diff --git a/parser.go b/parser.go
index 7f97de9..6dd5326 100644
--- a/parser.go
+++ b/parser.go
@@ -45,7 +45,6 @@ type Region struct {
 }
 
 // ParseDef parses an input syntax file into a highlight Def
-// Note that ParseDef may return multiple errors
 func ParseDef(input []byte) (*Def, error) {
 	var rules map[interface{}]interface{}
 	if err := yaml.Unmarshal(input, &rules); err != nil {
diff --git a/syntax_files/go.yaml b/syntax_files/go.yaml
index e37b045..3103e60 100644
--- a/syntax_files/go.yaml
+++ b/syntax_files/go.yaml
@@ -28,7 +28,8 @@ rules:
     - comment:
         start: "/\\*"
         end: "\\*/"
-        rules: []
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
 
     - constant.string:
         start: "\""
diff --git a/syntax_files/rust.yaml b/syntax_files/rust.yaml
new file mode 100644
index 0000000..dc6d101
--- /dev/null
+++ b/syntax_files/rust.yaml
@@ -0,0 +1,46 @@
+filetype: rust
+
+detect:
+    filename: "\\.rs$"
+
+rules:
+    # function definition
+    - identifier: "fn [a-z0-9_]+"
+      # Reserved words
+    - statement: "\\b(abstract|alignof|as|become|box|break|const|continue|crate|do|else|enum|extern|false|final|fn|for|if|impl|in|let|loop|macro|match|mod|move|mut|offsetof|override|priv|pub|pure|ref|return|sizeof|static|self|struct|super|true|trait|type|typeof|unsafe|unsized|use|virtual|where|while|yield)\\b"
+      # macros
+    - special: "[a-z_]+!"
+      # Constants
+    - constant: "[A-Z][A-Z_]+"
+      # Numbers
+    - constant.number: "\\b[0-9]+\\b"
+      # Traits/Enums/Structs/Types/etc.
+    - type: "[A-Z][a-z]+"
+
+    - constant.string:
+        start: "\""
+        end: "\""
+        rules:
+            - constant.specialChar: "\\\\."
+
+    - constant.string:
+        start: "r#+\""
+        end: "\"#+"
+        rules: []
+
+    - comment:
+        start: "//"
+        end: "$"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
+
+    - comment:
+        start: "/\\*"
+        end: "\\*/"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
+
+    - special:
+        start: "#!\\["
+        end: "\\]"
+        rules: []
diff --git a/syntax_files/sh.yaml b/syntax_files/sh.yaml
new file mode 100644
index 0000000..a44ce6e
--- /dev/null
+++ b/syntax_files/sh.yaml
@@ -0,0 +1,41 @@
+filetype: shell
+
+detect:
+    filename: "(\\.sh$|\\.bash|\\.bashrc|bashrc|\\.bash_aliases|bash_aliases|\\.bash_functions|bash_functions|\\.bash_profile|bash_profile|Pkgfile|pkgmk.conf|profile|rc.conf|PKGBUILD|.ebuild\\$|APKBUILD)"
+    header: "^#!.*/(env +)?(ba)?sh( |$)"
+
+rules:
+    # Numbers
+    - constant.number: "\\b[0-9]+\\b"
+      # Conditionals and control flow
+    - statement: "\\b(case|do|done|elif|else|esac|exit|fi|for|function|if|in|local|read|return|select|shift|then|time|until|while)\\b"
+    - special: "(\\{|\\}|\\(|\\)|\\;|\\]|\\[|`|\\\\|\\$|<|>|!|=|&|\\|)"
+      # Shell commands
+    - type: "\\b(cd|echo|export|let|set|umask|unset)\\b"
+      # Common linux commands
+    - type: "\\b((g|ig)?awk|bash|dash|find|\\w{0,4}grep|kill|killall|\\w{0,4}less|make|pkill|sed|sh|tar)\\b"
+      # Coreutils commands
+    - type: "\\b(base64|basename|cat|chcon|chgrp|chmod|chown|chroot|cksum|comm|cp|csplit|cut|date|dd|df|dir|dircolors|dirname|du|env|expand|expr|factor|false|fmt|fold|head|hostid|id|install|join|link|ln|logname|ls|md5sum|mkdir|mkfifo|mknod|mktemp|mv|nice|nl|nohup|nproc|numfmt|od|paste|pathchk|pinky|pr|printenv|printf|ptx|pwd|readlink|realpath|rm|rmdir|runcon|seq|(sha1|sha224|sha256|sha384|sha512)sum|shred|shuf|sleep|sort|split|stat|stdbuf|stty|sum|sync|tac|tail|tee|test|time|timeout|touch|tr|true|truncate|tsort|tty|uname|unexpand|uniq|unlink|users|vdir|wc|who|whoami|yes)\\b"
+      # Conditional flags
+    - statement: "--[a-z-]+"
+    - statement: "\\ -[a-z]+"
+
+    - identifier: "\\$\\{?[0-9A-Z_!@#$*?-]+\\}?"
+    - identifier: "\\$\\{?[0-9A-Z_!@#$*?-]+\\}?"
+
+    - constant.string:
+        start: "\""
+        end: "\""
+        rules:
+            - constant.specialChar: "\\\\."
+
+    - constant.string:
+        start: "'"
+        end: "'"
+        rules:
+
+    - comment:
+        start: "#"
+        end: "$"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
diff --git a/syntax_files/swift.yaml b/syntax_files/swift.yaml
new file mode 100644
index 0000000..307aaf6
--- /dev/null
+++ b/syntax_files/swift.yaml
@@ -0,0 +1,49 @@
+filetype: swift
+
+detect:
+    filename: "\\.swift$"
+
+rules:
+    # Operators
+    - statement: "[.:;,+*|=!?\\%]" "<" ">" "/" "-" "&"
+
+      # Statements
+    - statement:  "(class|import|let|var|struct|enum|func|if|else|switch|case|default|for|in|internal|external|unowned|private|public|throws)\\ "
+    - statement:  "(prefix|postfix|operator|extension|lazy|get|set|self|willSet|didSet|override|super|convenience|weak|strong|mutating|return|guard)\\ "
+
+      # Keywords
+    - statement: "(print)"
+    - statement: "(init)"
+
+      # Numbers
+    - constant.number: "([0-9]+)"
+
+      # Standard Types
+    - type: "\\ ((U)?Int(8|16|32|64))"
+    - constant: "(true|false|nil)"
+    - type: "\\ (Double|String|Float|Boolean|Dictionary|Array|Int)"
+    - type: "\\ (AnyObject)"
+
+    - constant.string:
+        start: "\""
+        end: "\""
+        rules:
+            - constant.specialChar: "\\\\."
+
+    - comment:
+        start: "//"
+        end: "$"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
+
+    - comment:
+        start: "///"
+        end: "$"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"
+
+    - comment:
+        start: "/\\*\\*"
+        end: "\\*/"
+        rules:
+            - todo: "(TODO|XXX|FIXME):?"