Add configuration for vim

- Add ~/.config/vim/vimrc
  + Configure basic stuff
  + Activate spell checks
  + Activate syntax highlighting and ruler
  + Show whitespace characters
  + Add various snippets for mouse handling,
    toggling line numbers, and search
  + Set `vim`-related directories inside
   ~/.config/vim and ~/.local/state/vim
- Integrate extra settings for Python files
  in ~/.config/vim/after/ftplugin/python.vim
- Add `vim` artifacts in ~/.config/git/ignore

.config/git/ignore

@@ -4,3 +4,24 @@
 *.orig
 *.temp
 *.tmp
+
+# Vim
+# Source: https://github.com/github/gitignore/blob/main/Global/Vim.gitignore
+#
+# Swap
+[._]*.s[a-v][a-z]
+!*.svg
+[._]*.sw[a-p]
+[._]s[a-rt-v][a-z]
+[._]ss[a-gi-z]
+[._]sw[a-p]
+# Session
+Session.vim
+Sessionx.vim
+# Temporary
+.netrwhist
+*~
+# Auto-generated tag files
+tags
+# Persistent undo
+[._]*.un~

.config/shell/env

@@ -22,11 +22,14 @@ export DOTFILES_DIR="$XDG_DATA_HOME/dotfiles"  # also set in ~/.local/bin/instal
 
 # Generic shell configs
 
+export EDITOR=vim
 export GPG_TTY=$(tty)
 export PAGER="less --chop-long-lines --ignore-case --LONG-PROMPT --no-init --status-column --quit-if-one-screen"
 export TZ="Europe/Berlin"
+export VISUAL=$EDITOR
 
 
 # Move common tools' config and cache files into XDG directories
 
 export LESSHISTFILE="$XDG_STATE_HOME/less/history"
+export VIMINIT='let $MYVIMRC="'"$XDG_CONFIG_HOME"'/vim/vimrc" | source $MYVIMRC'

.config/vim/after/ftplugin/python.vim

@@ -0,0 +1,91 @@
+" Set the search path to the folder of the current file and its sub-folders
+setlocal path=.,**
+
+" Exclude Python's compiled files from searches
+setlocal wildignore=*/__pycache__/*,*.pyc
+
+
+" Resolve Python imports to files,
+" so that `gf` jumps to the module under the cursor
+"
+" Examples, with the cursor on the marked word:
+"  - `from lalib.elements import galois` => lalib/elements/galois.py
+"  - `from lalib.elements import ...`    => lalib/elements/__init__.py
+"  - `import lalib.config`               => lalib/config.py
+"
+if !exists('*s:PyGoToFile')
+
+    " Build the dotted module path for the word under the cursor
+    function! s:PyModuleUnderCursor()
+        let l:word = expand('<cword>')
+        let l:from = matchstr(getline('.'), '^\s*from\s\+\zs[A-Za-z0-9_.]\+')
+        let l:imp  = matchstr(getline('.'), '^\s*import\s\+\zs[A-Za-z0-9_.]\+')
+        let l:base = !empty(l:from) ? l:from : l:imp
+        if empty(l:base)
+            return ''
+        endif
+        let l:parts = split(l:base, '\.')
+        let l:idx = index(l:parts, l:word)
+        if l:idx >= 0  " Cursor within the dotted prefix => Truncate there
+            return join(l:parts[0:l:idx], '/')
+        elseif !empty(l:from)  " Cursor on an imported name => Append it
+            return join(l:parts, '/') . '/' . l:word
+        endif
+        return ''
+    endfunction
+
+    function! s:PyFindFile(mod)
+        for l:candidate in [a:mod . '.py', a:mod . '/__init__.py']
+            let l:found = findfile(l:candidate)  " search the `path`
+            if !empty(l:found)
+                return l:found
+            endif
+        endfor
+        return ''
+    endfunction
+
+    function! s:PyGoToFile()
+        let l:mod = s:PyModuleUnderCursor()
+        let l:file = empty(l:mod) ? '' : s:PyFindFile(l:mod)
+        if empty(l:file)
+            echohl ErrorMsg | echo 'No module file for: ' . l:mod | echohl NONE
+            return
+        endif
+        execute 'edit ' . fnameescape(l:file)
+    endfunction
+
+endif
+
+" <c-o> jumps back
+nnoremap <buffer><silent> gf  :call <SID>PyGoToFile()<cr>
+
+" Find `def`s and `class`es with [d and [D
+setlocal define=^\\s*\\<\\(def\\|class\\)\\>
+
+
+" Indentation settings come from ~/.config/vim/vimrc, and
+" `smartindent` is left off as it interferes with VIM's Python indent script
+
+
+" Auto-wrap lines after 88 characters, which is PEP8's limit plus 10%,
+" a more relaxed boundary which occasionally may be used
+setlocal textwidth=88
+
+
+" Make column 80 red to indicate PEP8's maximum allowed line length
+setlocal colorcolumn=80
+
+" Additionally, give every character beyond 80 columns a red background
+" (matches are window-local, so re-apply them per buffer)
+highlight ColorColumn ctermbg=DarkRed
+augroup python_overlength
+    autocmd! * <buffer>
+    autocmd BufEnter <buffer> call matchadd('ErrorMsg', '\%>80v.\+', 100)
+    autocmd BufLeave <buffer> call clearmatches()
+augroup END
+call matchadd('ErrorMsg', '\%>80v.\+', 100)
+
+
+" Show line numbers by default for .py files
+let g:show_numbers=1
+call ShowLineNumbers()

.config/vim/vimrc

@@ -0,0 +1,318 @@
+" Use VIM improved mode
+set nocompatible
+
+
+" Disable VIM's startup message
+set shortmess+=I
+
+" Number of remembered undo steps
+set undolevels=1000
+
+
+set runtimepath^=$XDG_CONFIG_HOME/vim
+set runtimepath+=$XDG_CONFIG_HOME/vim/after
+
+" Set environment variables for convenient usage
+let $RC = expand('$XDG_CONFIG_HOME/vim/vimrc')
+let $RTP=split(&runtimepath, ',')[0]
+
+
+" Detect the file's type and load the corresponding plugin and indent files
+filetype plugin indent on
+
+" Enable syntax highlighting
+syntax on
+
+
+" Configure tab behavior
+set expandtab      " Insert spaces instead of tab characters
+set tabstop=4      " Width of an existing tab character
+set shiftwidth=4   " Width of one >> or << indent step
+set softtabstop=4  " Width inserted/removed by <tab> and <bs>
+set shiftround     " Round indents to a multiple of shiftwidth
+set autoindent     " Keep the previous line's indent on a new line
+vnoremap <tab>    >gv
+vnoremap <s-tab>  <gv
+
+
+" Allow backspace to delete characters in insert mode
+" beyond the start of the insertion and end of lines
+set backspace=start,eol,indent
+
+
+" Hide buffers instead of closing them, which means we can have
+" unwritten changes to a file and open a new one with :e,
+" without having to write the changes first
+set hidden
+
+
+" Set to the folder of the current file and its sub-folders
+" (this may need to be adapted for large project folders)
+set path=.,**
+
+
+" Store all vim-related working files in the ~/.local/state/vim folder
+set viminfo+=n$XDG_STATE_HOME/vim/viminfo
+" Use dedicated folders to store temporary backup, swap, and undo files
+" (the // means that VIM adapts names automatically to avoid duplicates)
+set backupdir=$XDG_STATE_HOME/vim/backup//
+set directory=$XDG_STATE_HOME/vim/swap//
+set undodir=$XDG_STATE_HOME/vim/undo//
+set undofile
+
+" To disable any of the temporary files, uncomment one of the following
+" set nobackup
+" set nowritebackup
+" set noswapfile
+" set noundofile
+
+
+" Show the filename in the terminal window's title bar
+set title
+
+
+" Do not wrap lines when showing text
+set nowrap
+
+" This avoids a problem of losing data upon insertion in old VIMs
+set wrapmargin=0
+
+
+" Show spelling mistakes in italics
+
+augroup spelling
+    autocmd!
+    autocmd FileType markdown,text,gitcommit setlocal spell spelllang=en_us,de_de
+augroup END
+
+augroup spell_highlight
+    autocmd!
+    autocmd ColorScheme * hi clear SpellBad | hi clear SpellCap
+                      \ | hi clear SpellRare | hi clear SpellLocal
+                      \ | hi SpellBad cterm=italic
+augroup END
+silent! doautocmd ColorScheme
+
+
+" Show whitespace characters
+set listchars=tab:»»,extends:›,precedes:‹,nbsp:·,trail:·
+set list
+
+
+" Highlight matching brackets
+set showmatch
+set matchpairs+=<:>
+
+
+" Always show the status bar at the bottom
+set laststatus=2
+
+" Show current position in status bar
+set ruler
+set rulerformat=%=%l/%L\ %c\ (%P)
+
+" Show commands in status bar
+set showcmd
+
+" If in non-normal mode, show the mode in the status bar
+set showmode
+
+" Show a dialog to save changes instead of an error message
+set confirm
+
+" Auto-clear messages from the status bar
+augroup clear_messages
+    autocmd!
+    autocmd CursorHold * echo
+augroup END
+
+
+" Better copy and paste behavior (needs vim-gtk3 installed)
+if has('clipboard')
+    set clipboard=unnamed,unnamedplus
+endif
+
+
+" Make : and ; synonyms
+nnoremap ; :
+
+
+" Use \ and <space> as the <leader> keys and lower time to enter key sequences
+let mapleader='\'
+set timeoutlen=750
+" Make <space> the <leader> in visual mode as well
+nmap <space>  \
+vmap <space>  \
+
+
+" Q normally goes into Ex mode
+nmap Q  <Nop>
+
+
+" Get sudo rights when writing a buffer with w!!
+cnoremap w!!  w !sudo tee % >/dev/null
+
+
+" Fix mouse issues with Alacritty terminal
+" Source: https://wiki.archlinux.org/title/Alacritty#Mouse_not_working_properly_in_Vim
+set ttymouse=sgr
+
+
+" Enable the mouse for selections, including a toggle for this mode
+set mouse=a
+let g:mouse_enabled=1
+function! ToggleMouse()
+    if g:mouse_enabled == 1
+        echo "Mouse OFF"
+        set mouse=
+        let g:mouse_enabled=0
+    else
+        echo "Mouse ON"
+        set mouse=a
+        let g:mouse_enabled=1
+    endif
+endfunction
+noremap <silent><leader>m  :call ToggleMouse()<cr>
+
+
+" Enable toggling between
+"  - showing and hiding line numbers (<leader>l)
+"  - absolute and relative numbers (<leader>a) in normal mode
+"    (default: relative line numbering)
+let g:show_numbers=0
+let g:show_absolute_numbers=0
+function! ShowLineNumbers()
+    if g:show_numbers == 1
+        set number
+        if g:show_absolute_numbers
+            set norelativenumber
+        else
+            set relativenumber
+        endif
+    else
+        set nonumber
+        set norelativenumber
+    endif
+endfunction
+function! ToggleLineNumbers()
+    if g:show_numbers == 1
+        let g:show_numbers=0
+    else
+        let g:show_numbers=1
+    endif
+    call ShowLineNumbers()
+endfunction
+function! ToggleAbsoluteAndRelativeLineNumbers()
+    if g:show_absolute_numbers == 1
+        let g:show_absolute_numbers=0
+    else
+        let g:show_absolute_numbers=1
+    endif
+    call ShowLineNumbers()
+endfunction
+" Auto-switch between absolute and relative numbering when switching modes
+" (insert mode always shows absolute numbers when numbers are shown)
+augroup numbertoggle
+    autocmd!
+    autocmd BufEnter,FocusGained,InsertLeave * call ShowLineNumbers()
+    autocmd BufLeave,FocusLost,InsertEnter   * if g:show_numbers == 1 | set number | set norelativenumber | endif
+augroup END
+" Key bindings
+nnoremap <silent><leader>l  :call ToggleLineNumbers()<cr>
+nnoremap <silent><leader>a  :call ToggleAbsoluteAndRelativeLineNumbers()<cr>
+
+
+" Show all possible matches above command-line when tab completing
+set wildmenu
+set wildmode=longest:full,full
+
+
+" Highlight search results
+set hlsearch
+
+" Shortcut to remove current highlighting
+nnoremap <silent><leader>h  :nohlsearch<cr>
+
+" Move cursor to result while typing immediately
+set incsearch
+
+" Ignore case when searching
+set ignorecase
+
+" Upper case search term => case sensitive search
+set smartcase
+
+" Highlight the next match in red for 0.25 seconds
+function! HighlightNext()
+    let [bufnum, lnum, col, off] = getpos('.')
+    let matchlen = strlen(matchstr(strpart(getline('.'),col-1),@/))
+    let target_pat = '\c\%#\%('.@/.'\)'
+    let ring = matchadd('ErrorMsg', target_pat, 101)
+    redraw
+    exec 'sleep ' . float2nr(250) . 'm'
+    call matchdelete(ring)
+    redraw
+endfunction
+nnoremap <silent>n  n:call HighlightNext()<cr>
+nnoremap <silent>N  N:call HighlightNext()<cr>
+
+
+" Make <leader>w save the buffer in normal mode
+" and <c-z> save the buffer in all modes
+" (the latter disables making VIM a background job;
+"  <c-z> is useful to have as <leader>w does not work in INSERT mode)
+nnoremap <leader>w  :update<cr>
+nnoremap <c-z>      :update<cr>
+vnoremap <c-z>      <c-c>:update<cr>
+inoremap <c-z>      <c-o>:update<cr>
+
+" <leader>q quits VIM
+nnoremap <leader>q  :quit<cr>
+
+" Easier switching between tabs
+noremap <leader>,  <esc>:tabprevious<cr>
+noremap <leader>.  <esc>:tabnext<cr>
+
+" Arrow keys either (un)indent lines or move them up or down
+" (same for blocks of lines in visual mode)
+nnoremap <left>          <<
+nnoremap <right>         >>
+nnoremap <silent><up>    :m-2<cr>
+nnoremap <silent><down>  :m+<cr>
+vnoremap <left>          <gv
+vnoremap <right>         >gv
+vnoremap <up>            :m'<-2<cr>gv=gv
+vnoremap <down>          :m'>+1<cr>gv=gv
+
+" Make Y yank the rest of a line, just like C or D work
+nnoremap Y  y$
+
+" Alphabetically sort a selection of lines
+vnoremap <leader>s  :sort<cr>
+
+" Switch two words, just like xp switches two characters
+nnoremap <leader>xp  dwElp
+
+
+" Auto-reload a file that was changed by some other process
+" if the buffer has not yet been changed in the meantime
+set autoread
+set updatetime=1000
+augroup checktime
+    autocmd!
+    autocmd BufEnter     * silent! checktime
+    autocmd CursorHold   * silent! checktime
+    autocmd CursorHoldI  * silent! checktime
+augroup END
+
+
+" Auto-reload ~/.config/vim/vimrc on write for a fast edit loop
+" => NOTE: This adds to state rather than replacing it,
+"          so, for example, removed mappings and options persist
+"          until VIM is restarted
+augroup vimrc
+    autocmd!
+    autocmd BufWritePost $MYVIMRC source % | redraw
+augroup END
+" Key binding to reload ~/.config/vim/vimrc manually
+nnoremap <silent><leader>rc  :so $MYVIMRC<cr>

.inputrc

@@ -0,0 +1,14 @@
+# Enable vi-style line editing for all readline apps
+set editing-mode vi
+
+# Indicate the current mode via the cursor shape
+set show-mode-in-prompt on
+set vi-cmd-mode-string "\1\e[2 q\2"  # steady block
+set vi-ins-mode-string "\1\e[5 q\2"  # blinking beam
+
+# Ctrl-L clears the screen in command mode only
+# => Bind in insert mode as well
+set keymap vi-insert
+"\C-l": clear-screen
+
+set keymap vi