diff --git a/basis/regexp/regexp.factor b/basis/regexp/regexp.factor
index aa56543855..3d616e9556 100644
--- a/basis/regexp/regexp.factor
+++ b/basis/regexp/regexp.factor
@@ -3,7 +3,8 @@
 USING: accessors combinators kernel kernel.private math sequences
 sequences.private strings sets assocs make lexer namespaces parser
 arrays fry locals regexp.parser splitting sorting regexp.ast
-regexp.negation regexp.compiler compiler.units words math.ranges ;
+regexp.negation regexp.compiler compiler.units words math.ranges
+multiline ;
 IN: regexp
 
 TUPLE: regexp
@@ -216,7 +217,27 @@ PRIVATE>
 
 PRIVATE>
 
+: parse-optioned-regexp ( accum string -- accum )
+    parse-multiline-string lexer get
+    parse-noblank-token <optioned-regexp> compile-next-match
+    suffix! ;
+
 SYNTAX: R/ parse-regexp ;
+SYNTAX: \R[[ "]]" parse-optioned-regexp ;
+SYNTAX: \R[=[ "]=]" parse-optioned-regexp ;
+SYNTAX: \R[==[ "]==]" parse-optioned-regexp ;
+SYNTAX: \R[===[ "]===]" parse-optioned-regexp ;
+SYNTAX: \R[====[ "]====]" parse-optioned-regexp ;
+SYNTAX: \R(( "))" parse-optioned-regexp ;
+SYNTAX: \R(=( ")=)" parse-optioned-regexp ;
+SYNTAX: \R(==( ")==)" parse-optioned-regexp ;
+SYNTAX: \R(===( ")===)" parse-optioned-regexp ;
+SYNTAX: \R(====( ")====)" parse-optioned-regexp ;
+SYNTAX: \R{{ "}}" parse-optioned-regexp ;
+SYNTAX: \R{={ "}=}" parse-optioned-regexp ;
+SYNTAX: \R{=={ "}==}" parse-optioned-regexp ;
+SYNTAX: \R{==={ "}===}" parse-optioned-regexp ;
+SYNTAX: \R{===={ "}====}" parse-optioned-regexp ;
 
 USE: vocabs.loader
 
diff --git a/extra/yaml/conversion/conversion.factor b/extra/yaml/conversion/conversion.factor
index 519dd0a91d..5a1b7fc66e 100644
--- a/extra/yaml/conversion/conversion.factor
+++ b/extra/yaml/conversion/conversion.factor
@@ -15,16 +15,16 @@ CONSTANT: YAML_VALUE_TAG "tag:yaml.org,2002:value"
 ! http://www.yaml.org/spec/1.2/spec.html
 ! 10.3. Core Schema
 
-CONSTANT: re-null R/ null|Null|NULL|~/
-CONSTANT: re-empty R/ /
-CONSTANT: re-bool R/ true|True|TRUE|false|False|FALSE/
-CONSTANT: re-int10 R/ [-+]?[0-9]+/
-CONSTANT: re-int8 R/ 0o[0-7]+/
-CONSTANT: re-int16 R/ 0x[0-9a-fA-F]+/
-CONSTANT: re-number R/ [-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?/
-CONSTANT: re-infinity R/ [-+]?\.(inf|Inf|INF)/
-CONSTANT: re-nan R/ \.(nan|NaN|NAN)/
-CONSTANT: re-timestamp R/ [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]|[0-9][0-9][0-9][0-9]-[0-9][0-9]?-[0-9][0-9]?([Tt]|[ \t]+)[0-9][0-9]?:[0-9][0-9]:[0-9][0-9](\.[0-9]*)?([ \t]*(Z|[-+][0-9][0-9]?(:[0-9][0-9])?))?/
+CONSTANT: re-null R[[ null|Null|NULL|~]]
+CONSTANT: re-empty R[[ ]]
+CONSTANT: re-bool R[[ true|True|TRUE|false|False|FALSE]]
+CONSTANT: re-int10 R[[ [-+]?[0-9]+]]
+CONSTANT: re-int8 R[[ 0o[0-7]+]]
+CONSTANT: re-int16 R[[ 0x[0-9a-fA-F]+]]
+CONSTANT: re-number R[[ [-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?]]
+CONSTANT: re-infinity R[[ [-+]?\.(inf|Inf|INF)]]
+CONSTANT: re-nan R[[ \.(nan|NaN|NAN)]]
+CONSTANT: re-timestamp R[[ [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]|[0-9][0-9][0-9][0-9]-[0-9][0-9]?-[0-9][0-9]?([Tt]|[ \t]+)[0-9][0-9]?:[0-9][0-9]:[0-9][0-9](\.[0-9]*)?([ \t]*(Z|[-+][0-9][0-9]?(:[0-9][0-9])?))?]]
 
 : resolve-normal-plain-scalar ( str -- tag )
     {
@@ -41,8 +41,8 @@ CONSTANT: re-timestamp R/ [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]|[0-9][0-9][
         [ drop YAML_STR_TAG ]
     } cond-case ;
 
-CONSTANT: re-merge R/ <</
-CONSTANT: re-value R/ =/
+CONSTANT: re-merge R[[ <<]]
+CONSTANT: re-value R[[ =]]
 : (resolve-mapping-key-plain-scalar) ( str -- tag )
     {
         { [ re-merge matches? ] [ YAML_MERGE_TAG ] }
@@ -87,7 +87,7 @@ CONSTANT: YAML_OMAP_TAG "tag:yaml.org,2002:omap"
 CONSTANT: YAML_PAIRS_TAG "tag:yaml.org,2002:pairs"
 CONSTANT: YAML_SET_TAG "tag:yaml.org,2002:set"
 
-: construct-bool ( str -- ? ) R/ true|True|TRUE/ matches? ;
+: construct-bool ( str -- ? ) R[[ true|True|TRUE]] matches? ;
 
 : construct-int ( str -- n ) string>number ;
 
@@ -107,14 +107,14 @@ CONSTANT: YAML_SET_TAG "tag:yaml.org,2002:set"
 ! - months, days and hours on 1 digit
 ! preprocess to fix this mess...
 : yaml>rfc3339 ( str -- str' )
-    R/ -[0-9][^0-9]/ [ [ char: 0 1 ] dip insert-nth ] re-replace-with
-    R/ -[0-9][^0-9]/ [ [ char: 0 1 ] dip insert-nth ] re-replace-with
-    R/ [^0-9][0-9]:/ [ [ char: 0 1 ] dip insert-nth ] re-replace-with
-    R/ [ \t]+/ " " re-replace
+    R[=[ -[0-9][^0-9]]=] [ [ char: 0 1 ] dip insert-nth ] re-replace-with
+    R[=[ -[0-9][^0-9]]=] [ [ char: 0 1 ] dip insert-nth ] re-replace-with
+    R[=[ [^0-9][0-9]:]=] [ [ char: 0 1 ] dip insert-nth ] re-replace-with
+    R[=[ [ \t]+]=] " " re-replace
     char: \: over index cut char: space swap remove append ;
 
 : construct-timestamp ( obj -- obj' )
-    dup R/ [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]/ matches?
+    dup R[=[ [0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]]=] matches?
     [ ymd>timestamp ] [ yaml>rfc3339 rfc3339>timestamp ] if ;
 
 TUPLE: yaml-merge ;