006: Method Calls Without Empty Parentheses

• Status: Accepted
• Author: @ornew
• Date: 2026-10-11

Summary

Allow a method call with no supplied arguments to omit its parentheses:

name:len
name:len()

These spellings make the same call. This also applies to methods whose parameters are all optional: created_at:year and created_at:year() use the same default. A method with required parameters still fails compilation when they are omitted.

Motivation

An empty argument list adds no information to a zero-argument call. Omitting it makes common expressions shorter while preserving explicit parentheses for readers who prefer them. Optional-argument methods already define behavior when called with zero supplied arguments, so the shorthand should work for them as well.

Goals

• Make parentheses optional only when the supplied argument count is zero.
• Preserve existing explicit-call syntax and method resolution.
• Apply the same rule to methods with no parameters and methods whose parameters are all optional.
• Keep missing required arguments as compile-time errors.

Non-goals

This does not add property-style access, free-function calls, implicit method arguments, or a way to omit only some positional arguments.

Design

The syntax specification treats a bare method name after a receiver colon as a zero-argument method call. The compiler then applies the existing signature rules: no-argument methods resolve normally, optional parameters use their existing defaults, and required parameters produce the existing argument-count diagnostic. Explicit empty parentheses remain valid and equivalent.

Because this is syntax sugar, it does not change method IDs, capability selection, result types, null/no-value behavior, source ownership, or backend support. Generated syntax nodes should represent both forms consistently while retaining source spans for the spelling the user wrote.

Alternatives considered

Restricting the shorthand to signatures declared with zero parameters would keep optional-parameter calls visually distinct. It would also make syntax depend on the method catalog before users could understand whether parentheses were required. Treating every no-argument spelling uniformly is simpler; the existing compiler already distinguishes optional from required arguments.

Testing

Parser and compiler conformance should cover explicit and omitted parentheses for zero-argument calls, optional-argument defaults, omitted required arguments, chaining, and source spans. Runtime parity should confirm both spellings produce identical behavior for local and future backends.