diff --git a/extra/sequences/extras/extras-tests.factor b/extra/sequences/extras/extras-tests.factor
index 27e73e954b..45f08db319 100644
--- a/extra/sequences/extras/extras-tests.factor
+++ b/extra/sequences/extras/extras-tests.factor
@@ -1,4 +1,4 @@
-USING: kernel make math sequences sequences.extras tools.test ;
+USING: ascii kernel make math sequences sequences.extras tools.test ;
 
 IN: sequences.extras.tests
 
@@ -33,3 +33,15 @@ IN: sequences.extras.tests
 ] unit-test
 
 [ { 1 3 5 } ] [ { 1 2 3 4 5 6 } [ nip even? ] filter-index ] unit-test
+
+[ V{ 1 3 5 } ] [ { 1 2 3 4 5 6 } [ nip even? ] V{ } filter-index-as ] unit-test
+
+[ { 1 3 5 } ] [ { 1 2 3 4 5 6 } even-indices ] unit-test
+
+[ { 2 4 6 } ] [ { 1 2 3 4 5 6 } odd-indices ] unit-test
+
+{ "a b c d e" }
+[ "a      b  \t \n \r  c   d \n    e   " [ blank? ] " " compact ] unit-test
+
+{ " a b c d e " }
+[ " a      b  c   d    e   " [ blank? ] " " collapse ] unit-test
diff --git a/extra/sequences/extras/extras.factor b/extra/sequences/extras/extras.factor
index 1a5fd293b6..10a743e868 100644
--- a/extra/sequences/extras/extras.factor
+++ b/extra/sequences/extras/extras.factor
@@ -1,5 +1,5 @@
 USING: arrays grouping kernel locals math math.order math.ranges
-sequences ;
+sequences splitting ;
 
 IN: sequences.extras
 
@@ -81,3 +81,17 @@ IN: sequences.extras
 
 : filter-index ( ... seq quot: ( ... elt i -- ... ? ) -- ... seq' )
     over filter-index-as ; inline
+
+: even-indices ( seq -- seq' ) [ nip even? ] filter-index ;
+
+: odd-indices ( seq -- seq' ) [ nip odd? ] filter-index ;
+
+: compact ( seq quot elt -- seq' )
+    [ split-when harvest ] dip join ; inline
+
+: collapse ( seq quot elt -- seq' )
+    [ split-when ] dip
+    [ [ harvest ] dip join ]
+    [ [ first empty? ] dip [ prepend ] curry when ]
+    [ [ last empty? ] dip [ append ] curry when ]
+    2tri ; inline