2 days ago
- JSON's lack of trailing commas complicates adding or removing key-value pairs, requiring different transformations than if trailing commas were allowed.
- Haskell's record syntax uses leading commas, making it easier to modify the last row but harder to change the first.
- TLA+ disallows trailing commas, causing frequent issues when adding variables, while its PlusCal extension does not have this problem.
- Prolog uses a period to terminate rules, not a trailing separator, which can lead to parsing ambiguity if commas were used instead.
- Languages like Go and Python allow trailing commas in data structures but not leading commas, while Alloy permits both leading and trailing commas.
- Arguments against trailing separators include parsing ambiguity, as seen in Prolog rule boundaries and Ruby method chaining.
- Python uses a trailing comma to distinguish a single-element tuple from a parenthesized expression, showing an edge case benefit.