diff --git a/runtime/syntax/diff.vim b/runtime/syntax/diff.vim
index ac43d66..408556a 100644
--- a/runtime/syntax/diff.vim
+++ b/runtime/syntax/diff.vim
@@ -2,7 +2,7 @@
 " Language:	Diff (context or unified)
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
 "               Translations by Jakson Alves de Aquino.
-" Last Change:	2020 Dec 07
+" Last Change:	2020 Dec 30
 
 " Quit when a (custom) syntax file was already loaded
 if exists("b:current_syntax")
@@ -348,11 +348,16 @@
 syn match diffFile	"^diff\>.*"
 syn match diffFile	"^Index: .*"
 syn match diffFile	"^==== .*"
-" Old style diff uses *** for old and --- for new.
-" Unified diff uses --- for old and +++ for new; names are wrong but it works.
-syn match diffOldFile	"^+++ .*"
-syn match diffOldFile	"^\*\*\* .*"
-syn match diffNewFile	"^--- .*"
+
+if search('^@@ -\S\+ +\S\+ @@', 'nw', '', 100)
+  " unified
+  syn match diffOldFile	"^--- .*"
+  syn match diffNewFile	"^+++ .*"
+else
+  " context / old style
+  syn match diffOldFile	"^\*\*\* .*"
+  syn match diffNewFile	"^--- .*"
+endif
 
 " Used by git
 syn match diffIndexLine	"^index \x\x\x\x.*"
diff --git a/runtime/syntax/dune.vim b/runtime/syntax/dune.vim
index f901813..b425405 100644
--- a/runtime/syntax/dune.vim
+++ b/runtime/syntax/dune.vim
@@ -1,7 +1,8 @@
+" Vim syntax file
 " Language:    Dune buildsystem
 " Maintainer:  Markus Mottl        <markus.mottl@gmail.com>
 "              Anton Kochkov       <anton.kochkov@gmail.com>
-" URL:         https://github.com/rgrinberg/vim-ocaml
+" URL:         https://github.com/ocaml/vim-ocaml
 " Last Change:
 "              2019 Feb 27 - Add newer keywords to the syntax (Simon Cruanes)
 "              2018 May 8 - Check current_syntax (Kawahara Satoru)
@@ -28,7 +29,7 @@
 syn keyword lispKey javascript_files flags ocamlc_flags ocamlopt_flags pps staged_pps
 syn keyword lispKey library_flags c_flags c_library_flags kind package action
 syn keyword lispKey deps targets locks fallback
-syn keyword lispKey inline_tests tests names
+syn keyword lispKey inline_tests tests test names
 
 syn keyword lispAtom true false
 
diff --git a/runtime/syntax/fstab.vim b/runtime/syntax/fstab.vim
index 6b17b5a..3184887 100644
--- a/runtime/syntax/fstab.vim
+++ b/runtime/syntax/fstab.vim
@@ -1,8 +1,8 @@
 " Vim syntax file
 " Language: fstab file
 " Maintainer: Radu Dineiu <radu.dineiu@gmail.com>
-" URL: https://raw.github.com/rid9/vim-fstab/master/fstab.vim
-" Last Change: 2020 Aug 06
+" URL: https://raw.github.com/rid9/vim-fstab/master/syntax/fstab.vim
+" Last Change: 2020 Dec 30
 " Version: 1.4
 "
 " Credits:
diff --git a/runtime/syntax/gift.vim b/runtime/syntax/gift.vim
new file mode 100644
index 0000000..3f8d631
--- /dev/null
+++ b/runtime/syntax/gift.vim
@@ -0,0 +1,216 @@
+" Vim syntax file
+"
+" Language:        Moodle GIFT (General Import Format Template)
+" Maintainer:      Selim Temizer (http://selimtemizer.com)
+" Creation:        November 28, 2020
+" Latest Revision: December 21, 2020
+" Note:            The order of entities in this file is important!
+
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax")
+  finish
+endif
+
+
+setlocal conceallevel=1
+
+"-----------------------------------------------
+" GIFT entities
+
+syn match giftS        "\~"          contained                    "GIFT special characters
+syn match giftS         "="          contained
+syn match giftS         "#"          contained
+syn match giftS         "{"          contained
+syn match giftS         "}"          contained
+syn match giftS         ":"          contained
+
+syn match giftES     "\\\~"          contained  conceal  cchar=~  "GIFT escaped special characters
+syn match giftES      "\\="          contained  conceal  cchar==
+syn match giftES      "\\#"          contained  conceal  cchar=#
+syn match giftES      "\\{"          contained  conceal  cchar={
+syn match giftES      "\\}"          contained  conceal  cchar=}
+syn match giftES      "\\:"          contained  conceal  cchar=:
+
+syn match giftEN      "\\n"          contained  conceal  cchar=n  "GIFT escaped newline
+
+syn match giftFormat  "\[html]"      contained                    "GIFT formats
+syn match giftFormat  "\[plain]"     contained
+syn match giftFormat  "\[moodle]"    contained
+syn match giftFormat  "\[markdown]"  contained
+
+"--------------------------------------------------------
+" HTML entities
+
+syn match giftH            "<"       contained                    "HTML characters that might need to be handled/escaped
+syn match giftH            ">"       contained
+syn match giftH            "&"       contained
+
+syn match giftEH        "&lt;"       contained  conceal  cchar=<  "HTML escaped characters
+syn match giftEH        "&gt;"       contained  conceal  cchar=>
+syn match giftEH       "&amp;"       contained  conceal  cchar=&
+syn match giftEH      "&nbsp;"       contained  conceal  cchar=_
+
+"-------------------------------------------------------
+" Answer components: Feedback and general feedback
+
+syn match giftFB           "#\_.\{-}\(\_^\|[^\\]\)\ze\(=\|\~\|#\|####\|}\)"           contained  contains=giftF       "Feedback block
+syn match giftF         "#\zs\_.\{-}\(\_^\|[^\\]\)\ze\(=\|\~\|#\|####\|}\)"           contained  contains=@giftCEF    "Feedback
+
+syn match giftGFB          "####\_.\{-}\(\_^\|[^\\]\)\ze}"                            contained  contains=giftGF      "General feedback block
+syn match giftGF        "####\zs\_.\{-}\(\_^\|[^\\]\)\ze}"                            contained  contains=@giftCEF    "General feedback
+
+"------------------------------------------------------
+" Answer components: Other components
+
+syn keyword giftTF      T TRUE F FALSE                                                contained
+
+syn match   giftNum1    "[-+]\=[.0-9]\+"                                              contained                       "Something matching a number
+
+syn match   giftNum2    "[-+]\=[.0-9]\+\s*:\s*[-+]\=[.0-9]\+"                         contained  contains=giftNum2D   "Number with error margin
+syn match   giftNum2D                    ":"                                          contained                       "Associated delimiter
+
+syn match   giftNum3    "[-+]\=[.0-9]\+\s*\.\.\s*[-+]\=[.0-9]\+"                      contained  contains=giftNum3D   "Number as min/max range
+syn match   giftNum3D                    "\.\."                                       contained                       "Associated delimiter
+
+syn match   giftWeightB    "%-*[0-9]\{1,2}\.\?[0-9]*%"                                contained  contains=giftWeight  "Weight block
+syn match   giftWeight  "%\zs-*[0-9]\{1,2}\.\?[0-9]*\ze%"                             contained                       "Weight
+
+"-----------------------------------------------------
+" Answer choices
+
+syn match giftWrongNum  "\~\zs\_.\{-}\(\_^\|[^\\]\)\ze\(####\|}\)"                    contained  contains=@giftCEFF             "Wrong numeric choice
+syn match giftRightNum   "=\zs\_.\{-}\(\_^\|[^\\]\)\ze\(=\|\~\|####\|}\)"             contained  contains=@giftCEFFW,@giftNums  "Right numeric choice
+
+syn match giftWrong     "\~\zs\_.\{-}\(\_^\|[^\\]\)\ze\(=\|\~\|####\|}\)"             contained  contains=@giftCEFFW            "Wrong choice
+syn match giftRight      "=\zs\_.\{-}\(\ze->\|\(\_^\|[^\\]\)\ze\(=\|\~\|####\|}\)\)"  contained  contains=@giftCEFFW            "Right choice
+syn match giftMatchB                "->\_.\{-}\(\_^\|[^\\]\)\ze\(=\|\~\|####\|}\)"    contained  contains=giftMatch             "Match choice block
+syn match giftMatch              "->\zs\_.\{-}\(\_^\|[^\\]\)\ze\(=\|\~\|####\|}\)"    contained  contains=@giftCE               "Match choice
+
+"----------------------------------------------------
+" Answer
+
+syn match giftAnswer      "{\_.\{-}\(\_^\|[^\\]\)}"                                   contained  keepend  contains=@giftA     "General answer
+syn match giftAnswer      "{}"                                                        contained                               "Minimal answer
+
+syn match giftAnswerNum      "{\_[[:space:]]*#\_[^#]\_.\{-}\(\_^\|[^\\]\)}"           contained  keepend  contains=@giftANum  "Numeric answer
+syn match giftAnswerNumD  "{\zs\_[[:space:]]*#"                                       contained                               "Associated delimiter
+
+"---------------------------------------------------
+" Question
+
+" The first pattern matches the last question at the end of the file (in case there is no empty line coming after).
+" However, it slows down parsing (and especially scrolling up), therefore it is commented out.
+
+"syn match giftQuestion  "[^{[:space:]]\_.\{-}\%$"                                               keepend  contains=@giftCEF,giftAnswer,giftAnswerNum
+ syn match giftQuestion  "[^{[:space:]]\_.\{-}\n\(\s*\n\)\+"                                     keepend  contains=@giftCEF,giftAnswer,giftAnswerNum
+
+"--------------------------------------------------
+" Question name
+
+syn match giftName       "::\_.\{-}::"                                                           contains=@giftCE,giftNameD  "Question name
+syn match giftNameD      "::"                                                         contained                              "Associated delimiter
+
+"-------------------------------------------------
+" Category
+
+syn match giftCategoryB  "^\s*\$CATEGORY:.*\n\+"                                                 contains=giftCategory       "Category block
+syn match giftCategory   "^\s*\$CATEGORY:\zs.*\ze\n"                                  contained                              "Category
+
+"------------------------------------------------
+" Comments (may need to be the last entity)
+
+syn keyword giftTodo     FIXME TODO NOTE FIX XXX                                      contained
+
+syn match   giftIdB         "\[id:\(\\]\|[^][:cntrl:]]\)\+]"                          contained  contains=giftId             "Id block
+syn match   giftId       "\[id:\zs\(\\]\|[^][:cntrl:]]\)\+\ze]"                       contained                              "Id
+
+syn match   giftTagB        "\[tag:\(\\]\|[^]<>`[:cntrl:]]\)\+]"                      contained  contains=giftTag            "Tag block
+syn match   giftTag      "\[tag:\zs\(\\]\|[^]<>`[:cntrl:]]\)\+\ze]"                   contained                              "Tag
+
+syn match   giftComment  "^\s*//.*"                                                              contains=giftTodo,giftIdB,giftTagB
+
+"-----------------------------------------------
+" Clusters
+
+"Comments and entities (to be escaped)
+syn cluster giftCE    contains=giftComment,giftS,giftES,giftEN,giftH,giftEH
+
+"The above plus format
+syn cluster giftCEF   contains=@giftCE,giftFormat
+
+"The above plus feedback block
+syn cluster giftCEFF  contains=@giftCEF,giftFB
+
+"The above plus weight block
+syn cluster giftCEFFW contains=@giftCEFF,giftWeightB
+
+"Possible numerical representations
+syn cluster giftNums  contains=giftNum1,giftNum2,giftNum3
+
+"Possible contents of answers
+syn cluster giftA     contains=giftComment,giftTF,giftWrong,giftRight,giftMatchB,giftFB,giftGFB
+
+"Possible contents of numerical answers
+syn cluster giftANum  contains=giftAnswerNumD,giftComment,@giftNums,giftWrongNum,giftRightNum,giftFB,giftGFB
+
+"-----------------------------------------------
+
+let b:current_syntax = "gift"
+
+"-----------------------------------------------
+
+hi Conceal   ctermbg=NONE ctermfg=Blue       guibg=NONE guifg=Blue
+hi Feedback  ctermbg=NONE ctermfg=DarkCyan   guibg=NONE guifg=DarkCyan
+hi GFeedback ctermbg=NONE ctermfg=DarkGreen  guibg=NONE guifg=DarkGreen
+hi WeightB   ctermbg=NONE ctermfg=DarkYellow guibg=NONE guifg=DarkYellow
+
+"-----------------------------------------------
+
+hi def link giftS          Error
+hi def link giftES         Conceal
+hi def link giftEN         Conceal
+hi def link giftFormat     LineNr
+
+hi def link giftH          Error
+hi def link giftEH         Conceal
+
+hi def link giftFB         PreProc
+hi def link giftF          Feedback
+hi def link giftGFB        Title
+hi def link giftGF         GFeedback
+
+hi def link giftTF         Question
+hi def link giftNum1       Question
+hi def link giftNum2       Question
+hi def link giftNum2D      Special
+hi def link giftNum3       Question
+hi def link giftNum3D      Special
+hi def link giftWeightB    WeightB
+hi def link giftWeight     Identifier
+
+hi def link giftWrongNum   Constant
+hi def link giftRightNum   Question
+hi def link giftWrong      Constant
+hi def link giftRight      Question
+hi def link giftMatchB     ModeMsg
+hi def link giftMatch      Constant
+
+hi def link giftAnswer     MoreMsg
+hi def link giftAnswerNum  MoreMsg
+hi def link giftAnswerNumD Identifier
+
+hi def link giftQuestion   Identifier
+
+hi def link giftName       PreProc
+hi def link giftNameD      Directory
+
+hi def link giftCategoryB  LineNr
+hi def link giftCategory   Directory
+
+hi def link giftTodo       Todo
+hi def link giftIdB        LineNr
+hi def link giftId         Title
+hi def link giftTagB       LineNr
+hi def link giftTag        Constant
+hi def link giftComment    Comment
diff --git a/runtime/syntax/ocaml.vim b/runtime/syntax/ocaml.vim
index 42913f2..af3efd3 100644
--- a/runtime/syntax/ocaml.vim
+++ b/runtime/syntax/ocaml.vim
@@ -4,7 +4,7 @@
 " Maintainers:  Markus Mottl      <markus.mottl@gmail.com>
 "               Karl-Heinz Sylla  <Karl-Heinz.Sylla@gmd.de>
 "               Issac Trotts      <ijtrotts@ucdavis.edu>
-" URL:          https://github.com/rgrinberg/vim-ocaml
+" URL:          https://github.com/ocaml/vim-ocaml
 " Last Change:
 "               2018 Nov 08 - Improved highlighting of operators (Maëlan)
 "               2018 Apr 22 - Improved support for PPX (Andrey Popp)
@@ -18,14 +18,20 @@
 " can be distinguished from begin/end, which is used for indentation,
 " and folding. (David Baelde)
 
-" quit when a syntax file was already loaded
+" Quit when a syntax file was already loaded
 if exists("b:current_syntax") && b:current_syntax == "ocaml"
   finish
 endif
 
+let s:keepcpo = &cpo
+set cpo&vim
+
 " ' can be used in OCaml identifiers
 setlocal iskeyword+='
 
+" ` is part of the name of polymorphic variants
+setlocal iskeyword+=`
+
 " OCaml is case sensitive.
 syn case match
 
@@ -123,7 +129,7 @@
 syn region   ocamlModSpec matchgroup=ocamlKeyword start="\<module\>" matchgroup=ocamlModule end="\<\u\(\w\|'\)*\>" contained contains=@ocamlAllErrs,ocamlComment skipwhite skipempty nextgroup=ocamlModTRWith,ocamlMPRestr
 
 " "open"
-syn region   ocamlNone matchgroup=ocamlKeyword start="\<open\>" matchgroup=ocamlModule end="\<\u\(\w\|'\)*\( *\. *\u\(\w\|'\)*\)*\>" contains=@ocamlAllErrs,ocamlComment
+syn match   ocamlKeyword "\<open\>" skipwhite skipempty nextgroup=ocamlFullMod
 
 " "include"
 syn match    ocamlKeyword "\<include\>" skipwhite skipempty nextgroup=ocamlModParam,ocamlFullMod
@@ -225,7 +231,18 @@
 syn match    ocamlAngle        "<"
 syn match    ocamlAngle        ">"
 " Custom indexing operators:
-syn match    ocamlIndexingOp   "\.[~?!:|&$%=>@^/*+-][~?!.:|&$%<=>@^*/+-]*\(()\|\[]\|{}\)\(<-\)\?"
+syn region   ocamlIndexing matchgroup=ocamlIndexingOp
+  \ start="\.[~?!:|&$%=>@^/*+-][~?!.:|&$%<=>@^*/+-]*\_s*("
+  \ end=")\(\_s*<-\)\?"
+  \ contains=ALLBUT,@ocamlContained,ocamlParenErr
+syn region   ocamlIndexing matchgroup=ocamlIndexingOp
+  \ start="\.[~?!:|&$%=>@^/*+-][~?!.:|&$%<=>@^*/+-]*\_s*\["
+  \ end="]\(\_s*<-\)\?"
+  \ contains=ALLBUT,@ocamlContained,ocamlBrackErr
+syn region   ocamlIndexing matchgroup=ocamlIndexingOp
+  \ start="\.[~?!:|&$%=>@^/*+-][~?!.:|&$%<=>@^*/+-]*\_s*{"
+  \ end="}\(\_s*<-\)\?"
+  \ contains=ALLBUT,@ocamlContained,ocamlBraceErr
 " Extension operators (has to be declared before regular infix operators):
 syn match    ocamlExtensionOp          "#[#~?!.:|&$%<=>@^*/+-]\+"
 " Infix and prefix operators:
@@ -283,7 +300,6 @@
 syn sync match ocamlSigSync     groupthere ocamlSig     "\<end\>"
 
 " Define the default highlighting.
-" Only when an item doesn't have highlighting yet
 
 hi def link ocamlBraceErr	   Error
 hi def link ocamlBrackErr	   Error
@@ -308,14 +324,17 @@
 hi def link ocamlObject	   Include
 hi def link ocamlModule	   Include
 hi def link ocamlModParam1    Include
+hi def link ocamlGenMod       Include
 hi def link ocamlModType	   Include
 hi def link ocamlMPRestr3	   Include
 hi def link ocamlFullMod	   Include
+hi def link ocamlFuncWith	   Include
+hi def link ocamlModParam     Include
 hi def link ocamlModTypeRestr Include
 hi def link ocamlWith	   Include
 hi def link ocamlMTDef	   Include
-hi def link ocamlSigEncl    ocamlModule
-hi def link ocamlStructEncl ocamlModule
+hi def link ocamlSigEncl	   ocamlModule
+hi def link ocamlStructEncl	   ocamlModule
 
 hi def link ocamlScript	   Include
 
@@ -326,24 +345,25 @@
 hi def link ocamlMPRestr2	   Keyword
 hi def link ocamlKeyword	   Keyword
 hi def link ocamlMethod	   Include
+hi def link ocamlArrow	   Keyword
 hi def link ocamlKeyChar	   Keyword
 hi def link ocamlAnyVar	   Keyword
 hi def link ocamlTopStop	   Keyword
 
-hi def link ocamlRefAssign  ocamlKeyChar
-hi def link ocamlEqual	    ocamlKeyChar
-hi def link ocamlStar	    ocamlInfixOp
-hi def link ocamlAngle	    ocamlInfixOp
-hi def link ocamlCons	    ocamlInfixOp
+hi def link ocamlRefAssign    ocamlKeyChar
+hi def link ocamlEqual        ocamlKeyChar
+hi def link ocamlStar         ocamlInfixOp
+hi def link ocamlAngle        ocamlInfixOp
+hi def link ocamlCons         ocamlInfixOp
 
-hi def link ocamlPrefixOp	ocamlOperator
-hi def link ocamlInfixOp	ocamlOperator
-hi def link ocamlExtensionOp	ocamlOperator
-hi def link ocamlIndexingOp	ocamlOperator
+hi def link ocamlPrefixOp       ocamlOperator
+hi def link ocamlInfixOp        ocamlOperator
+hi def link ocamlExtensionOp    ocamlOperator
+hi def link ocamlIndexingOp     ocamlOperator
 
 if exists("ocaml_highlight_operators")
     hi def link ocamlInfixOpKeyword ocamlOperator
-    hi def link ocamlOperator	    Operator
+    hi def link ocamlOperator       Operator
 else
     hi def link ocamlInfixOpKeyword Keyword
 endif
@@ -353,7 +373,7 @@
 hi def link ocamlNumber	   Number
 hi def link ocamlFloat	   Float
 hi def link ocamlString	   String
-hi def link ocamlQuotedStringDelim  Identifier
+hi def link ocamlQuotedStringDelim Identifier
 
 hi def link ocamlLabel	   Identifier
 
@@ -363,8 +383,11 @@
 
 hi def link ocamlEncl	   Keyword
 
-hi def link ocamlPpxEncl    ocamlEncl
+hi def link ocamlPpxEncl       ocamlEncl
 
 let b:current_syntax = "ocaml"
 
+let &cpo = s:keepcpo
+unlet s:keepcpo
+
 " vim: ts=8
diff --git a/runtime/syntax/opam.vim b/runtime/syntax/opam.vim
new file mode 100644
index 0000000..9ac1d41
--- /dev/null
+++ b/runtime/syntax/opam.vim
@@ -0,0 +1,38 @@
+" Vim syntax file
+" Language:    OPAM - OCaml package manager
+" Maintainer:  Markus Mottl        <markus.mottl@gmail.com>
+" URL:         https://github.com/ocaml/vim-ocaml
+" Last Change:
+"              2020 Dec 31 - Added header (Markus Mottl)
+
+if exists("b:current_syntax")
+  finish
+endif
+
+" need %{vars}%
+" env: [[CAML_LD_LIBRARY_PATH = "%{lib}%/stublibs"]]
+syn keyword opamKeyword1 remove depends pin-depends depopts conflicts env packages patches version maintainer tags license homepage authors doc install author available name depexts substs synopsis description
+syn match opamKeyword2 "\v(bug-reports|post-messages|ocaml-version|opam-version|dev-repo|build-test|build-doc|build)"
+
+syn keyword opamTodo FIXME NOTE NOTES TODO XXX contained
+syn match opamComment "#.*$" contains=opamTodo,@Spell
+syn match opamOperator ">\|<\|=\|<=\|>="
+
+syn region opamInterpolate start=/%{/ end=/}%/ contained
+syn region opamString start=/"/ end=/"/ contains=opamInterpolate
+syn region opamSeq start=/\[/ end=/\]/ contains=ALLBUT,opamKeyword1,opamKeyword2
+syn region opamExp start=/{/ end=/}/ contains=ALLBUT,opamKeyword1,opamKeyword2
+
+hi link opamKeyword1 Keyword
+hi link opamKeyword2 Keyword
+
+hi link opamString String
+hi link opamExp Function
+hi link opamSeq Statement
+hi link opamOperator Operator
+hi link opamComment Comment
+hi link opamInterpolate Identifier
+
+let b:current_syntax = "opam"
+
+" vim: ts=2 sw=2
diff --git a/runtime/syntax/sexplib.vim b/runtime/syntax/sexplib.vim
new file mode 100644
index 0000000..55dd3fb
--- /dev/null
+++ b/runtime/syntax/sexplib.vim
@@ -0,0 +1,88 @@
+" Vim syntax file
+" Language:     S-expressions as used in Sexplib
+" Filenames:    *.sexp
+" Maintainers:  Markus Mottl      <markus.mottl@gmail.com>
+" URL:          https://github.com/ocaml/vim-ocaml
+" Last Change:  2020 Dec 31 - Updated header for Vim contribution (MM)
+"               2017 Apr 11 - Improved matching of negative numbers (MM)
+"               2012 Jun 20 - Fixed a block comment highlighting bug (MM)
+
+" For version 5.x: Clear all syntax items
+" For version 6.x: Quit when a syntax file was already loaded
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax") && b:current_syntax == "sexplib"
+  finish
+endif
+
+" Sexplib is case sensitive.
+syn case match
+
+" Comments
+syn keyword  sexplibTodo contained TODO FIXME XXX NOTE
+syn region   sexplibBlockComment matchgroup=sexplibComment start="#|" matchgroup=sexplibComment end="|#" contains=ALLBUT,sexplibQuotedAtom,sexplibUnquotedAtom,sexplibEncl,sexplibComment
+syn match    sexplibSexpComment "#;" skipwhite skipempty nextgroup=sexplibQuotedAtomComment,sexplibUnquotedAtomComment,sexplibListComment,sexplibComment
+syn region   sexplibQuotedAtomComment start=+"+ skip=+\\\\\|\\"+ end=+"+ contained
+syn match    sexplibUnquotedAtomComment /\([^;()" \t#|]\|#[^;()" \t|]\||[^;()" \t#]\)[^;()" \t]*/ contained
+syn region   sexplibListComment matchgroup=sexplibComment start="(" matchgroup=sexplibComment end=")" contained contains=ALLBUT,sexplibEncl,sexplibString,sexplibQuotedAtom,sexplibUnquotedAtom,sexplibTodo,sexplibNumber,sexplibFloat
+syn match    sexplibComment ";.*" contains=sexplibTodo
+
+" Atoms
+syn match    sexplibUnquotedAtom /\([^;()" \t#|]\|#[^;()" \t|]\||[^;()" \t#]\)[^;()" \t]*/
+syn region   sexplibQuotedAtom    start=+"+ skip=+\\\\\|\\"+ end=+"+
+syn match    sexplibNumber        "-\=\<\d\(_\|\d\)*[l|L|n]\?\>"
+syn match    sexplibNumber        "-\=\<0[x|X]\(\x\|_\)\+[l|L|n]\?\>"
+syn match    sexplibNumber        "-\=\<0[o|O]\(\o\|_\)\+[l|L|n]\?\>"
+syn match    sexplibNumber        "-\=\<0[b|B]\([01]\|_\)\+[l|L|n]\?\>"
+syn match    sexplibFloat         "-\=\<\d\(_\|\d\)*\.\?\(_\|\d\)*\([eE][-+]\=\d\(_\|\d\)*\)\=\>"
+
+" Lists
+syn region   sexplibEncl transparent matchgroup=sexplibEncl start="(" matchgroup=sexplibEncl end=")" contains=ALLBUT,sexplibParenErr
+
+" Errors
+syn match    sexplibUnquotedAtomErr /\([^;()" \t#|]\|#[^;()" \t|]\||[^;()" \t#]\)[^;()" \t]*\(#|\||#\)[^;()" \t]*/
+syn match    sexplibParenErr ")"
+
+" Synchronization
+syn sync minlines=50
+syn sync maxlines=500
+
+" Define the default highlighting.
+" For version 5.7 and earlier: only when not done already
+" For version 5.8 and later: only when an item doesn't have highlighting yet
+if version >= 508 || !exists("did_sexplib_syntax_inits")
+  if version < 508
+    let did_sexplib_syntax_inits = 1
+    command -nargs=+ HiLink hi link <args>
+  else
+    command -nargs=+ HiLink hi def link <args>
+  endif
+
+  HiLink sexplibParenErr            Error
+  HiLink sexplibUnquotedAtomErr     Error
+
+  HiLink sexplibComment             Comment
+  HiLink sexplibSexpComment         Comment
+  HiLink sexplibQuotedAtomComment   Include
+  HiLink sexplibUnquotedAtomComment Comment
+  HiLink sexplibBlockComment        Comment
+  HiLink sexplibListComment         Comment
+
+  HiLink sexplibBoolean             Boolean
+  HiLink sexplibCharacter           Character
+  HiLink sexplibNumber              Number
+  HiLink sexplibFloat               Float
+  HiLink sexplibUnquotedAtom        Identifier
+  HiLink sexplibEncl                Identifier
+  HiLink sexplibQuotedAtom          Keyword
+
+  HiLink sexplibTodo                Todo
+
+  HiLink sexplibEncl                Keyword
+
+  delcommand HiLink
+endif
+
+let b:current_syntax = "sexplib"
+
+" vim: ts=8
diff --git a/runtime/syntax/sml.vim b/runtime/syntax/sml.vim
index fa4524f..afff530 100644
--- a/runtime/syntax/sml.vim
+++ b/runtime/syntax/sml.vim
@@ -3,13 +3,16 @@
 " Filenames:    *.sml *.sig
 " Maintainers:  Markus Mottl            <markus.mottl@gmail.com>
 "               Fabrizio Zeno Cornelli  <zeno@filibusta.crema.unimi.it>
-" URL:          http://www.ocaml.info/vim/syntax/sml.vim
-" Last Change:  2006 Oct 23 - Fixed character highlighting bug (MM)
-"               2002 Jun 02 - Fixed small typo  (MM)
-"               2001 Nov 20 - Fixed small highlighting bug with modules (MM)
+" Last Change:  2019 Oct 01 - Only spell check strings & comments (Chuan Wei Foo)
+"               2015 Aug 31 - Fixed opening of modules (Ramana Kumar)
+"               2006 Oct 23 - Fixed character highlighting bug (MM)
 
 " quit when a syntax file was already loaded
 if exists("b:current_syntax")
+
+" Disable spell checking of syntax.
+syn spell notoplevel
+
   finish
 endif
 
@@ -52,7 +55,7 @@
 
 
 " Comments
-syn region   smlComment start="(\*" end="\*)" contains=smlComment,smlTodo
+syn region   smlComment start="(\*" end="\*)" contains=smlComment,smlTodo,@Spell
 syn keyword  smlTodo contained TODO FIXME XXX
 
 
@@ -82,7 +85,7 @@
 syn region   smlModSpec matchgroup=smlKeyword start="\<structure\>" matchgroup=smlModule end="\<\u\(\w\|'\)*\>" contained contains=@smlAllErrs,smlComment skipwhite skipempty nextgroup=smlModTRWith,smlMPRestr
 
 " "open"
-syn region   smlNone matchgroup=smlKeyword start="\<open\>" matchgroup=smlModule end="\<\u\(\w\|'\)*\(\.\u\(\w\|'\)*\)*\>" contains=@smlAllErrs,smlComment
+syn region   smlNone matchgroup=smlKeyword start="\<open\>" matchgroup=smlModule end="\<\w\(\w\|'\)*\(\.\w\(\w\|'\)*\)*\>" contains=@smlAllErrs,smlComment
 
 " "structure" - somewhat complicated stuff ;-)
 syn region   smlModule matchgroup=smlKeyword start="\<\(structure\|functor\)\>" matchgroup=smlModule end="\<\u\(\w\|'\)*\>" contains=@smlAllErrs,smlComment skipwhite skipempty nextgroup=smlPreDef
@@ -136,7 +139,7 @@
 
 syn match    smlCharacter    +#"\\""\|#"."\|#"\\\d\d\d"+
 syn match    smlCharErr      +#"\\\d\d"\|#"\\\d"+
-syn region   smlString       start=+"+ skip=+\\\\\|\\"+ end=+"+
+syn region   smlString       start=+"+ skip=+\\\\\|\\"+ end=+"+ contains=@Spell
 
 syn match    smlFunDef       "=>"
 syn match    smlRefAssign    ":="
@@ -149,9 +152,9 @@
 syn match    smlKeyChar      "\*"
 syn match    smlKeyChar      "="
 
-syn match    smlNumber	      "\<-\=\d\+\>"
-syn match    smlNumber	      "\<-\=0[x|X]\x\+\>"
-syn match    smlReal	      "\<-\=\d\+\.\d*\([eE][-+]\=\d\+\)\=[fl]\=\>"
+syn match    smlNumber        "\<-\=\d\+\>"
+syn match    smlNumber        "\<-\=0[x|X]\x\+\>"
+syn match    smlReal          "\<-\=\d\+\.\d*\([eE][-+]\=\d\+\)\=[fl]\=\>"
 
 " Synchronization
 syn sync minlines=20
@@ -167,49 +170,49 @@
 " Define the default highlighting.
 " Only when an item doesn't have highlighting yet
 
-hi def link smlBraceErr	 Error
-hi def link smlBrackErr	 Error
-hi def link smlParenErr	 Error
+hi def link smlBraceErr     Error
+hi def link smlBrackErr     Error
+hi def link smlParenErr     Error
 
-hi def link smlCommentErr	 Error
+hi def link smlCommentErr   Error
 
-hi def link smlEndErr	 Error
-hi def link smlThenErr	 Error
+hi def link smlEndErr       Error
+hi def link smlThenErr      Error
 
-hi def link smlCharErr	 Error
+hi def link smlCharErr      Error
 
-hi def link smlComment	 Comment
+hi def link smlComment      Comment
 
-hi def link smlModPath	 Include
-hi def link smlModule	 Include
-hi def link smlModParam1	 Include
-hi def link smlModType	 Include
-hi def link smlMPRestr3	 Include
-hi def link smlFullMod	 Include
+hi def link smlModPath      Include
+hi def link smlModule       Include
+hi def link smlModParam1    Include
+hi def link smlModType      Include
+hi def link smlMPRestr3     Include
+hi def link smlFullMod      Include
 hi def link smlModTypeRestr Include
-hi def link smlWith	 Include
-hi def link smlMTDef	 Include
+hi def link smlWith         Include
+hi def link smlMTDef        Include
 
 hi def link smlConstructor  Constant
 
-hi def link smlModPreRHS	 Keyword
-hi def link smlMPRestr2	 Keyword
-hi def link smlKeyword	 Keyword
-hi def link smlFunDef	 Keyword
-hi def link smlRefAssign	 Keyword
-hi def link smlKeyChar	 Keyword
-hi def link smlAnyVar	 Keyword
-hi def link smlTopStop	 Keyword
-hi def link smlOperator	 Keyword
+hi def link smlModPreRHS    Keyword
+hi def link smlMPRestr2     Keyword
+hi def link smlKeyword      Keyword
+hi def link smlFunDef       Keyword
+hi def link smlRefAssign    Keyword
+hi def link smlKeyChar      Keyword
+hi def link smlAnyVar       Keyword
+hi def link smlTopStop      Keyword
+hi def link smlOperator     Keyword
 
-hi def link smlBoolean	 Boolean
-hi def link smlCharacter	 Character
-hi def link smlNumber	 Number
-hi def link smlReal	 Float
-hi def link smlString	 String
-hi def link smlType	 Type
-hi def link smlTodo	 Todo
-hi def link smlEncl	 Keyword
+hi def link smlBoolean      Boolean
+hi def link smlCharacter    Character
+hi def link smlNumber       Number
+hi def link smlReal         Float
+hi def link smlString       String
+hi def link smlType         Type
+hi def link smlTodo         Todo
+hi def link smlEncl         Keyword
 
 
 let b:current_syntax = "sml"