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digitalmars.D.bugs - [Issue 7456] New: Purity strength not documented

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=7456

           Summary: Purity strength not documented
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: websites
        AssignedTo: nobody puremagic.com
        ReportedBy: robert octarineparrot.com



17:24:48 GMT ---
The concepts of strong/weak purity are not documented (seems to be discussed in
this thread:
http://lists.puremagic.com/pipermail/dmd-beta/2011-July/000728.html ).

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parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=7456


Jonathan M Davis <jmdavisProg gmx.com> changed:

           What    |Removed                     |Added
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                 CC|                            |jmdavisProg gmx.com



PST ---
There is some debate as to whether they even should be. pure is defined quite
correctly in the spec. weak vs strong purity is arguably just an implementation
detail used for optimizations. I believe that this is Don's take on it (he's
both the one who came up with strong vs weak purity and the one who updated the
spec when pure was changed).

Now, weak vs strong purity inevitably comes up when people get confused by why
the compiler allows what are weakly pure functions to be pure (particularly
when compared with what TDPL says - though I think that many just look at it
from a functional perspective and are confused even without having read TDPL).
So, there is arguably merit in defining them somewhere. But I believe that
Don's against it. He's mentioned before that he wants the terms to go away
entirely.

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