diff --git a/extra/modern/modern-tests.factor b/extra/modern/modern-tests.factor
index 86c1cc7111..b373988418 100644
--- a/extra/modern/modern-tests.factor
+++ b/extra/modern/modern-tests.factor
@@ -256,3 +256,7 @@ IN: modern.tests
 { t } [ "foo[[ ]]" [ rewrite-string-exact ] keep sequence= ] unit-test
 { t } [ "foo[11[ ]11]" [ rewrite-string-exact ] keep sequence= ] unit-test
 { t } [ "foo[123[ ]123]" [ rewrite-string-exact ] keep sequence= ] unit-test
+
+
+{ } [ "[1,b)" string>literals drop ] unit-test
+{ } [ "[1,b]" string>literals drop ] unit-test
\ No newline at end of file
diff --git a/extra/modern/modern.factor b/extra/modern/modern.factor
index f2e8cbd572..a33f9b366e 100644
--- a/extra/modern/modern.factor
+++ b/extra/modern/modern.factor
@@ -13,11 +13,17 @@ ERROR: long-opening-mismatch tag open string n ch ;
 ERROR: unexpected-terminator string n slice ; ! ] } ) ;
 ERROR: compound-syntax-disallowed seq n obj ;
 
-ERROR: expected-digits-only str n got ;
+ERROR: expected-digits-only-or-equals-only str n got ;
 ! Allow [00[ ]00] etc
-: check-digits ( str n got -- str n digits )
-    dup but-last [ digit? ] all?
-    [ >string but-last expected-digits-only ] unless ;
+: container-expander-char? ( ch -- ? )
+    { [ digit? ] [ char: = = ] } 1|| ; inline
+
+: check-container-expander ( str n got -- str n digits )
+    dup but-last {
+        [ [ digit? ] all? ]
+        [ [ char: = = ] all? ]
+    } 1||
+    [ >string but-last expected-digits-only-or-equals-only ] unless ;
 
 ! (( )) [[ ]] {{ }}
 MACRO:: read-double-matched ( $open-ch -- quot: ( string n tag ch -- string n' seq ) )
@@ -27,10 +33,10 @@ MACRO:: read-double-matched ( $open-ch -- quot: ( string n tag ch -- string n' s
     :> ( $openstr2 $openstr1 $closestr2 ) ! "[[" "[" "]]"
     |[ $string $n $tag! $ch |
         $ch {
-            { [ dup digit? ] [
+            { [ dup container-expander-char? ] [
                 drop $tag 1 cut-slice* drop $tag! ! XXX: $tag of (=( is ( here, fix it (??)
-                $string $n $openstr1 slice-until-include [
-                    check-digits  ! 000] ok,  00a] bad
+                $string $n $openstr1 slice-until-token-include [
+                    check-container-expander  ! 000] ok, =] ok,  00=] bad
                     -1 modify-from
                 ] dip :> ( $string' $n' $opening $ch )
                 $ch $open-ch = [ $tag $openstr2 $string $n $ch long-opening-mismatch ] unless
@@ -106,12 +112,27 @@ DEFER: lex-factor-nested
 
 DEFER: lex-factor-fallthrough
 MACRO:: read-matched ( $ch -- quot: ( string n tag -- string n' slice' ) )
-    { 48 49 50 51 52 53 54 55 56 57 $ch }
-    $ch matching-delimiter 1string :> ( $openstreq $closestr1 ) ! digits ]
+    {
+        char: 0 char: 1 char: 2 char: 3 char: 4 char: 5
+        char: 6 char: 7 char: 8 char: 9 $ch char: =
+    } :> $openstr-chars
+
+    $ch matching-delimiter 1string :> $closestr1
     |[ $string $n $tag |
         $string $n $tag
         2over nth-check-eof {
-            { [ dup $openstreq member? ] [ $ch read-double-matched ] } ! (=( or ((
+            { [
+                dup {
+                    [ $openstr-chars member? ]
+                    [
+                        ! check that opening is good form
+                        drop
+                        $string $n [
+                            { [ $ch = ] [ blank? ] } 1||
+                        ] t slice-until 3nip $ch =
+                    ]
+                } 1&&
+            ] [ $ch read-double-matched ] } ! (=( or ((
             { [ dup blank? ] [
                 drop dup '[ _ matching-delimiter-string $closestr1 2array members lex-until ] dip
                 swap unclip-last 3array $ch <matched>
@@ -128,7 +149,7 @@ MACRO:: read-matched ( $ch -- quot: ( string n tag -- string n' slice' ) )
 : read-paren ( string n slice -- string n' obj ) char: \( read-matched ;
 : read-string-payload ( string n -- string n' )
     dup [
-        { char: \\ char: \" } slice-until-include {
+        { char: \\ char: \" } slice-until-token-include {
             { f [ drop ] }
             { char: \" [ drop ] }
             { char: \\ [ drop next-char-from drop read-string-payload ] }
@@ -421,7 +442,7 @@ DEFER: lex-factor-top*
         { char: \" [ read-string ] }
         { char: \! [ read-exclamation ] }
         { char: > [
-            [ [ char: > = not ] slice-until-exclude drop ] dip merge-slices
+            [ [ char: > = not ] f slice-until drop ] dip merge-slices
             dup section-close-form? [
                 [ slice-til-whitespace drop ] dip ?span-slices
             ] unless
diff --git a/extra/modern/slices/slices-tests.factor b/extra/modern/slices/slices-tests.factor
index 0d53af38af..4551c2d567 100644
--- a/extra/modern/slices/slices-tests.factor
+++ b/extra/modern/slices/slices-tests.factor
@@ -27,10 +27,10 @@ IN: modern.slices.tests
     "foo:" 3 slice-til-whitespace
 ] unit-test
 
-{ "foo " f T{ slice f 0 4 "foo " } f } [
-    "foo " 0 [ blank? ] slice-until-include
+{ "foo " 4 T{ slice f 0 4 "foo " } 32 } [
+    "foo " 0 [ blank? ] t slice-until
 ] unit-test
 
 { "foo " 3 T{ slice f 0 3 "foo " } 32 } [
-    "foo " 0 [ blank? ] slice-until-exclude
+    "foo " 0 [ blank? ] f slice-until
 ] unit-test
diff --git a/extra/modern/slices/slices.factor b/extra/modern/slices/slices.factor
index 7129d12760..89fdeb05b7 100644
--- a/extra/modern/slices/slices.factor
+++ b/extra/modern/slices/slices.factor
@@ -1,7 +1,8 @@
 ! Copyright (C) 2016 Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: accessors assocs fry kernel locals math sequences
-sequences.deep sequences.extras strings unicode sequences.private ;
+sequences.deep sequences.extras strings unicode sequences.private
+shuffle ;
 IN: modern.slices
 
 ERROR: unexpected-eof string n expected ;
@@ -53,38 +54,39 @@ ERROR: unexpected-eof string n expected ;
 : find-from*' ( ... seq n quot: ( ... elt -- ... ? ) -- ... i elt ? )
     swapd find-from* ; inline
 
-: slice-until-exclude ( string n quot -- string n' slice/f ch/f )
-    over [
-        [ drop ]
-        [ find-from' ] 3bi ! ( string n n' ch )
-        [ drop nip ]
-        [ [ rot ?<slice> ] dip ] 4bi
+: slice-until ( string n quot include? -- string n' slice/f ch/f )
+    pick [
+        '[
+            [ drop ]
+            [ find-from' _ [ [ ?1+ ] dip ] when ] 3bi ! ( string n n' ch )
+
+            [ drop nip ]
+            [ [ rot ?<slice> ] dip ] 4bi
+        ] call
     ] [
-        drop f f
+        2drop f f
     ] if ; inline
 
-: slice-until-include ( string n tokens -- string n' slice/f ch/f )
-    over [
-        '[ _ member? ]
-        [ drop ]
-        [ find-from' [ ?1+ ] dip ] 3bi ! ( string n n' ch )
-        [ drop nip ]
-        [ [ rot ?<slice> ] dip ] 4bi
-    ] [
-        drop f f
-    ] if ; inline
+: slice-until-token-exclude ( string n tokens -- string n' slice/f ch/f )
+    '[ _ member? ] f slice-until ; inline
+
+: slice-until-token-include ( string n tokens -- string n' slice/f ch/f )
+    '[ _ member? ] t slice-until ; inline
+
+: peek-until ( string n quot include? -- string n slice/f ch/f )
+    '[ _ slice-until 2nipd ] 2keepd 2swap ; inline
 
 : slice-til-whitespace ( string n -- string n' slice/f ch/f )
-    [ "\s\r\n" member? ] slice-until-exclude ; inline
+    [ "\s\r\n" member? ] f slice-until ; inline
 
 : slice-til-not-whitespace ( string n -- string n' slice/f ch/f )
-    [ "\s\r\n" member? not ] slice-until-exclude ; inline
+    [ "\s\r\n" member? not ] f slice-until ; inline
 
 : skip-whitespace ( string n/f -- string n'/f )
     slice-til-not-whitespace 2drop ;
 
 : slice-til-eol ( string n -- string n' slice/f ch/f )
-    [ "\r\n" member? ] slice-until-exclude ; inline
+    [ "\r\n" member? ] f slice-until ; inline
 
 : merge-slice-til-whitespace ( string n slice -- string n' slice' )
     over [