diff --git a/src/compiler/GF.hs b/src/compiler/GF.hs
index bdb3e9b48..64c3184c6 100644
--- a/src/compiler/GF.hs
+++ b/src/compiler/GF.hs
@@ -1,8 +1,8 @@
 module GF(
            -- * Command line interface
            module GF.Main,
-           module GF.Compiler,
            module GF.Interactive,
+           module GF.Compiler,
 
            -- * Compiling GF grammars
            module GF.Compile,
@@ -11,7 +11,10 @@ module GF(
 
            -- * Abstract syntax, parsing and pretty printing
            module GF.Compile.GetGrammar,
-           module GF.Grammar,
+           module GF.Grammar.Grammar,
+           module GF.Grammar.Macros,
+           module GF.Grammar.Printer,
+           module GF.Infra.Ident,
 
            -- * Supporting infrastructure and system utilities
            module GF.Data.Operations,
@@ -28,7 +31,10 @@ import GF.CompileInParallel
 import GF.CompileOne
 
 import GF.Compile.GetGrammar
-import GF.Grammar
+import GF.Grammar.Grammar
+import GF.Grammar.Macros
+import GF.Grammar.Printer
+import GF.Infra.Ident
 
 import GF.Data.Operations
 import GF.Infra.Option
diff --git a/src/compiler/GF/Compile.hs b/src/compiler/GF/Compile.hs
index b52469cdb..fb37cd1fe 100644
--- a/src/compiler/GF/Compile.hs
+++ b/src/compiler/GF/Compile.hs
@@ -26,6 +26,7 @@ import PGF.Internal(optimizePGF)
 import PGF(PGF,defaultProbabilities,setProbabilities,readProbabilitiesFromFile)
 
 -- | Compiles a number of source files and builds a 'PGF' structure for them.
+-- This is a composition of 'batchCompile' and 'link'.
 compileToPGF :: Options -> [FilePath] -> IOE PGF
 compileToPGF opts fs = link opts =<< batchCompile opts fs
 
diff --git a/src/compiler/GF/Compile/Compute/ConcreteNew.hs b/src/compiler/GF/Compile/Compute/ConcreteNew.hs
index c4793c023..6bc653983 100644
--- a/src/compiler/GF/Compile/Compute/ConcreteNew.hs
+++ b/src/compiler/GF/Compile/Compute/ConcreteNew.hs
@@ -7,7 +7,7 @@ module GF.Compile.Compute.ConcreteNew
 
 import GF.Grammar hiding (Env, VGen, VApp, VRecType)
 import GF.Grammar.Lookup(lookupResDefLoc,allParamValues)
-import GF.Grammar.Predef(cPredef,cErrorType,cTok,cStr)
+import GF.Grammar.Predef(cPredef,cErrorType,cTok,cStr,isPredefCat)
 import GF.Grammar.PatternMatch(matchPattern,measurePatt)
 import GF.Grammar.Lockfield(lockLabel,isLockLabel,lockRecType) --unlockRecord
 import GF.Compile.Compute.Value hiding (Error)
diff --git a/src/compiler/GF/Compiler.hs b/src/compiler/GF/Compiler.hs
index 407ef4e64..e607c7acc 100644
--- a/src/compiler/GF/Compiler.hs
+++ b/src/compiler/GF/Compiler.hs
@@ -1,4 +1,4 @@
-module GF.Compiler (mainGFC, writePGF) where
+module GF.Compiler (mainGFC, writePGF, linkGrammars) where
 
 import PGF
 import PGF.Internal(concretes,optimizePGF,unionPGF)
@@ -23,6 +23,8 @@ import qualified Data.ByteString.Lazy as BSL
 import System.FilePath
 import Control.Monad(unless,forM_)
 
+-- | Compile the given GF grammar files. The result is a number of @.gfo@ files
+-- and, depending on the options, a @.pgf@ file. (@gf -batch@, @gf -make@)
 mainGFC :: Options -> [FilePath] -> IO ()
 mainGFC opts fs = do
   r <- appIOE (case () of
@@ -41,25 +43,29 @@ mainGFC opts fs = do
 
 compileSourceFiles :: Options -> [FilePath] -> IOE ()
 compileSourceFiles opts fs = 
-    do (t_src,~cnc_grs@(~(cnc,gr):_)) <- batchCompile opts fs
+    do output <- batchCompile opts fs
        unless (flag optStopAfterPhase opts == Compile) $
-              do let abs = showIdent (srcAbsName gr cnc)
-                     pgfFile = outputPath opts (grammarName' opts abs<.>"pgf")
-                 t_pgf <- if outputJustPGF opts
-                          then maybeIO $ getModificationTime pgfFile
-                          else return Nothing
-                 if t_pgf >= Just t_src
-                   then putIfVerb opts $ pgfFile ++ " is up-to-date."
-                   else do pgfs <- mapM (link opts)
-                                        [(cnc,t_src,gr)|(cnc,gr)<-cnc_grs]
-                           let pgf = foldl1 unionPGF pgfs
-                           writePGF opts pgf
-                           writeOutputs opts pgf
+           linkGrammars opts output
   where
     batchCompile = maybe batchCompile' parallelBatchCompile (flag optJobs opts)
     batchCompile' opts fs = do (cnc,t,gr) <- S.batchCompile opts fs
                                return (t,[(cnc,gr)])
 
+-- | Create a @.pgf@ file from the output of 'parallelBatchCompile'.
+linkGrammars opts (t_src,~cnc_grs@(~(cnc,gr):_)) =
+    do let abs = showIdent (srcAbsName gr cnc)
+           pgfFile = outputPath opts (grammarName' opts abs<.>"pgf")
+       t_pgf <- if outputJustPGF opts
+                then maybeIO $ getModificationTime pgfFile
+                else return Nothing
+       if t_pgf >= Just t_src
+         then putIfVerb opts $ pgfFile ++ " is up-to-date."
+         else do pgfs <- mapM (link opts)
+                              [(cnc,t_src,gr)|(cnc,gr)<-cnc_grs]
+                 let pgf = foldl1 unionPGF pgfs
+                 writePGF opts pgf
+                 writeOutputs opts pgf
+
 compileCFFiles :: Options -> [FilePath] -> IOE ()
 compileCFFiles opts fs = do
   rules <- fmap concat $ mapM (getCFRules opts) fs
@@ -107,6 +113,9 @@ writeOutputs opts pgf = do
                  | fmt <- outputFormats opts,
                    (name,str) <- exportPGF opts fmt pgf]
 
+-- | Write the result of compiling a grammar (e.g. with 'compileToPGF' or
+-- 'link') to a @.pgf@ file.
+-- A split PGF file is output if the @-split-pgf@ option is used.
 writePGF :: Options -> PGF -> IOE ()
 writePGF opts pgf =
     if flag optSplitPGF opts then writeSplitPGF else writeNormalPGF
diff --git a/src/compiler/GF/Interactive.hs b/src/compiler/GF/Interactive.hs
index 5944d04a7..18bee2e49 100644
--- a/src/compiler/GF/Interactive.hs
+++ b/src/compiler/GF/Interactive.hs
@@ -53,7 +53,7 @@ import GF.Infra.BuildInfo(buildInfo)
 import Data.Version(showVersion)
 import Paths_gf(version)
 
--- | Run the GF Shell in quiet mode
+-- | Run the GF Shell in quiet mode (@gf -run@).
 mainRunGFI :: Options -> [FilePath] -> IO ()
 mainRunGFI opts files = shell (beQuiet opts) files
 
@@ -68,7 +68,8 @@ mainGFI opts files = do
 shell opts files = loop opts =<< runSIO (importInEnv emptyGFEnv opts files)
 
 #ifdef SERVER_MODE
--- | Start GF Server
+-- | Run the GF Server (@gf -server@).
+-- The 'Int' argument is the port number for the HTTP service.
 mainServerGFI opts0 port files =
     server port root (execute1 opts)
       =<< runSIO (importInEnv emptyGFEnv opts files)