Imported from static distribution of full Haskell mode.

Copied from
http://projects.haskell.org/haskellmode-vim/vimfiles/haskellmode-20101118.vba.

autoload/haskellmode.vim

@@ -0,0 +1,191 @@
+"
+" utility functions for haskellmode plugins
+"
+" (Claus Reinke; last modified: 22/06/2010)
+" 
+" part of haskell plugins: http://projects.haskell.org/haskellmode-vim
+" please send patches to <claus.reinke@talk21.com>
+
+
+
+" find start/extent of name/symbol under cursor;
+" return start, symbolic flag, qualifier, unqualified id
+" (this is used in both haskell_doc.vim and in GHC.vim)
+function! haskellmode#GetNameSymbol(line,col,off)
+  let name    = "[a-zA-Z0-9_']"
+  let symbol  = "[-!#$%&\*\+/<=>\?@\\^|~:.]"
+  "let [line]  = getbufline(a:buf,a:lnum)
+  let line    = a:line
+
+  " find the beginning of unqualified id or qualified id component 
+  let start   = (a:col - 1) + a:off
+  if line[start] =~ name
+    let pattern = name
+  elseif line[start] =~ symbol
+    let pattern = symbol
+  else
+    return []
+  endif
+  while start > 0 && line[start - 1] =~ pattern
+    let start -= 1
+  endwhile
+  let id    = matchstr(line[start :],pattern.'*')
+  " call confirm(id)
+
+  " expand id to left and right, to get full id
+  let idPos = id[0] == '.' ? start+2 : start+1
+  let posA  = match(line,'\<\(\([A-Z]'.name.'*\.\)\+\)\%'.idPos.'c')
+  let start = posA>-1 ? posA+1 : idPos
+  let posB  = matchend(line,'\%'.idPos.'c\(\([A-Z]'.name.'*\.\)*\)\('.name.'\+\|'.symbol.'\+\)')
+  let end   = posB>-1 ? posB : idPos
+
+  " special case: symbolic ids starting with .
+  if id[0]=='.' && posA==-1 
+    let start = idPos-1
+    let end   = posB==-1 ? start : end
+  endif
+
+  " classify full id and split into qualifier and unqualified id
+  let fullid   = line[ (start>1 ? start-1 : 0) : (end-1) ]
+  let symbolic = fullid[-1:-1] =~ symbol  " might also be incomplete qualified id ending in .
+  let qualPos  = matchend(fullid, '\([A-Z]'.name.'*\.\)\+')
+  let qualifier = qualPos>-1 ? fullid[ 0 : (qualPos-2) ] : ''
+  let unqualId  = qualPos>-1 ? fullid[ qualPos : -1 ] : fullid
+  " call confirm(start.'/'.end.'['.symbolic.']:'.qualifier.' '.unqualId)
+
+  return [start,symbolic,qualifier,unqualId]
+endfunction
+
+function! haskellmode#GatherImports()
+  let imports={0:{},1:{}}
+  let i=1
+  while i<=line('$')
+    let res = haskellmode#GatherImport(i)
+    if !empty(res)
+      let [i,import] = res
+      let prefixPat = '^import\s*\%({-#\s*SOURCE\s*#-}\)\?\(qualified\)\?\s\+'
+      let modulePat = '\([A-Z][a-zA-Z0-9_''.]*\)'
+      let asPat     = '\(\s\+as\s\+'.modulePat.'\)\?'
+      let hidingPat = '\(\s\+hiding\s*\((.*)\)\)\?'
+      let listPat   = '\(\s*\((.*)\)\)\?'
+      let importPat = prefixPat.modulePat.asPat.hidingPat.listPat ".'\s*$'
+
+      let ml = matchlist(import,importPat)
+      if ml!=[]
+        let [_,qualified,module,_,as,_,hiding,_,explicit;x] = ml
+        let what = as=='' ? module : as
+        let hidings   = split(hiding[1:-2],',')
+        let explicits = split(explicit[1:-2],',')
+        let empty = {'lines':[],'hiding':hidings,'explicit':[],'modules':[]}
+        let entry = has_key(imports[1],what) ? imports[1][what] : deepcopy(empty)
+        let imports[1][what] = haskellmode#MergeImport(deepcopy(entry),i,hidings,explicits,module)
+        if !(qualified=='qualified')
+          let imports[0][what] = haskellmode#MergeImport(deepcopy(entry),i,hidings,explicits,module)
+        endif
+      else
+        echoerr "haskellmode#GatherImports doesn't understand: ".import
+      endif
+    endif
+    let i+=1
+  endwhile
+  if !has_key(imports[1],'Prelude') 
+    let imports[0]['Prelude'] = {'lines':[],'hiding':[],'explicit':[],'modules':[]}
+    let imports[1]['Prelude'] = {'lines':[],'hiding':[],'explicit':[],'modules':[]}
+  endif
+  return imports
+endfunction
+
+function! haskellmode#ListElem(list,elem)
+  for e in a:list | if e==a:elem | return 1 | endif | endfor
+  return 0
+endfunction
+
+function! haskellmode#ListIntersect(list1,list2)
+  let l = []
+  for e in a:list1 | if index(a:list2,e)!=-1 | let l += [e] | endif | endfor
+  return l
+endfunction
+
+function! haskellmode#ListUnion(list1,list2)
+  let l = []
+  for e in a:list2 | if index(a:list1,e)==-1 | let l += [e] | endif | endfor
+  return a:list1 + l
+endfunction
+
+function! haskellmode#ListWithout(list1,list2)
+  let l = []
+  for e in a:list1 | if index(a:list2,e)==-1 | let l += [e] | endif | endfor
+  return l
+endfunction
+
+function! haskellmode#MergeImport(entry,line,hiding,explicit,module)
+  let lines    = a:entry['lines'] + [ a:line ]
+  let hiding   = a:explicit==[] ? haskellmode#ListIntersect(a:entry['hiding'], a:hiding) 
+                              \ : haskellmode#ListWithout(a:entry['hiding'],a:explicit)
+  let explicit = haskellmode#ListUnion(a:entry['explicit'], a:explicit)
+  let modules  = haskellmode#ListUnion(a:entry['modules'], [ a:module ])
+  return {'lines':lines,'hiding':hiding,'explicit':explicit,'modules':modules}
+endfunction
+
+" collect lines belonging to a single import statement;
+" return number of last line and collected import statement
+" (assume opening parenthesis, if any, is on the first line)
+function! haskellmode#GatherImport(lineno)
+  let lineno = a:lineno
+  let import = getline(lineno)
+  if !(import=~'^import\s') | return [] | endif
+  let open  = strlen(substitute(import,'[^(]','','g'))
+  let close = strlen(substitute(import,'[^)]','','g'))
+  while open!=close
+    let lineno += 1
+    let linecont = getline(lineno)
+    let open  += strlen(substitute(linecont,'[^(]','','g'))
+    let close += strlen(substitute(linecont,'[^)]','','g'))
+    let import .= linecont
+  endwhile
+  return [lineno,import]
+endfunction
+
+function! haskellmode#UrlEncode(string)
+  let pat  = '\([^[:alnum:]]\)'
+  let code = '\=printf("%%%02X",char2nr(submatch(1)))'
+  let url  = substitute(a:string,pat,code,'g')
+  return url
+endfunction
+
+" TODO: we could have buffer-local settings, at the expense of
+"       reconfiguring for every new buffer.. do we want to?
+function! haskellmode#GHC()
+  if (!exists("g:ghc") || !executable(g:ghc)) 
+    if !executable('ghc') 
+      echoerr s:scriptname.": can't find ghc. please set g:ghc, or extend $PATH"
+      return 0
+    else
+      let g:ghc = 'ghc'
+    endif
+  endif    
+  return 1
+endfunction
+
+function! haskellmode#GHC_Version()
+  if !exists("g:ghc_version")
+    let g:ghc_version = substitute(system(g:ghc . ' --numeric-version'),'\n','','')
+  endif
+  return g:ghc_version
+endfunction
+
+function! haskellmode#GHC_VersionGE(target)
+  let current = split(haskellmode#GHC_Version(), '\.' )
+  let target  = a:target
+  for i in current
+    if ((target==[]) || (i>target[0]))
+      return 1
+    elseif (i==target[0])
+      let target = target[1:]
+    else
+      return 0
+    endif
+  endfor
+  return 1
+endfunction
+