From f37d49367c1ce59ae35dda124d85f9732d0cb484 Mon Sep 17 00:00:00 2001
From: Uko Kokņevičs
Date: Sat, 24 Aug 2024 03:08:23 +0800
Subject: Add tuples.

---
 grammar.bnf | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'grammar.bnf')

diff --git a/grammar.bnf b/grammar.bnf
index a9e21cb..8715ad2 100644
--- a/grammar.bnf
+++ b/grammar.bnf
@@ -14,17 +14,21 @@ binop ::= '*' | '/' | '+' | '-' | '?=' | '/=' | '>' | '>=' | '<' | '<=';
 unop ::= '+' | '-' | '!';
 simple-expression ::= '(' expression ')'
                     | 'true' | 'false'
-                    | '(' ')'
                     | INTEGER
                     | IDENTIFIER
                     | STRING
                     | array
+                    | tuple
                     | if-else-expression
                     | let-in-expression
                     | fn-expression
                     | do-expression;
 
 array ::= '[' ']' | '[' expression (',' expression)* ','? ']';
+// Note that tuples always have either zero or at least two elements
+// A tuple with only one element is just '(' expression ')' -- a parenthese-wrapped expression
+// Also '(' expression ',' ')' is illegal
+tuple ::= '(' ')' | '(' expression ',' expression (',' expression)* ','? ')';
 
 if-else-expression ::= 'if' expression 'then' expression 'else' expression;
 let-in-expression ::= 'let' def-spec '=' expression ('and' def-spec '=' expression)* 'in' expression;
-- 
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