Allow function literals in constants

Description

type FunctionWrapper {
  FunctionWrapper(fn(String) -> Int)
}
const my_function = FunctionWrapper(fn(something) { 0 })

Contributor guide

Tech stack

rust

Domain

developer experience

Issue type

feature

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

fresh

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

Understanding of Gleam syntaxBasic Rust programming

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

60

Research direction

This issue proposes allowing function literals in constant expressions. To implement this, examine the Gleam compiler's handling of constants and function literals. Look at the parser module for how constants are parsed and the type checker for how function types are inferred. The existing code defines constants as simple expressions, and function literals may require extending the constant expression grammar. Review comments on the issue for any maintainer guidance. The change is localized to the parser and type checker, and should be straightforward given the well specified example.