Functions added to sequences.lib; used in shufflers

extra/sequences/lib/lib-tests.factor

@@ -1,5 +1,5 @@
 USING: arrays kernel sequences sequences.lib math
-math.functions tools.test ;
+math.functions tools.test strings ;
 
 [ 4 ] [ { 1 2 } [ sq ] [ * ] map-reduce ] unit-test
 [ 36 ] [ { 2 3 } [ sq ] [ * ] map-reduce ] unit-test
@@ -42,3 +42,7 @@ math.functions tools.test ;
 
 [ { 1 9 25 } ] [ { 1 3 5 6 } [ sq ] [ even? ] map-until ] unit-test
 [ { 2 4 } ] [ { 2 4 1 3 } [ even? ] take-while ] unit-test
+
+[ { { 0 0 } { 1 0 } { 0 1 } { 1 1 } } ] [ 2 2 exact-strings ] unit-test
+[ t ] [ "ab" 4 strings [ >string ] map "abab" swap member? ] unit-test
+[ { { } { 1 } { 2 } { 1 2 } } ] [ { 1 2 } power-set ] unit-test

extra/sequences/lib/lib.factor

@@ -1,5 +1,5 @@
-USING: combinators.lib kernel sequences math namespaces
-random sequences.private shuffle ;
+USING: combinators.lib kernel sequences math namespaces assocs 
+random sequences.private shuffle math.functions mirrors ;
 IN: sequences.lib
 
 ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@@ -74,3 +74,33 @@ IN: sequences.lib
     [ not ] compose
     [ find drop [ head-slice ] when* ] curry
     [ dup ] swap compose keep like ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+<PRIVATE
+: translate-string ( n alphabet out-len -- seq )
+    [ drop /mod ] curry* map nip  ;
+
+: map-alphabet ( alphabet seq[seq] -- seq[seq] )
+    [ [ swap nth ] curry* map ] curry* map ;
+
+: exact-number-strings ( n out-len -- seqs )
+    [ ^ ] 2keep [ translate-string ] 2curry map ;
+
+: number-strings ( n max-length -- seqs )
+    1+ [ exact-number-strings ] curry* map concat ;
+PRIVATE>
+
+: exact-strings ( alphabet length -- seqs )
+    >r dup length r> exact-number-strings map-alphabet ;
+
+: strings ( alphabet length -- seqs )
+    >r dup length r> number-strings map-alphabet ;
+
+: nths ( nths seq -- subseq )
+    ! nths is a sequence of ones and zeroes
+    >r [ length ] keep [ nth 1 = ] curry subset r>
+    [ nth ] curry { } map-as ;
+
+: power-set ( seq -- subsets )
+    2 over length exact-number-strings swap [ nths ] curry map ;

extra/shufflers/shufflers.factor

@@ -1,25 +1,14 @@
 USING: kernel sequences words math math.functions arrays 
 shuffle quotations parser math.parser strings namespaces 
-splitting effects ;
+splitting effects sequences.lib ;
 IN: shufflers
 
 : shuffle>string ( names shuffle -- string )
     swap [ [ nth ] curry map ] curry map
     first2 "-" swap 3append >string ;
 
-: translate ( n alphabet out-len -- seq )
-    [ drop /mod ] curry* map nip  ;
-
-: (combinations) ( alphabet out-len -- seq[seq] )
-    [ ^ ] 2keep [ translate ] 2curry map ;
-
-: combinations ( n max-out -- seq[seq] )
-    ! This returns a seq of length O(n^m)
-    ! where and m is max-out
-    1+ [ (combinations) ] curry* map concat ;
-
 : make-shuffles ( max-out max-in -- shuffles )
-    [ 1+ dup rot combinations [ 2array ] curry* map ]
+    [ 1+ dup rot strings [ 2array ] curry* map ]
     curry* map concat ;
 
 : shuffle>quot ( shuffle -- quot )