wrap.vim

function! s:toggle_wrap()
  if &wrap
    set nowrap

    nnoremap <buffer> j j
    nnoremap <buffer> k k
    nnoremap <buffer> 0 0
    nnoremap <buffer> ^ ^
    nnoremap <buffer> $ $

    nnoremap <buffer> gj gj
    nnoremap <buffer> gk gk
    nnoremap <buffer> g0 g0
    nnoremap <buffer> g^ g^
    nnoremap <buffer> g$ g$
  else
    set wrap

    nnoremap <buffer> j gj
    nnoremap <buffer> k gk
    nnoremap <buffer> 0 g0
    nnoremap <buffer> ^ g^
    nnoremap <buffer> $ g$

    nnoremap <buffer> gj j
    nnoremap <buffer> gk k
    nnoremap <buffer> g0 0
    nnoremap <buffer> g^ ^
    nnoremap <buffer> g$ $
  endif
endfunction

set nowrap " by default

nnoremap <silent> <Tab> :<C-u>call <SID>toggle_wrap()<CR>