finsts deps
+  LoadIface.loadOrphanModules orphs False
+  LoadIface.loadOrphanModules finsts True