Simon Peyton-Jones wrote:
My suggestion is this:
* Specify MPTCs in the main language
* Specify FDs in an Appendix (with some reasonably conservative interpretation of FDs).
* A Haskell' implementation should implement the Appendix, and programmers can write programs against it. But we are advertising specifically that we aren't sure, one way or the other, whether FDs will stay in the language for ever
Simon, Why is an Appendix is better than just a footnote in the Standard that says "we aren't sure, one way or the other, whether FDs will stay in the language for ever." Why do we need this extra structure? I'm worried that this extra structure could be confusing. In particular, if someone says "this program is pure Haskell'" what will that mean? In practice, will it be clear whether pure Haskell' includes the Appendix? --Stephanie