if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'haskell') == -1
" indentation for haskell
"
" Based on idris indentation
"
" author: raichoo (raichoo@googlemail.com)
"
" Modify g:haskell_indent_if and g:haskell_indent_case to
" change indentation for `if'(default 3) and `case'(default 5).
" Example (in .vimrc):
" > let g:haskell_indent_if = 2
if exists('b:did_indent')
finish
endif
let b:did_indent = 1
if !exists('g:haskell_indent_if')
" if bool
" >>>then ...
" >>>else ...
let g:haskell_indent_if = 3
endif
if !exists('g:haskell_indent_case')
" case xs of
" >>[] -> ...
" >>(y:ys) -> ...
let g:haskell_indent_case = 2
endif
if !exists('g:haskell_indent_let')
" let x = 0 in
" >>>>x
let g:haskell_indent_let = 4
endif
if !exists('g:haskell_indent_where')
" where f :: Int -> Int
" >>>>>>f x = x
let g:haskell_indent_where = 6
endif
if !exists('g:haskell_indent_do')
" do x <- a
" >>>y <- b
let g:haskell_indent_do = 3
endif
if !exists('g:haskell_indent_in')
" let x = 1
" >in x
let g:haskell_indent_in = 1
endif
setlocal indentexpr=GetHaskellIndent()
setlocal indentkeys=!^F,o,O,0\|,0=where,0=in,0=let,0=deriving,0=->,0=\=>,<CR>,0}
function! GetHaskellIndent()
let l:prevline = getline(v:lnum - 1)
if l:prevline =~ '^\s*--'
return match(l:prevline, '\S')
endif
if l:prevline =~ '^\s*$'
return 0
endif
let l:line = getline(v:lnum)
if l:line =~ '\C^\s*\<where\>'
let l:s = match(l:prevline, '\S')
return l:s + &shiftwidth
endif
if l:line =~ '\C^\s*\<deriving\>'
let l:s = match(l:prevline, '\C\<\(newtype\|data\)\>')
if l:s >= 0
return l:s + &shiftwidth
endif
endif
if l:line =~ '\C^\s*\<let\>'
let l:s = match(l:prevline, '\C\<let\>')
if l:s != 0
return l:s
endif
endif
if l:line =~ '\C^\s*\<in\>'
let l:s = match(l:prevline, '\C\<let\>')
if l:s >= 0
return l:s + g:haskell_indent_in
elseif match(l:prevline, '=') > 0
let l:s = match(l:prevline, '\S')
return l:s - (4 - g:haskell_indent_in)
endif
endif
if l:line =~ '^\s*|'
if match(l:prevline, '^\s*data') < 0
if match(l:prevline, '^\s*|\s') >= 0
return match(l:prevline, '|')
else
return &shiftwidth
endif
endif
endif
if l:line =~ '^\s*[=-]>'
let l:s = match(l:prevline, ' :: ')
if l:s >= 0
return l:s + 1
endif
endif
if l:prevline =~ '\s\+[!#$%&*+./<>?@\\^|~-]\+\s*$'
let l:s = match(l:prevline, '\S')
if l:s > 0
return l:s + &shiftwidth
endif
endif
if l:prevline =~ '[{([][^})\]]\+$'
return match(l:prevline, '[{([]')
endif
if l:prevline =~ '\C\<let\>\s\+[^=]\+=\s*$'
return match(l:prevline, '\C\<let\>') + g:haskell_indent_let + &shiftwidth
endif
if l:prevline =~ '\C\<let\>\s\+.\+\(\<in\>\)\?\s*$'
return match(l:prevline, '\C\<let\>') + g:haskell_indent_let
endif
if l:prevline !~ '\C\<else\>'
let l:s = match(l:prevline, '\C\<if\>.*\&.*\zs\<then\>')
if l:s > 0
return l:s
endif
let l:s = match(l:prevline, '\C\<if\>')
if l:s > 0
return l:s + g:haskell_indent_if
endif
endif
if l:prevline =~ '\C\(\<where\>\|\<do\>\|=\|[{([]\)\s*$'
return match(l:prevline, '\S') + &shiftwidth
endif
if l:prevline =~ '\C\<where\>\s\+\S\+.*$'
return match(l:prevline, '\C\<where\>') + g:haskell_indent_where
endif
if l:prevline =~ '\C\<do\>\s\+\S\+.*$'
return match(l:prevline, '\C\<do\>') + g:haskell_indent_do
endif
if l:prevline =~ '\C^\s*\<data\>\s\+[^=]\+\s\+=\s\+\S\+.*$'
if l:line =~ '^\s*|'
return match(l:prevline, '=')
endif
endif
if l:prevline =~ '\C\<case\>\s\+.\+\<of\>\s*$'
return match(l:prevline, '\C\<case\>') + g:haskell_indent_case
endif
if l:prevline =~ '\C^\s*\<\data\>\s\+\S\+\s*$'
return match(l:prevline, '\C\<data\>') + &shiftwidth
endif
return match(l:prevline, '\S')
endfunction
endif
