wiki:CaseSensitivity

Historically one of the most heated flame-wars in the Scheme community. We have to decide whether we want to preserve backwards compatibility with standards up through the R5RS, or reaffirm the switch to case-sensitivity in the R6RS. The charter gives precedence to the former, so unless we can reach a rough consensus (> 90%) to the contrary, the default should remain case-insensitive.

Whatever we choose we should realize that some implementations are likely to use a different default in their preferred environments.

Note that the default case-sensitivity is orthogonal to the issue of whether and how behavior can be toggled on a per-file or per-expression basis. If there is a toggle, it may be specified by WG1 for both groups, or only by WG2.

Below are some common arguments for each side. The number of arguments on each side is irrelevant - people should weigh each argument according to its importance.

Pro-folding:

  • R[0-5]RS and IEEE Scheme compatible
  • possibly easier for beginners not expecting case distinctions to be significant
  • allows using different cases as stylistic differences in source
  • prevents using separate identifiers which differ only in case, which is considered poor style
  • less confusion when code is read aloud, e.g. variable names

Pro-preserving:

  • R6RS compatible
  • the popular default in a number of modern implementations
  • easier compatibility with external data (XML, some filesystems, FFIs)
  • users from other languages usually expect case sensitivity
  • using different cases for the same identifier can be confusing
  • transliterations of math formulae may be easier to read with case distinctions
  • more general - can write a (begin/ci ...) macro to implement the alternative
  • allows using separate identifiers which differ only in case (e.g., capitalizing a class but not an instance)
  • simpler to implement in the presence of complex character sets
  • most programmers won't be able to recognize case-folded equivalents from languages they don't speak

Proposals:

Last modified 7 years ago Last modified on 03/14/10 07:40:22