Coqtail

Interactive Coq Proofs in Vim

Coqtail enables interactive Coq proof development in Vim similar to CoqIDE or ProofGeneral.

It supports:

• Coq 8.4 - 8.19
• Python >=3.6 (see here for older versions)
• Vim >=7.4 and Neovim >=0.3
• Simultaneous Coq sessions in different buffers
• Non-blocking communication between Vim and Coq (Vim >=8.0 and NeoVim only)

Installation

As a vim package:

mkdir -p ~/.vim/pack/coq/start
git clone https://github.com/whonore/Coqtail.git ~/.vim/pack/coq/start/Coqtail
vim +helptags\ ~/.vim/pack/coq/start/Coqtail/doc +q

Using pathogen:

git clone https://github.com/whonore/Coqtail.git ~/.vim/bundle/Coqtail
vim +Helptags +q

Using Vundle:

Plugin 'whonore/Coqtail' (add this line in .vimrc)
vim +PluginInstall +qa

Using VimPlug:

Plug 'whonore/Coqtail' (add this line in .vimrc)
vim +PlugInstall +qa

Requirements

• Vim compiled with +python3 (3.6 or later) or the pynvim Python package for Neovim
• Vim configuration options filetype plugin on, and optionally filetype indent on and syntax on (e.g. in .vimrc)
• Coq 8.4 - 8.19

Newer versions of Coq have not yet been tested, but should still work as long as there are no major changes made to the XML protocol. Note that for Coq >=8.9, the coqidetop executable must be available, which may require additionally installing CoqIDE depending on the installation method. See here for help with pointing Coqtail to the appropriate location.

Usage

Coqtail provides the following commands (see :help coqtail for more details):

Command	Mapping	Description
Starting and Stopping
CoqStart	<leader>cc	Launch Coqtail in the current buffer.
CoqStop	<leader>cq	Quit Coqtail in the current buffer.
CoqInterrupt	CTRL-C	Send SIGINT to Coq.
Movement
{n}CoqNext	<leader>cj	Send the next n (1 by default) sentences to Coq.
{n}CoqUndo	<leader>ck	Step back n (1 by default) sentences.
{n}CoqToLine	<leader>cl	Send/rewind all sentences up to line n (cursor position by default). n can also be $ to check the entire buffer.
{n}CoqOmitToLine	No default (see Mappings)	Same as CoqToLine, but skip processing of and admit all opaque proofs. Similar to Proof General's proof-omit-proofs-option. See :help CoqOmitToLine for more information.
CoqToTop	<leader>cT	Rewind to the beginning of the file.
CoqJumpToEnd	<leader>cG	Move the cursor to the end of the checked region.
CoqJumpToError	<leader>cE	Move the cursor to the start of the error region.
CoqGotoDef[!] <arg>	<leader>cgd	Populate the quickfix list with possible locations of the definition of <arg> and try to jump to the first one. If your Vim supports 'tagfunc' you can also use CTRL-], :tag, and friends.
Queries
Coq <args>		Send arbitrary queries to Coq (e.g. Check, About, Print, etc.).
Coq Check <arg>	<leader>ch	Show the type of <arg> (the mapping will use the term under the cursor or the highlighted range in visual mode).
Coq About <arg>	<leader>ca	Show information about <arg>.
Coq Print <arg>	<leader>cp	Show the definition of <arg>.
Coq Locate <arg>	<leader>cf	Show where <arg> is defined.
Coq Search <args>	<leader>cs	Show theorems about <args>.
Panel Management
CoqRestorePanels	<leader>cr	Re-open the Goal and Info panels.
{n}CoqGotoGoal	<leader>cgg	Scroll the Goal panel to the start of the nth goal (defaults to 1). Number of lines shown is controlled by g:coqtail_goal_lines.
{n}CoqGotoGoal!	<leader>cgG	Scroll the Goal panel to the end of the nth goal.
CoqGotoGoalNext	]g	Scroll the Goal panel to the start of the next goal.
CoqGotoGoalNext!	]G	Scroll the Goal panel to the end of the next goal.
CoqGotoGoalPrev	[g	Scroll the Goal panel to the start of the previous goal.
CoqGotoGoalPrev!	[G	Scroll the Goal panel to the end of the previous goal.

Configuration

Mappings

The mappings above are set by default, but you can disable them all and define your own by setting g:coqtail_nomap = 1 in your .vimrc. Some of the commands, such as CoqNext, also have insert-mode mappings by default, which can be disabled with g:coqtail_noimap.

Alternatively, you can keep the defaults but remap specific commands. For example, use map <leader>ci <Plug>CoqInterrupt to avoid hijacking CTRL-C. If a mapping for a command already exists when Coqtail is loaded, the default mapping for that command won't be defined.

The <leader>c prefix may be inconvenient depending on your mapleader setting. In that case you can set a custom prefix with g:coqtail_map_prefix (or g:coqtail_imap_prefix for just insert-mode mappings).

Finally, after defining the standard keybindings, Coqtail will call a vim function named CoqtailHookDefineMappings (if one is defined). This makes it easy to add additional mappings without removing the standard mappings, and to add mappings which are only active in Coqtail-managed buffers. One way to use this hook is to make bindings for commands which augment the standard Coqtail bindings instead of replacing them. One concrete example is:

function CoqtailHookDefineMappings()
  imap <buffer> <S-Down> <Plug>CoqNext
  imap <buffer> <S-Left> <Plug>CoqToLine
  imap <buffer> <S-Up> <Plug>CoqUndo
  nmap <buffer> <S-Down> <Plug>CoqNext
  nmap <buffer> <S-Left> <Plug>CoqToLine
  nmap <buffer> <S-Up> <Plug>CoqUndo
endfunction

Adding that snippet to your .vimrc would create new bindings for CoqNext, CoqToLine, and CoqUndo. Those bindings would be active in all Coq buffers, including Coqtail panels, but inactive in other buffers. The standard Coqtail bindings (<leader>cj, etc) would remain active.

Coq Executable

By default Coqtail uses the first coq(ide)top(.opt) found in your PATH. Use b:coqtail_coq_path (or g:coqtail_coq_path) to specify a different directory to search in (these are automatically set if the $COQBIN environment variable is set). You can also override the name of the Coq executable to use with b:coqtail_coq_prog (or g:coqtail_coq_prog). For example, to use the HoTT library:

let b:coqtail_coq_path = '/path/to/HoTT'
let b:coqtail_coq_prog = 'hoqidetop'

Project Files

There are two standard methods for configuring Coq project settings: _CoqProject files, and dune projects. Coqtail supports both, and while it should usually do the right thing by default, its behavior can be controlled by setting the g:coqtail_build_system option to one of 'prefer-dune' (default), 'prefer-coqproject', 'dune', or 'coqproject'. Additional arguments can also be passed to the Coq executable through :CoqStart (e.g., :CoqStart -w all).

Dune Settings

Dune projects can be configured to automatically compile the dependencies for the current file on :CoqStart by setting g:coqtail_dune_compile_deps = 1.

_CoqProject Settings

By default, Coqtail searches the current and parent directories for a _CoqProject file, but additional or different project files can be specified with g:coqtail_project_files. If multiple files are found, their argument lists will be concatenated. For example, to include arguments from both _CoqProject and _CoqProject.local:

let g:coqtail_project_files = ['_CoqProject', '_CoqProject.local']

Syntax Highlighting and Indentation

Coqtail also comes with an ftdetect script for Coq, as well as modified versions of Vincent Aravantinos' syntax and indent scripts for Coq. These scripts are used by default but can be disabled by setting g:coqtail_nosyntax = 1 and g:coqtail_noindent = 1 respectively. Formatting of comments can be disabled with g:coqtail_noindent_comment.

In addition to the Coq syntax, Coqtail defines highlighting groups for the sentences that are currently or have already been checked by Coq (CoqtailSent and CoqtailChecked), any lines that raised an error (CoqtailError), and the beginnings and ends of omitted proofs (CoqtailOmitted). By default these are defined as:

if &t_Co > 16
  if &background ==# 'dark'
    hi def CoqtailChecked ctermbg=17 guibg=#113311
    hi def CoqtailSent    ctermbg=60 guibg=#007630
  else
    hi def CoqtailChecked ctermbg=17 guibg=LightGreen
    hi def CoqtailSent    ctermbg=60 guibg=LimeGreen
  endif
else
  hi def CoqtailChecked ctermbg=4 guibg=LightGreen
  hi def CoqtailSent    ctermbg=7 guibg=LimeGreen
endif
hi def link CoqtailError Error
hi def link CoqtailOmitted coqProofAdmit

To override these defaults simply set your own highlighting (:help :hi) before syntax/coq.vim is sourced (e.g., in your .vimrc). Note, however, that many colorschemes call syntax clear, which clears user-defined highlighting, so it is recommended to place your settings in a ColorScheme autocommand. For example:

augroup CoqtailHighlight
  autocmd!
  autocmd ColorScheme *
    \  hi def CoqtailChecked ctermbg=236
    \| hi def CoqtailSent    ctermbg=237
augroup END

If you feel distracted by the error highlighting while editing a failed sentence, you can use the sequence <leader>cl (:CoqToLine) while the cursor is inside that sentence. If it isn't, you can use <leader>cE (:CoqJumpToError) to move it to an appropriate position.

Proof Diffs

Since 8.9, Coq can generate proof diffs to highlight the differences in the proof context between successive steps. To enable proof diffs manually, use :Coq Set Diffs "on" or :Coq Set Diffs "removed". To automatically enable proof diffs on every :CoqStart, set g:coqtail_auto_set_proof_diffs = 'on' (or = 'removed'). By default, Coqtail highlights these diffs as follows:

hi def link CoqtailDiffAdded DiffText
hi def link CoqtailDiffAddedBg DiffChange
hi def link CoqtailDiffRemoved DiffDelete
hi def link CoqtailDiffRemovedBg DiffDelete

See the above instructions on how to override these defaults.

More Options

See :help coqtail-configuration for a description of all the configuration options.

Vim Plugin Interoperability

Jumping between matches

Coqtail defines b:match_words patterns to support jumping between matched text with % using the matchup or matchit plugins.

Automatically closing blocks

Coqtail defines patterns to enable automatic insertion of the appropriate End command for code blocks such as Sections, Modules, and match expressions with endwise.

Tags

Coqtail supports the :tag family of commands by locating a term on the fly with tagfunc. However, as this relies on Coq's Locate command, it only works if the point where the term is defined has already been evaluated by Coq. An alternative is to disable Coqtail's default tagfunc (let g:coqtail_tagfunc = 0) and instead use universal-ctags in conjunction with coq.ctags, to statically generate a tags file. This works especially well with something like the gutentags plugin to automatically keep the tags file in sync with the Coq source.

Latex/Unicode input

Coqtail and Coq can handle non-ASCII characters in identifiers, notations, etc., but Coqtail does not provide a method for inputting these characters itself. Instead one can use one of the native Vim options (e.g., i_CTRL-K or i_CTRL-V_digit) or a plugin like latex-unicoder or unicode.vim.

Thanks

Parts of Coqtail were originally inspired by/adapted from Coquille (MIT License, Copyright (c) 2013, Thomas Refis).

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Python 2 Support

Python 2 and 3.5 have reached their end-of-life so Coqtail no longer supports them in order to simplify the code and take advantage of newer features. See YouCompleteMe for help building Vim with Python 3 support. If you cannot upgrade Vim, the python2 branch still supports older Pythons.