Allow relation symbols with parameters

Parameters must follow the relation symbol and be surrounded by braces, like so: `\rel{x}{y}{z}`.

This attempt is still brittle/broken in a few ways:
- It makes using braces in creative ways in mixfix notation ambiguous.
- It does not verify that the parameters are used in a consistent manner for each symbol. It essentially allows users to define  `a\MyRel b` and `a\MyRel{x} b` (and ones with even more parameters).
- It allows parameters for all relation symbols, even for those where it makes no sense in ordinary TeX markup, e.g. `a <{x} b`.

1 files changed, 4 insertions, 4 deletions

diff --git a/source/Syntax/Concrete.hs b/source/Syntax/Concrete.hs
index 383f348..3c6700b 100644
--- a/source/Syntax/Concrete.hs
+++ b/source/Syntax/Concrete.hs
@@ -84,8 +84,8 @@ grammar lexicon@Lexicon{..} = mdo
     relationSign   <- rule $ pure Positive <|> (Negative <$ command "not")
     relationExpr   <- rule $ RelationExpr <$> (command "mathrel" *> group expr)
     relation       <- rule $ (RelationSymbol <$> relator) <|> relationExpr
-    chainBase      <- rule $ ChainBase <$> exprs <*> relationSign <*> relation <*> exprs
-    chainCons      <- rule $ ChainCons <$> exprs <*> relationSign <*> relation <*> chain
+    chainBase      <- rule $ ChainBase <$> exprs <*> relationSign <*> relation <*> many (brace expr) <*> exprs
+    chainCons      <- rule $ ChainCons <$> exprs <*> relationSign <*> relation <*> many (brace expr) <*> chain
     chain          <- rule $ chainCons <|> chainBase
 
     formulaPredicate  <- rule $ asum $ prefixPredicateOf FormulaPredicate expr <$> HM.keys lexiconPrefixPredicates
@@ -250,7 +250,7 @@ grammar lexicon@Lexicon{..} = mdo
     defnAdj <- rule $ DefnAdj <$> optional (_an *> nounPhrase) <*> var <* _is <*> adjVar
     defnVerb <- rule $ DefnVerb <$> optional (_an *> nounPhrase) <*> var <*> verbVar
     defnNoun <- rule $ DefnNoun <$> var <* _is <* _an <*> nounVar
-    defnRel <- rule $ DefnRel <$> (beginMath *> varSymbol) <*> relator <*> varSymbol <* endMath
+    defnRel <- rule $ DefnRel <$> (beginMath *> varSymbol) <*> relator <*> many (group varSymbol) <*> varSymbol <* endMath
     defnSymbolicPredicate <- rule $ math $ asum $ prefixPredicateOf DefnSymbolicPredicate varSymbol <$> HM.keys lexiconPrefixPredicates
     defnHead <- rule $ optional _write *> asum [defnAdj, defnVerb, defnNoun, defnRel, defnSymbolicPredicate]
 
@@ -269,7 +269,7 @@ grammar lexicon@Lexicon{..} = mdo
     abbreviationVerb  <- rule $ AbbreviationVerb <$> var <*> verbVar <* (_iff <|> _if) <*> stmt <* _dot
     abbreviationAdj   <- rule $ AbbreviationAdj <$> var <* _is <*> adjVar <* (_iff <|> _if) <*> stmt <* _dot
     abbreviationNoun  <- rule $ AbbreviationNoun <$>  var <* _is <* _an <*> nounVar <* (_iff <|> _if) <*> stmt <* _dot
-    abbreviationRel   <- rule $ AbbreviationRel <$> (beginMath *> varSymbol) <*> relator <*> varSymbol <* endMath <* (_iff <|> _if) <*> stmt <* _dot
+    abbreviationRel   <- rule $ AbbreviationRel <$> (beginMath *> varSymbol) <*> relator <*> many (brace varSymbol) <*> varSymbol <* endMath <* (_iff <|> _if) <*> stmt <* _dot
     abbreviationFun   <- rule $ AbbreviationFun <$> (_the *> funVar) <* (_is <|> _denotes) <*> term <* _dot
     abbreviationEq    <- rule $ uncurry AbbreviationEq <$> symbolicPatternEqTerm
     abbreviation      <- rule $ (abbreviationVerb <|> abbreviationAdj <|> abbreviationNoun <|> abbreviationRel <|> abbreviationFun <|> abbreviationEq)