.. is concatenation

lexer.l

@@ -42,6 +42,7 @@ elif 					return ELIF;
 {letter}({letter}|{digit}|[?.-])*	yylval.sym = yytext; return ID;
 "<-"					return GETS;
 "->"					return MAPS;
+".."					return CAT;
 [(){}.,*/+-]				return yytext[0];
 [\t ]					// Eat whitespace not first on a line
 "/"\n					// Eat newlines ending in /

parser.y

@@ -19,6 +19,7 @@ int yyerror(const char* p) { fprintf(stderr, p); }
 %token IF ELIF ELSE
 
 %right GETS
+%left CAT
 %left '+' '-'
 %left '/' '*'
 %left MAPS
@@ -34,6 +35,7 @@ assignments: 	assignments assignment STOP | // null production;
 expr:		funcdef
 		| funcall
 		| objdef
+		| expr CAT expr
 		| expr '+' expr
 		| expr '-' expr
 		| expr '*' expr