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.

Pro-folding:

• R[0-5]RS and IEEE Scheme compatible
• code from R5RS and before continues to work
• 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

Pro-preserving:

• R6RS compatible
• the popular default in a number of modern implementations
• easier compatibility with external data (XML, some filesystems, FFIs)
• 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