Add indices word

core/sequences/sequences-tests.factor

@@ -265,4 +265,6 @@ M: bogus-hashcode hashcode* 2drop 0 >bignum ;
 
 [ { 1 3 7 } ] [ 2 { 1 3 5 7 } remove-nth ] unit-test
 
-[ { 1 3 "X" 5 7 } ] [ "X" 2 { 1 3 5 7 } insert-nth ] unit-test
+[ { 1 3 "X" 5 7 } ] [ "X" 2 { 1 3 5 7 } insert-nth ] 
+
+[ V{ 0 2 } ] [ "a" { "a" "b" "a" } indices ] unit-test

core/sequences/sequences.factor

@@ -480,6 +480,11 @@ PRIVATE>
 : last-index-from ( obj i seq -- n )
     rot [ = ] curry find-last-from drop ;
 
+: indices ( obj seq -- indices )
+    V{ } clone spin
+    [ rot = [ over push ] [ drop ] if ]
+    curry each-index ;
+
 : nths ( seq indices -- seq' )
     swap [ nth ] curry map ;