Forgot to add the syntax highlighting file for vim. That has been rectified.

psl.vim

+" Vim syntax file
+" Language: Maude-PSL
+" Maintainer: Andrew Cholewa <acholew2@illinois.edu>
+" A slightly modified version of the syntax file used for the Maude language:
+"
+" Language:      Maude <http://maude.cs.uiuc.edu/>
+" Maintainer:    Steven N. Severinghaus <sns@severinghaus.org>
+" Last Modified: 2005-02-03 " Version: 0.1
+" To install, copy (or link) this file into the ~/.vim directory 
+" and add the following to your ~/.vimrc file
+
+" au BufRead,BufNewFile *.maude set filetype=maude
+" au BufRead,BufNewFile *.kmaude set filetype=maude
+" au BufRead,BufNewFile *.k set filetype=maude
+" au BufRead,BufNewFile *.m set filetype=maude
+" au! Syntax maude source maude.vim
+" syn on
+
+
+" Quit if syntax file is already loaded
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax")
+  finish
+endif
+
+command! -nargs=+ MaudeHiLink hi def link <args>
+
+"Matches words that start with an uppercase letter.
+"Added by Andrew Cholewa
+"This is meant to allow variable names to stick out, assuming the coder
+"follows the convention of capitalizing the first character of their variable
+"names.
+"Match at least one upper-case letter followed by 0 or more digits
+"So variables are of the form T T1 T2 SPEC 
+syn match variableName      /\<\u\+\d\{-}\>/
+"Match at least one upper-case letter followed by a lower-case letter followed
+"by zero or more word characters.
+"Sorts are of the form Sortname SortName 
+syn match maudeSorts      /\<\u\l\w\{-}\>/
+"Added by Andrew Cholewa
+"This is meant to make the parenthesis stand out, which is very important
+"considering how much Maude relies on parenthesis.
+syn match parenthesis       /(/
+syn match parenthesis       /)/
+"The end result of the matching patterns above is to make the operators stick
+"out more (roughly, the non-highlighted text are the user-defined
+"operators).
+"End Material added by Andrew Cholewa
+syn keyword maudeModule     mod fmod omod endm endfm endm is endkm
+syn keyword maudeImports    protecting including extending
+syn keyword maudeSortDecl   sort sorts subsort subsorts
+syn keyword maudeStatements op ops var vars eq ceq rl crl rule macro context configuration mb cmb if fi then else
+"syn match   maudeFlags      "\[.*\]"
+syn keyword maudeCommands   reduce red rewrite rew parse frewrite frew search
+syn match   maudeComment    "\*\*\*.*"
+syn match   maudeComment    "---.*"
+syn region  maudeComment    start="/\*"  end="\*/" contains=maudeTodo,@Spell
+syn region  maudeComment    start="---("  end="---)" contains=maudeTodo,@Spell
+syn match   maudeComment    "//.*" contains=maudeTodo,@Spell
+syn match   maudeStatements    "->"
+syn match   maudeStatements    "|"
+syn match   maudeStatements    ":"
+"syn match   maudeOps        "^\s*subsorts[^<]*<"hs=e-1
+"syn match   maudeOps        "^\s*ceq[^=]*="
+syn match   maudeOps        "="
+syn match   maudeOps        "\.\s*$"
+
+"syn keyword maudeSorts      K KResult KLabel KResultLabel List Bag Set Map
+"syn keyword maudeSorts      NeList NeMap NeBag NeSet
+"syn keyword maudeSorts      KProper KProperLabel NeKProperList
+"syn keyword maudeSorts      CellLabel ListItem BagItem SetItem MapItem
+
+syn keyword maudeAttrs      assoc comm idem iter id left-id right-id strat memo
+syn keyword maudeAttrs      prec gather format ctor config object msg frozen
+syn keyword maudeAttrs      poly special label metadata owise nonexec
+syn keyword maudeAttrs      seqstrict strict structural hybrid nondet bidirectional large
+syn keyword maudeAttrs      latex
+
+syn match maudeStatements   "_" 
+syn match maudeStatements   "?"
+syn match maudeStatements   "\.\.\." 
+
+"syn keyword maudeLiteral    Bool Int Float Nat Qid Id
+"syn keyword maudeLiteral    Zero NzNat NzInt NzRat Rat FiniteFloat
+"syn keyword maudeLiteral    String Char FindResult DecFloat
+syn keyword maudeLiteral    andBool orBool xorBool notBool impliesBool
+"syn keyword maudeLiteral    sNat
+syn keyword maudeLiteral    true false
+syn match   maudeLiteral    "\<\(0[0-7]*\|0[xX]\x\+\|\d\+\)[lL]\=\>"
+syn match   maudeLiteral    "\(\<\d\+\.\d*\|\.\d\+\)\([eE][-+]\=\d\+\)\=[fFdD]\="
+
+syn keyword maudeTodo       contained TODO FIXME XXX NOTE BUG
+
+syn region  maudeString     start=+"+ end=+"+ contains=@Spell
+
+MaudeHiLink maudeModule     PreProc
+MaudeHiLink maudeImports    PreProc
+MaudeHiLink maudeAttrs      Comment
+MaudeHiLink maudeStatements Keyword
+MaudeHiLink maudeModules    String
+MaudeHiLink maudeComment    Comment
+MaudeHiLink maudeSortDecl   Keyword
+MaudeHiLink maudeOps        Special
+MaudeHiLink maudeCommands   Special
+MaudeHiLink maudeFlags      Comment
+MaudeHiLink maudeSorts      PreProc
+MaudeHiLink maudeLiteral    String
+MaudeHiLink maudeTodo       Todo
+MaudeHiLink maudeString     String
+"Added by Andrew Cholewa
+MaudeHiLink variableName    Identifier
+MaudeHiLink parenthesis     Comment
+"hi def     maudeMisc       term=bold cterm=bold gui=bold
+
+delcommand MaudeHiLink
+  
+let b:current_syntax = "maude"
+
+"EOF vim: tw=78:ft=vim:ts=8