PGF.hs: export function missingLins

Also in Commands.hs: be explicit about things imported from the PGF library
that are not in the public API.
Also a couple of haddock documentation fixes.

src/runtime/haskell/PGF.hs

@@ -35,7 +35,7 @@ module PGF(
            categories, startCat,
 
            -- * Functions
-           functions, functionsByCat, functionType,
+           functions, functionsByCat, functionType, missingLins,
 
            -- * Expressions & Trees
            -- ** Tree
@@ -132,7 +132,7 @@ module PGF(
            showProbabilities,
            readProbabilitiesFromFile,
            
-           -- ** SortTop
+           -- -- ** SortTop
 --         forExample,
 
            -- * Browsing

src/runtime/haskell/PGF/Macros.hs

@@ -69,12 +69,13 @@ functionsToCat pgf cat =
  where 
    (_,fs,_) = lookMap ([],[],0) cat $ cats $ abstract pgf
 
-missingLins :: PGF -> CId -> [CId]
+-- | List of functions that lack linearizations in the given language.
+missingLins :: PGF -> Language -> [CId]
 missingLins pgf lang = [c | c <- fs, not (hasl c)] where
   fs = Map.keys $ funs $ abstract pgf
   hasl = hasLin pgf lang
 
-hasLin :: PGF -> CId -> CId -> Bool
+hasLin :: PGF -> Language -> CId -> Bool
 hasLin pgf lang f = Map.member f $ lproductions $ lookConcr pgf lang
 
 restrictPGF :: (CId -> Bool) -> PGF -> PGF