From df0c370059859758e899b0379b64559b129da927 Mon Sep 17 00:00:00 2001
From: Brandon Dyck <brandon@dyck.us>
Date: Thu, 29 Jun 2023 10:55:13 -0600
Subject: [PATCH] Added let-exprs to grammar, and fixed patterns

---
 grammar.txt | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/grammar.txt b/grammar.txt
index 73af91c..962dfe0 100644
--- a/grammar.txt
+++ b/grammar.txt
@@ -3,7 +3,7 @@ expression ->
 //	| apply
 	| unary
 	| binary
-//	| let
+	| let
 	| compound
 	| control
 	| field
@@ -17,16 +17,19 @@ binary -> expression operator expression ;
 operator ->
 	| "==" | "!=" | "<" | "<=" | ">" | ">="
 	| "+" | "-" | "*" | "/"
-//	| "|>" | "<|" | ">>" | "<<"
+	| "|>" | "<|" | ">>" | "<<"
 	| "++" ;
+pattern -> "_" | record_pattern | variant_pattern | identifier ;
+record_pattern -> "{" ( identifier ( "=" pattern )? ( "," identifier ( "=" pattern )? )* ) ( "|" identifier ) "}"
+variant_pattern -> "`" identifier ( "(" ( "_" | compound_pattern | identifier ) ")" )? ;
+let -> "let" pattern "=" expression ( "and" pattern "=" expression )* "in" expression ;
 control ->
 	| if
 	| when
 if -> "if" expression "then" expression "else" expression ;
-variant_pattern -> "`" identifier ( "(" ( ( "_" | identifier ) ( "," ( "_" | identifier )* )? ) ")" )? ;
-when -> "when" expression "is" ( variant_pattern "=>" expression )+ ;
+when -> "when" expression "is" ( pattern "=>" expression )+ ;
 compound -> variant | record | list ;
-variant -> "`" identifier ( "(" ( expression ( "," expression)* )? ")" )? ;
+variant -> "`" identifier ( "(" expression ")" )? ;
 base_record -> expression ( "with" identifier "=" expression ( "," "with" identifier "=" expression )* )?
 record ->
 	"{" ( identifier ("=" expression)? ( "," identifier ("=" expression)? )* )? ( "|" base_record )* "}" ;