Add support for curried dot operator (.)

corpus/basic.txt

@@ -732,3 +732,49 @@ scientific notation
           (record_operand
             (atom
               (num_literal))))))))
+
+================================================================================
+curried dot operator
+================================================================================
+
+"foo"
+|> (.) { foo = "bar" }
+
+--------------------------------------------------------------------------------
+
+(term
+  (uni_term
+    (infix_expr
+      (infix_expr
+        (applicative
+          (record_operand
+            (atom
+              (str_chunks
+                (str_chunks_single
+                  (chunk_literal_single
+                    (str_literal))))))))
+      (infix_b_op_6)
+      (infix_expr
+        (applicative
+          (applicative
+            (record_operand
+              (atom
+                (curried_op))))
+          (record_operand
+            (atom
+              (uni_record
+                (record_last_field
+                  (record_field
+                    (field_path
+                      (field_path_elem
+                        (ident)))
+                    (term
+                      (uni_term
+                        (infix_expr
+                          (applicative
+                            (record_operand
+                              (atom
+                                (str_chunks
+                                  (str_chunks_single
+                                    (chunk_literal_single
+                                      (str_literal))))))))))))))))))))

grammar.js

@@ -491,6 +491,15 @@ module.exports = grammar({
     //grammar.lalrpop: 617
     curried_op: $ => choice(
       $.infix_op,
+      // Field access isn't a proper infix operator, it's a form with special
+      // treatment (in particular because the second argument isn't necessarily
+      // a string but can be a statically known identifier, which can't be
+      // encoded as a generic operator application). It is thus not included in
+      // `infix_op`.
+      //
+      // Still, Nickel allows to use it as a curried operator as in `(.) foo
+      // bar`, so we add it here manually.
+      ".",
       // NOTE: Removed, see NOTE[special-infix].
       //"|>",
       //"!=",

src/grammar.json

@@ -1772,6 +1772,10 @@
         {
           "type": "SYMBOL",
           "name": "infix_op"
+        },
+        {
+          "type": "STRING",
+          "value": "."
         }
       ]
     },

src/node-types.json

@@ -309,7 +309,7 @@
     "fields": {},
     "children": {
       "multiple": false,
-      "required": true,
+      "required": false,
       "types": [
         {
           "type": "infix_op",