TaggedArrays (Proposal)

[Mark Roos]

>From Rémi on static analysis for loops

        Not having such kind of analysis is almost a crime.

For a language like Smalltalk I was thinking that having such an analysis
would be the work of the gods.

With user overridable methods, reflection and run time code creation I 
have only found a few
places where I could do such an static analysis.  And those are fragile. 

So do you have a good paper that would apply?  I have looked at many from 
the 80s/90s and
have yet to find a general approach for a Smalltalk style language.

I am thinking of adding a mutable flag to integers so I can share a body 
but 'lazy' freeze to
a real integer but it seems like I'll be adding lots of checks just to fix 
what could be a small problem
over an entire application.

I also have a thought to allocate a few primitive slots in each stack 
frame to pass real primitives 
but again I have to test everywhere for which slot is valid.

The best thought may be to add patterns to the language to avoid the use 
of visible integers
as indexes  ( e.g. instead of '1 to:3 do:[aBlock over a collection]' do 
'aCollection from:1 to:3 do:[ aBlock on each indexed item]')
Now I can do the static analysis.  As they say 'If it hurts don't do it'

regards
mark
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