sequences.frozen: adding virtual "frozen" sequences.

extra/sequences/frozen/authors.txt

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+John Benediktsson

extra/sequences/frozen/frozen-tests.factor

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+USING: arrays kernel sequences sequences.frozen
+sequences.private tools.test ;
+
+{ { 1 2 3 } } [ { 1 2 3 } <frozen> >array ] unit-test
+
+[ 1 1 { 1 2 3 } <frozen> set-nth ] [ immutable? ] must-fail-with
+
+{ "abc" } [ "abc" <frozen> dup like ] unit-test

extra/sequences/frozen/frozen.factor

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+! Copyright (C) 2009 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+USING: accessors sequences ;
+IN: sequences.frozen
+
+TUPLE: frozen { seq read-only } ;
+
+C: <frozen> frozen
+
+M: frozen virtual@ seq>> ;
+
+M: frozen virtual-exemplar seq>> ;
+
+M: frozen length seq>> length ;
+
+INSTANCE: frozen virtual-sequence
+
+INSTANCE: frozen immutable-sequence

extra/sequences/frozen/summary.txt

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+Virtual "frozen" sequences