CakeML/cakeml

Refactor to use extended numerals.

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#1,167 opened on May 1, 2025

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dev experiencegood first issuerefactoring

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Description

Cakeml currently uses num option in various places where an extended numeral is more appropriate.

for example in wordlang stack_size is a num option where NONE means the stack is unbounded. This result in slightly unintuitive defintions written in ways like OPTION_MAP2 $+ a b option_le defined with option_le SOME _ NONE. Proof are also harder where many just end up case splitting on the option.

On brief search in the HOL repo there appears to be xnum developed in examples/HolCheck/ctlScript.sml. That should probably be refactored out into a separate file + more syntax sugar to allow stuff like 0e to be a 0 : xnum

Contributor guide

Research direction
Familiarize yourself with the existing use of `num option` in the CakeML source and the xnum type in examples/HolCheck/ctlScript.sml, then propose a refactoring plan to replace `num option` with xnum and add syntax sugar for extended numerals.
Tech stack
None
Domain
compilers
Issue type
Refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Standard MLHOL
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70