[cknitt]

Adds getWithDefault and getOrThrow to Belt.HashMap, Belt.HashMap.Int and Belt.HashMap.String. They walk the bucket directly (no option allocated) and getOrThrow throws Not_found, like the other Belt maps.

The issue asks for getOr; Belt names this lookup getWithDefault everywhere (Option, Map, MutableMap) and has no getOr, so the new function follows Belt.

Fixes #8381.

New tests: mocha cases in tests/belt_tests/src/belt_hashmap_test.res (generic map, a map whose keys all collide into one bucket, Int and String variants) and docstring examples for each new function.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Kr4cjoUi2f5VpMvE6wT9bo

[github-actions]

Changelog

🚀 New Feature

• Add getWithDefault and getOrThrow to Belt.HashMap, Belt.HashMap.Int and Belt.HashMap.String.

Semantic Diff

1 commit · Full page

✏️ Add getWithDefault and getOrThrow to Belt.HashMap

_{43bce48 · cknitt + Claude · Oct 19, 2026, 19:55 UTC · edited}

Belt.HashMap, Belt.HashMap.Int and Belt.HashMap.String gain getWithDefault and getOrThrow, the same lookups Belt.Map and Belt.MutableMap already have. They walk the bucket directly, so a hit allocates no option; getOrThrow throws Not_found like the other Belt maps.

let m = Belt.HashMap.Int.fromArray([(1, "a")])
m->Belt.HashMap.Int.getWithDefault(2, "z") == "z"
m->Belt.HashMap.Int.getOrThrow(1) == "a"

Review

• Why getWithDefault and not getOr, as the issue title says? Belt names this lookup getWithDefault everywhere (Option, Map, MutableMap and their Int/String variants) and has no getOr; the new functions follow Belt. getOrThrow is the name Belt already uses, without a deprecated getExn alias for a new API.

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commit: 43bce48

[github-actions]

Developer playground preview: https://rescript-lang.github.io/rescript/dev-playground/?version=pr-8926

[cknitt]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-20T06:08:37.857188Z	1e7faef	Manual request

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Delightful!

Reviewed commit: 1e7faef13f

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