diff --git a/factor/parser/Tuple.java b/factor/parser/Tuple.java
index db6a2f5c26..7d287bc0ac 100644
--- a/factor/parser/Tuple.java
+++ b/factor/parser/Tuple.java
@@ -51,6 +51,7 @@ public class Tuple extends FactorParsingDefinition
 		String tupleName = (String)next;
 		reader.intern(tupleName,true);
 		reader.intern("<" + tupleName + ">",true);
+		reader.intern(tupleName + "?",true);
 
 		for(;;)
 		{
diff --git a/library/math/matrices.factor b/library/math/matrices.factor
index 925907c841..3b1bf6c4fd 100644
--- a/library/math/matrices.factor
+++ b/library/math/matrices.factor
@@ -110,7 +110,7 @@ M: col-seq nth col-seq-matrix <col> ;
     #! for being added or subtracted.
     over matrix-rows over matrix-rows = >r
     over matrix-cols over matrix-cols = r> and [
-        "Matrix dimensions do not match"
+        "Matrix dimensions do not match" throw
     ] unless ;
 
 : +dimensions ( matrix -- rows cols )
@@ -128,7 +128,7 @@ M: matrix v* ( m m -- m ) matrix+/- v* <matrix> ;
 : *check ( matrix matrix -- matrix matrix )
     over matrix-rows over matrix-cols = >r
     over matrix-cols over matrix-rows = r> and [
-        "Matrix dimensions inappropriate for composition"
+        "Matrix dimensions inappropriate for composition" throw
     ] unless ;
 
 : *dimensions ( m m -- rows cols )
diff --git a/library/syntax/parse-syntax.factor b/library/syntax/parse-syntax.factor
index 63578d7b98..f2ca81d36d 100644
--- a/library/syntax/parse-syntax.factor
+++ b/library/syntax/parse-syntax.factor
@@ -87,7 +87,11 @@ BUILTIN: f 9 ;  : f f swons ; parsing
     #! recursive words.
     CREATE drop ; parsing
 
-: FORGET: scan-word forget ; parsing
+: FORGET:
+    #! Followed by a word name. The word is removed from its
+    #! vocabulary. Note that specifying an undefined word is a
+    #! no-op.
+    scan "use" get search [ forget ] when* ; parsing
 
 : USE:
     #! Add vocabulary to search path.
diff --git a/library/tools/annotations.factor b/library/tools/annotations.factor
index 985e8c26e4..83bb9c717b 100644
--- a/library/tools/annotations.factor
+++ b/library/tools/annotations.factor
@@ -8,26 +8,23 @@ IN: words
 ! no effect of compiled calls to that word.
 USING: interpreter kernel lists prettyprint stdio strings test ;
 
-: annotate ( word quot -- ) #! Quotation: ( word def -- def )
+: annotate ( word quot -- | quot: word def -- def )
     over >r >r dup word-def r> call r> swap (define-compound) ;
     inline
 
-: (watch) >r "==> " swap word-name cat2 \ print r> cons cons ;
+: (watch) ( word def -- def )
+    >r "==> " swap word-name cat2 \ print \ .s r>
+    cons cons cons ;
 
 : watch ( word -- )
     #! Cause a message to be printed out when the word is
-    #! executed. To undo the effect of this, reload the
-    #! word with \ foo reload.
+    #! executed.
     [ (watch) ] annotate ;
 
 : break ( word -- )
     #! Cause the word to start the code walker when executed.
     [ nip [ walk ] cons ] annotate ;
 
-: dump ( word -- )
-    #! Cause the word to print the stack when executed.
-    [ nip [ .s ] swap append ] annotate ;
-
 : timer ( word -- )
     #! Print the time taken to execute the word when it's called.
     [ nip [ time ] cons ] annotate ;
diff --git a/library/unix/io.factor b/library/unix/io.factor
index 79c1510df5..146f4f6f28 100644
--- a/library/unix/io.factor
+++ b/library/unix/io.factor
@@ -1,8 +1,8 @@
-! Copyright (C) 2005 Slava Pestov.
+! Copyright (C) 2004, 2005 Slava Pestov.
 ! See http://factor.sf.net/license.txt for BSD license.
 IN: io-internals
 USING: errors generic hashtables kernel lists math namespaces
-sequences strings threads vectors ;
+sequences streams strings threads vectors ;
 
 ! These let us load the code into a CFactor instance using the
 ! old C-based I/O. They will be removed soon.
@@ -10,8 +10,39 @@ FORGET: can-read-line?
 FORGET: can-read-count?
 FORGET: can-write?
 FORGET: add-write-io-task
+FORGET: blocking-read-line
+FORGET: blocking-write
+FORGET: wait-to-read
+FORGET: wait-to-read-line
+FORGET: wait-to-write
 
+! Some general stuff
+: file-mode OCT: 0600 ;
+
+: io-error ( n -- ) 0 < [ errno strerror throw ] when ;
+
+: init-handle ( fd -- )
+    F_SETFL O_NONBLOCK 1 sys-fcntl io-error ;
+
+! Common delegate of native stream readers and writers
+TUPLE: port handle buffer error ;
+
+C: port ( handle buffer -- port )
+    [ >r <buffer> r> set-delegate ] keep
+    [ >r dup init-handle r> set-port-handle ] keep ;
+
+: buffered-port 8192 <port> ;
+
+: >port< dup port-handle swap delegate ;
+
+: pending-error ( reader -- ) port-error throw ;
+
+! Associates a port with a list of continuations waiting on the
+! port to finish I/O
 TUPLE: io-task port callbacks ;
+C: io-task ( port -- ) [ set-io-task-port ] keep ;
+
+! Multiplexer
 GENERIC: do-io-task ( task -- ? )
 GENERIC: io-task-events ( task -- events )
 
@@ -21,29 +52,62 @@ GENERIC: io-task-events ( task -- events )
 ! this with the hash-size call.
 SYMBOL: io-tasks
 
-: file-mode OCT: 0600 ;
+: init-io ( -- ) global [ <namespace> io-tasks set ] bind ;
 
-: io-error ( n -- ) 0 < [ errno strerror throw ] when ;
+: io-task-fd io-task-port port-handle ;
+
+: add-io-task ( callback task -- )
+    [ >r unit r> set-io-task-callbacks ] keep
+    dup io-task-fd io-tasks get 2dup hash [
+        "Cannot perform multiple I/O ops on the same port" throw
+    ] when set-hash ;
+
+: remove-io-task ( task -- )
+    io-task-fd io-tasks get remove-hash ;
+
+: pop-callback ( task -- callback )
+    dup io-task-callbacks uncons dup [
+        rot set-io-task-callbacks
+    ] [
+        drop swap remove-io-task
+    ] ifte ;
+
+: handle-fd ( fd -- )
+    io-tasks get hash dup do-io-task [
+        pop-callback call
+    ] [
+        drop
+    ] ifte ;
+
+: do-io-tasks ( pollfds n -- )
+    [
+        dup pick pollfd-nth dup pollfd-revents 0 = [
+            drop
+        ] [
+            pollfd-fd handle-fd
+        ] ifte
+    ] repeat drop ;
+
+: init-pollfd ( task pollfd -- )
+    over io-task-fd over set-pollfd-fd
+    swap io-task-events swap set-pollfd-events ;
+
+: make-pollfds ( -- pollfds n )
+    io-tasks get dup hash-size [
+        swap >r <pollfd-array> 0 swap r> hash-values [
+            ( n pollfds iotask )
+            pick pick pollfd-nth init-pollfd >r 1 + r>
+        ] each nip
+    ] keep ;
+
+: io-multiplex ( -- )
+    make-pollfds 2dup 0 sys-poll drop do-io-tasks ;
+
+! Readers
 
 : open-read ( path -- fd )
     O_RDONLY file-mode sys-open dup io-error ;
 
-: open-write ( path -- fd )
-    O_WRONLY O_CREAT bitor O_TRUNC bitor file-mode sys-open
-    dup io-error ;
-
-TUPLE: port handle buffer error ;
-
-C: port ( handle buffer -- port )
-    [ >r <buffer> r> set-delegate ] keep
-    [ set-port-handle ] keep ;
-
-: buffered-port 8192 <port> ;
-
-: >port< dup port-handle swap delegate ;
-
-: pending-error ( reader -- ) port-error throw ;
-
 TUPLE: reader line ready? ;
 
 C: reader ( handle -- reader )
@@ -96,7 +160,7 @@ C: reader ( handle -- reader )
 
 TUPLE: read-line-task ;
 
-C: read-line-task ( port callbacks -- task )
+C: read-line-task ( port -- task )
     [ >r <io-task> r> set-delegate ] keep ;
 
 M: read-line-task do-io-task
@@ -127,7 +191,7 @@ M: read-line-task io-task-events ( task -- events )
 
 TUPLE: read-task count ;
 
-C: read-task ( port callbacks -- task )
+C: read-task ( port -- task )
     [ >r <io-task> r> set-delegate ] keep ;
 
 M: read-task do-io-task
@@ -152,6 +216,38 @@ M: read-task io-task-events ( task -- events )
         "reader not ready" throw
     ] ifte ;
 
+: wait-to-read-line ( port -- )
+    dup can-read-line? [
+        drop
+    ] [
+        [
+            swap <read-line-task> add-io-task io-multiplex
+        ] callcc0 drop
+    ] ifte ;
+
+M: reader stream-readln ( stream -- line )
+    dup wait-to-read-line read-fin ;
+
+: wait-to-read ( count port -- )
+    2dup can-read-count? [
+        2drop
+    ] [
+        [
+            swap <read-task> add-io-task io-multiplex
+        ] callcc0 2drop
+    ] ifte ;
+
+M: reader stream-read ( count stream -- string )
+    2dup wait-to-read read-fin ;
+
+M: reader stream-close ( stream -- ) port-handle sys-close ;
+
+! Writers
+
+: open-write ( path -- fd )
+    O_WRONLY O_CREAT bitor O_TRUNC bitor file-mode sys-open
+    dup io-error ;
+
 TUPLE: writer ;
 
 C: writer ( fd -- writer )
@@ -173,7 +269,7 @@ C: writer ( fd -- writer )
 
 TUPLE: write-task ;
 
-C: write-task ( port callbacks -- task )
+C: write-task ( port -- task )
     [ >r <io-task> r> set-delegate ] keep ;
 
 M: write-task do-io-task
@@ -187,8 +283,41 @@ M: write-task io-task-events ( task -- events )
     drop write-events ;
 
 : write-fin ( str writer -- )
-    dup pending-error
-    >r dup string? [ ch>string ] unless r> >buffer ;
+    dup pending-error >buffer ;
+
+: add-write-io-task ( callback task -- )
+    dup io-task-fd io-tasks get hash [
+        dup write-task? [
+            [
+                nip io-task-callbacks cons
+            ] keep set-io-task-callbacks
+        ] [
+            add-io-task
+        ] ifte
+    ] [
+        add-io-task
+    ] ifte* ;
+
+M: writer stream-flush ( stream -- )
+    [
+        swap <write-task> add-write-io-task io-multiplex
+    ] callcc0 drop ;
+
+M: writer stream-auto-flush ( stream -- ) drop ;
+
+: wait-to-write ( len port -- )
+    tuck can-write? [ drop ] [ stream-flush ] ifte ;
+
+: blocking-write ( str writer -- )
+    over length over wait-to-write write-fin ;
+
+M: writer stream-write-attr ( string style writer -- )
+    nip >r dup string? [ ch>string ] unless r> blocking-write ;
+
+M: writer stream-close ( stream -- )
+    dup stream-flush port-handle sys-close ;
+
+! Copying from a reader to a writer
 
 : can-copy? ( from -- ? )
     dup eof? [ read-step ] [ drop t ] ifte ;
@@ -207,69 +336,3 @@ M: write-task io-task-events ( task -- events )
     ] [
         2drop f
     ] ifte ;
-
-: io-task-fd io-task-port port-handle ;
-
-: add-io-task ( task -- )
-    dup io-task-fd io-tasks get 2dup hash [
-        "Cannot perform multiple I/O ops on the same port" throw
-    ] when set-hash ;
-
-: add-write-io-task ( task -- )
-    dup io-task-fd io-tasks get hash [
-        dup write-task? [
-            [
-                >r io-task-callbacks r> io-task-callbacks append
-            ] keep set-io-task-callbacks
-        ] [
-            add-io-task
-        ] ifte
-    ] [
-        add-io-task
-    ] ifte* ;
-
-: remove-io-task ( task -- )
-    io-task-fd io-tasks get remove-hash ;
-
-: pop-callback ( task -- callback )
-    dup io-task-callbacks uncons dup [
-        rot set-io-task-callbacks
-    ] [
-        drop swap remove-io-task
-    ] ifte ;
-
-: handle-fd ( fd -- )
-    io-tasks get hash dup do-io-task [
-        pop-callback call
-    ] [
-        drop
-    ] ifte ;
-
-: do-io-tasks ( pollfds n -- )
-    [
-        dup pick pollfd-nth dup pollfd-revents 0 = [
-            drop
-        ] [
-            pollfd-fd handle-fd
-        ] ifte
-    ] repeat drop ;
-
-: init-pollfd ( task pollfd -- )
-    over io-task-fd over set-pollfd-fd
-    swap io-task-events swap set-pollfd-events ;
-
-: make-pollfds ( -- pollfds n )
-    io-tasks get dup hash-size [
-        <pollfd-array> swap hash-values [
-            dup io-task-fd pick pollfd-nth init-pollfd
-        ] each
-    ] keep ;
-
-: io-multiplexer ( -- )
-    make-pollfds dupd 0 sys-poll do-io-tasks ;
-
-: io-loop ( -- ) io-multiplexer yield io-loop ;
-
-: init-io ( -- )
-    global [ <namespace> io-tasks set ] bind
-    [ io-loop ] in-thread ;
diff --git a/library/unix/syscalls.factor b/library/unix/syscalls.factor
index 8979bbb8f4..5d0ee4846d 100644
--- a/library/unix/syscalls.factor
+++ b/library/unix/syscalls.factor
@@ -80,6 +80,12 @@ END-STRUCT
 : sys-close ( fd -- )
     "void" "libc" "close" [ "int" ] alien-invoke ;
 
+: F_SETFL 4 ; ! set file status flags
+: O_NONBLOCK 4 ; ! no delay
+
+: sys-fcntl ( fd cmd key value -- n )
+    "int" "libc" "fcntl" [ "int" "int" "int" "int" ] alien-invoke ;
+
 : sys-read ( fd buf nbytes -- n )
     "ssize_t" "libc" "read" [ "int" "ulong" "size_t" ] alien-invoke ;
 
diff --git a/native/alien.c b/native/alien.c
index 6d4ac5d94e..4a9dc29180 100644
--- a/native/alien.c
+++ b/native/alien.c
@@ -15,7 +15,7 @@ INLINE void* alien_offset(CELL object)
 		return alien->ptr;
 	case BYTE_ARRAY_TYPE:
 		array = untag_byte_array_fast(object);
-		return array + sizeof(F_ARRAY);
+		return array + 1;
 	case DISPLACED_ALIEN_TYPE:
 		d = untag_displaced_alien_fast(object);
 		return alien_offset(d->alien) + d->displacement;