gleam-lang/gleam

Determine why this code causes the Erlang compiler to run for a very long time

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#4,985 opened on Sep 17, 2025

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help wanted

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Description

When Erlang inlining is enabled this code takes extreme amounts of time to compile: https://github.com/bondiano/telega-gleam/blob/33b3bfc2b7c45cd88d52e3edd4f45d9740190eb0/src/telega/update.gleam#L225

The long change of use expressions seems to be related. Let's determine a minimal reproduction in Erlang so we can report the bug to the Erlang folks.

Thanks to @sean-hale-dev for finding this and @bondiano for initial investigation

Prior discussion https://github.com/bondiano/telega-gleam/issues/27

Contributor guide

Research direction
Inspect the long chain of use expressions in the Gleam code at the linked location. Compile with inlining enabled to reproduce the long compilation time. Then minimize the repro to a pure Erlang example to report upstream.
Tech stack
None
Domain
tooling
Issue type
Bug
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.
1-2 days
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.
Mostly clear
Prerequisites
ErlangGleam
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20