.vimrc

" Vim is based on Vi. Setting `nocompatible` switches from the default
" Vi-compatibility mode and enables useful Vim functionality. This
" configuration option turns out not to be necessary for the file named
" '~/.vimrc', because Vim automatically enters nocompatible mode if that file
" is present. But we're including it here just in case this config file is
" loaded some other way (e.g. saved as `foo`, and then Vim started with
" `vim -u foo`).
set nocompatible

" Turn on syntax highlighting.
syntax on

" Disable the default Vim startup message.
set shortmess+=I

" Show line numbers.
set number

" This enables relative line numbering mode. With both number and
" relativenumber enabled, the current line shows the true line number, while
" all other lines (above and below) are numbered relative to the current line.
" This is useful because you can tell, at a glance, what count is needed to
" jump up or down to a particular line, by {count}k to go up or {count}j to go
" down.
set relativenumber

" Always show the status line at the bottom, even if you only have one window open.
set laststatus=2

" The backspace key has slightly unintuitive behavior by default. For example,
" by default, you can't backspace before the insertion point set with 'i'.
" This configuration makes backspace behave more reasonably, in that you can
" backspace over anything.
set backspace=indent,eol,start

" By default, Vim doesn't let you hide a buffer (i.e. have a buffer that isn't
" shown in any window) that has unsaved changes. This is to prevent you from "
" forgetting about unsaved changes and then quitting e.g. via `:qa!`. We find
" hidden buffers helpful enough to disable this protection. See `:help hidden`
" for more information on this.
set hidden

" This setting makes search case-insensitive when all characters in the string
" being searched are lowercase. However, the search becomes case-sensitive if
" it contains any capital letters. This makes searching more convenient.
set ignorecase
set smartcase

" Enable searching as you type, rather than waiting till you press enter.
set incsearch

" Highlight search words
set hlsearch

" Unbind some useless/annoying default key bindings.
nmap Q <Nop> " 'Q' in normal mode enters Ex mode. You almost never want this.

" Disable audible bell because it's annoying.
set noerrorbells visualbell t_vb=

" Enable mouse support.
set mouse+=a

" Preventing bad habits.
nnoremap <Left>  :echoe "Use h"<CR>
nnoremap <Right> :echoe "Use l"<CR>
nnoremap <Up>    :echoe "Use k"<CR>
nnoremap <Down>  :echoe "Use j"<CR>
inoremap <Left>  <ESC>:echoe "Use h"<CR>
inoremap <Right> <ESC>:echoe "Use l"<CR>
inoremap <Up>    <ESC>:echoe "Use k"<CR>
inoremap <Down>  <ESC>:echoe "Use j"<CR>