josdejong/mathjs

Evaluating 'help(not)' throws SyntaxError

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#1905 opened on Jul 3, 2020

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 (7 comments) (0 reactions) (0 assignees)JavaScript (13,832 stars) (1,298 forks)batch import
bughelp wanted

Description

For some reason, evaluating help(not) throws an error. For example:

// Works fine
console.log(math.evaluate('help(and)'));

// "SyntaxError: Value expected (char 9)"
console.log(math.evaluate('help(not)'));

Please see this jsfiddle example.

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
bug
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.
1-3 hours
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
JavaScriptbasic understanding of mathjs parser
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The bug is that `help(not)` causes a SyntaxError while `help(and)` works. The issue is likely in the parsing logic for the `help` function, specifically how it handles unary operators like 'not'. Look at the parser source code (likely in `src/parse.js`) to see how `and` is handled versus `not`. The fix may involve adding 'not' to the set of recognized symbols for the help function or adjusting the expression parsing to not treat 'not' as a standalone value. Check the comments on the issue for any additional context or suggested approaches.