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[Gcl-devel] arrays

From: Camm Maguire
Subject: [Gcl-devel] arrays
Date: 04 Sep 2005 23:38:24 -0400
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2


What is '(array nil) suposed to mean?

I noticed that cmucl has support for 1 2 4 8 16 and 32bit array
integers.  GCL has 1, 8, 16 and 32 (on 32bit machines).

1) Is there any real benefit to 2 and 4 bit integer types, considering
   the access overhead vs space tradeoff?
2) My understanding is that the simple (signed-byte
   2^n),(unsigned-byte 2^n) strategy will not pass all Paul's tests,
   as upgraded-array-element-type must preserve subtypep relationships
   -- one needs at least (unsigned-byte 2^n-1), etc.
   I.e. non-negative-char, signed-char, and (optionally) (unsigned
   char) for each size type.  This is what I've implemented at
   present, and I'm passing all relevant tests.  I'd obviously like to
   support the minimum number of types possible, if for no other
   reason than it slows down subtypep et. al. on (array *).

Take care,

Camm Maguire                                            address@hidden
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah

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