Associativity of matmul unclear from grammar for m_expr
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Description
Documentation
6.7. Binary arithmetic operations shows the grammar rule
m_expr ::= u_expr | m_expr "*" u_expr | m_expr "@" m_expr |
m_expr "//" u_expr | m_expr "/" u_expr |
m_expr "%" u_expr
in which all operators except @ for matmul are left-associative (meaning, a*b*c parses as m_expr a*b and u_expr c ) while @ is ambiguous: Does a@b@c parse as m_expr a@b and m_expr c or as m_expr a and m_expr b@c?
According to PEP 465, @ should have the same associativity as *. Should this grammar rule should reflect that by saying m_expr "@" u_expr, that is, with the right-hand side changed from m_expr to u_expr?
Linked PRs
- gh-138847
- gh-145636
- gh-149281
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the 6.7 Binary arithmetic operations section linked in the issue and compare its m_expr grammar with the associativity specified in PEP 465. Review linked PRs gh-138847, gh-145636, and gh-149281; done means the documentation makes @ associativity unambiguous and matches the specification.
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Assessment
- Tech stack
- python
- Domain
- documentation
- Issue type
- Documentation
- Difficulty
- 1/5
- Estimated time
- Under an hour
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 30/100