fix: allow decorators before and in let bindings

Author: nkrkv

grammar.js

@@ -71,6 +71,7 @@ module.exports = grammar({
     [$.record_field, $.record_pattern],
     [$.expression_statement, $.ternary_expression],
     [$._type_declaration],
+    [$._let_binding],
     [$.let_binding, $.ternary_expression],
     [$.variant_identifier, $.module_identifier],
     [$.variant],
@@ -434,13 +435,19 @@ module.exports = grammar({
         '=',
         repeat($.decorator),
         $.expression,
-        optional(seq(
-          'and',
-          $._let_binding,
-        )),
+        repeat(alias($._let_binding_and, $.let_binding)),
       )),
     ),
 
+    _let_binding_and: $ => seq(
+      // New line here not necessary terminates the statement,
+      // show this doubt to the parser
+      repeat($._newline),
+      repeat($.decorator),
+      'and',
+      $._let_binding,
+    ),
+
     _binding_pattern: $ => choice(
       $.value_identifier,
       $.tuple_pattern,

test/corpus/let_bindings.txt

@@ -200,11 +200,12 @@ let a = 5 and b = 4
   (let_binding
     (value_identifier)
     (number)
-    (value_identifier)
-    (number)))
+    (let_binding
+      (value_identifier)
+      (number))))
 
 ============================================
-And (Fuctions)
+And (Functions)
 ============================================
 
 let rec a = x => x + b(x) and b = y => y - 1
@@ -222,10 +223,40 @@ let rec a = x => x + b(x) and b = y => y - 1
           (value_identifier)
           (arguments
             (value_identifier)))))
-    (value_identifier)
-    (function
+    (let_binding
       (value_identifier)
-      (binary_expression
+      (function
+        (value_identifier)
+        (binary_expression
+          (value_identifier)
+          (number))))))
+
+============================================
+And (decorated)
+============================================
+
+@one
+let rec a = b
+@two @three
+and b = c
+
+@four and c = 42
+
+---
+
+(source_file
+  (decorated
+    (decorator (decorator_identifier))
+    (let_binding
+      (value_identifier)
+      (value_identifier)
+      (let_binding
+        (decorator (decorator_identifier))
+        (decorator (decorator_identifier))
+        (value_identifier)
+        (value_identifier))
+      (let_binding
+        (decorator (decorator_identifier))
         (value_identifier)
         (number)))))