[Haskell] A puzzle and an annoying feature
gk at ninebynine.org
Fri Nov 26 06:27:17 EST 2004
At 19:14 25/11/04 +0100, Lennart Augustsson wrote:
>Graham Klyne wrote:
>>I have a concern with this, if I understand the issue correctly.
>>Suppose I have a source module that compiles and runs correctly.
>>Now suppose I add a restricted (selective) import statement to the file,
>>explicitly introducing a name that I know does not clash with anything in
>>my module. I expect the module to continue to compile and run correctly.
>>If I understand Lennart's proposal correctly, adding such an import could
>>cause the compilation to fail, by adding new instance options that then
>>needs to be disambiguated.
>Not in my particular case. The class is local to the module. Any
>instance declaration would have to be in that module.
OK, I missed that.
But, it seems to me, that adding export of the class concerned to the
module heading could raise a similar scenario to that mentioned. It's less
clear-cut, but it seems surprising to me that the choice of whether or not
to export something from a module should (potentially) change its meaning
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