Add support for dict syntax

[nojaf]

Claude and I had a chat about this. I'm no expert on treesitter but this all seems legit to me from afar.

[Copilot]

Pull request overview

This PR adds support for dict (dictionary) syntax to the ReScript tree-sitter grammar, enabling parsing of dict expressions and dict patterns in switch statements. The implementation follows the established patterns used for similar constructs like lists and arrays.

Changes:

• Added dict expression and dict_pattern grammar rules with support for key-value pairs
• Added syntax highlighting for dict constructs
• Added test cases covering dict expressions and dict patterns in switch statements
• Updated build infrastructure (Node.js version, CI config, rescript dependency, documentation)

Reviewed changes

Copilot reviewed 9 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
grammar.js	Added dict and dict_pattern rules with dict_entry/dict_pattern_entry, added dict/dict_pattern conflict resolution
src/grammar.json	Auto-generated grammar representation reflecting dict additions
src/node-types.json	Auto-generated AST node type definitions for dict, dict_entry, dict_pattern, dict_pattern_entry
test/corpus/expressions.txt	Added test cases for dict expressions and dict pattern matching in switch statements
queries/highlights.scm	Added syntax highlighting rules for dict constructs, marking "dict" keyword as type.builtin and keys as properties
package.json	Added rescript ^12.0.2 as devDependency
package-lock.json	Added rescript and its platform-specific optional dependencies
CLAUDE.md	Added new documentation file with build commands, architecture overview, and development workflow
.nvmrc	Updated Node.js version from v23.7.0 to v24.11.1
.github/workflows/ci.yml	Added Node.js setup step using .nvmrc for version consistency

Comments suppressed due to low confidence (1)

test/corpus/expressions.txt:1966

• Consider adding more comprehensive test cases for dict expressions to match the coverage provided for similar constructs like lists. Suggested additions: trailing comma test (e.g., dict{"A": 5,}), multiline formatting test, and dict in let binding pattern matching (e.g., let dict{"key": value} = myDict).

================================================================================
Dict expression
================================================================================

dict{"A": 5, "B": 6}
dict{}

--------------------------------------------------------------------------------

(source_file
  (expression_statement
    (dict
      (dict_entry
        (string
          (string_fragment))
        (number))
      (dict_entry
        (string
          (string_fragment))
        (number))))
  (expression_statement
    (dict)))

================================================================================
Dict pattern in switch
================================================================================

switch json {
| Object(dict{"lat": Number(lat)}) => lat
| _ => 0.0
}

--------------------------------------------------------------------------------

(source_file
  (expression_statement
    (switch_expression
      (value_identifier)
      (switch_match
        (variant_pattern
          (variant_identifier)
          (formal_parameters
            (dict_pattern
              (dict_pattern_entry
                (string
                  (string_fragment))
                (variant_pattern
                  (variant_identifier)
                  (formal_parameters
                    (value_identifier)))))))
        (sequence_expression
          (expression_statement
            (value_identifier))))
      (switch_match
        (value_identifier)
        (sequence_expression
          (expression_statement
            (number)))))))

---

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[aspeddro]

@nojaf thank you!!

Take a look at #190 and #189

let dict = dict{"A": 5, "B": 6, "C": 7}

(source_file [0, 0] - [1, 0]
  (ERROR [0, 0] - [0, 39]
    (dict_pattern [0, 4] - [0, 39]
      (ERROR [0, 9] - [0, 15])
      (dict_pattern_entry [0, 16] - [0, 22]
        (string [0, 16] - [0, 19]
          (string_fragment [0, 17] - [0, 18]))
        (number [0, 21] - [0, 22]))
      (dict_pattern_entry [0, 24] - [0, 30]
        (string [0, 24] - [0, 27]
          (string_fragment [0, 25] - [0, 26]))
        (number [0, 29] - [0, 30]))
      (dict_pattern_entry [0, 32] - [0, 38]
        (string [0, 32] - [0, 35]
          (string_fragment [0, 33] - [0, 34]))
        (number [0, 37] - [0, 38])))))

dict can be a valid identifier. The check to determine whether dict{} is an identifier or a dictionary constructor should be done in the lexical analyzer.

tree-sitter-rescript/src/scanner.c

Lines 304 to 322 in d2df8a2

	if (valid_symbols[LIST_CONSTRUCTOR]) {
	lexer->result_symbol = LIST_CONSTRUCTOR;
	if (lexer->lookahead == 'l') {
	advance(lexer);
	if (lexer->lookahead == 'i') {
	advance(lexer);
	if (lexer->lookahead == 's') {
	advance(lexer);
	if (lexer->lookahead == 't') {
	advance(lexer);
	if (lexer->lookahead == '{') {
	lexer->mark_end(lexer);
	return true;
	}
	}
	}
	}
	}
	}

[Copilot]

Pull request overview

Copilot reviewed 13 out of 15 changed files in this pull request and generated 2 comments.

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[aspeddro]

That sounds great!! 🎉