markov-chains: initial implementation.

extra/markov-chains/authors.txt

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+John Benediktsson

extra/markov-chains/markov-chains.factor

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+! Copyright (C) 2020 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+
+USING: assocs assocs.extras assocs.private fry grouping kernel
+math.extras random sequences ;
+
+IN: markov-chains
+
+: transitions ( string -- clumps )
+    { t } { f } surround 2 clump ;
+
+: push-transitions ( table seq -- table )
+    transitions over [
+        [ drop H{ } clone ] cache inc-at
+    ] with-assoc assoc-each ;
+
+: transition-table ( seq -- table )
+    H{ } clone swap [ push-transitions ] each ;
+
+: markov-chain ( table -- seq )
+    t swap '[ _ at weighted-random dup ] [ dup ] produce nip ;

extra/markov-chains/summary.txt

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+Markov chain processes.