facsimile

(noun) : something clever, trevor

A terminal text editor written in modern Fortran. It keeps VSCode's keys where a terminal can express them, and says so plainly where it can't.

fac                 # welcome menu: recent workspaces and files
fac notes.md        # open a file
fac src/parser      # open a directory as a workspace

Why

Fortran is a language people assume you write numerical kernels in and nothing else. fac is the argument that the assumption is about the ecosystem rather than the language. Everything above the system call is Fortran: the gap buffer, the ANSI renderer, the JSON parser that talks to language servers, the syntax highlighter. C appears only where an iso_c_binding shim is the only way through — termios, forkpty, POSIX regex, the pipes to an LSP process.

The practical goal is narrower: an editor that starts instantly, holds a whole project without a config file, and doesn't need a plugin to open a second file.

Install

# Homebrew
brew install FortranGoingOnForty/tap/facsimile

# Arch (AUR)
yay -S facsimile

Or take a tarball for Linux, macOS or Windows from Releases.

From source

Needs gfortran and a C compiler. The Makefile picks the toolchain per platform — Homebrew gfortran on Apple silicon, plain gfortran elsewhere.

make            # -> ./fac
make dev        # warnings and runtime checks
make debug      # -O0 with backtraces
make info       # what it detected

There is also an fpm build (fpm run -- file.txt), used by the test suite. make is the release path.

What you get

Workspaces. Open a directory and fac remembers it: which files were open, where each caret was, how the panes were split, whether the tree was showing. It comes back that way. State lives in .fac/workspace.json at the workspace root — not in a dotfile in your home directory deciding things for every project at once.

Tab groups. A sub-workspace inside a workspace. Press enter on a directory in the file tree, tick the files you want, and they collapse into one tab-bar entry — src/ (4) — with their own row while you are inside it. Members are read from disk the first time you look at them, so a forty-file group costs one file read rather than forty.

Panes. alt-v and alt-s split the view; each pane keeps its own viewport and caret over the same buffer. Drag a tab off the bar into a pane's left, right or bottom quarter to split the file into place — a band shows the shape before you let go.

An integrated terminal (f5) that knows it is inside an editor. Typing fac notes.md at its prompt opens a tab in the session you are already in, rather than starting a second editor inside the first.

Language servers, detected and installed per language, with go-to- definition, references, project-wide rename, diagnostics, code actions and document formatting. See docs/LSP_GUIDE.md.

A git-aware file tree (ctrl-b) showing staged, modified and untracked status inline, with stage, unstage, commit, push and pull behind a ctrl-g prefix — single letters stay free for fuzzy search.

Inline AI completion from a local model, off until you turn it on with alt-i. Nothing runs, connects or leaves your machine before that. See docs/AI_COMPLETION.md.

Keys

The full list is F1 inside the editor, or docs/KEYBINDINGS.md. Enough to get moving:

Find

ctrl-f on a word searches for that word without your typing it, lights every occurrence, and draws the one you are on differently from the rest. The bar stays up while you walk them: arrows, page keys, enter, tab and space step forward, add shift to step back, home and end are the first and last. Typing replaces the seeded word and re-searches as you go. A second ctrl-f puts the bar away and leaves the matches lit for n/N; esc ends the search.

Multiple cursors

ctrl-d takes the next match, alt-click adds one anywhere, and ctrl-alt-up/down adds one on the line above or below. That last one has two aliases — super-up/down and ctrl-shift-alt-up/down — because GNOME and KDE take ctrl+alt+arrows for workspace switching and super+arrows for window tiling, and never pass them on. The three-modifier chord is the one neither desktop wants.

Mouse

Click to place the caret, drag to select, alt-click for another cursor, right-click for a context menu at the pointer. The wheel scrolls whatever is under it — the active pane, an inactive one, the terminal's scrollback — and does nothing over the tab bar, rather than moving a document you are not pointing at.

Tabs drag along the bar to reorder, into a pane to split, or onto a group to join it. Right-clicking inside a selection keeps the selection, so Cut and Copy act on it rather than on the line.

Full detail in docs/KEYBINDINGS.md.

Terminals

Some chords never reach a terminal program at all, and it is the terminal or the desktop eating them, not fac:

python3 tools/keycap.py shows what your terminal actually delivers for a given key, which settles the question faster than guessing does.

ctrl-/ and ctrl-? are the same byte (0x1F) under the legacy encoding, so fac asks for the kitty keyboard protocol at startup to tell them apart. Where that is declined — including inside tmux without set -g extended-keys on — ctrl-/ toggles a comment and F1 opens help.

To get ctrl-shift-z back in WezTerm:

config.keys = {
  { key = 'Z', mods = 'CTRL|SHIFT', action = wezterm.action.DisableDefaultAssignment },
}

Under it

A gap buffer for the text, ANSI escape sequences for the screen, and small C wrappers where POSIX has no Fortran interface: raw mode, the pseudoterminal behind the integrated terminal, POSIX regex, and the pipes to language server subprocesses. Cursor positions are UTF-8 character indices throughout, converted to bytes only where a C interface demands it.

Docs

• KEYBINDINGS.md — every key, and why some are odd
• LSP_GUIDE.md — language servers
• AI_COMPLETION.md — inline completion setup
• THEMES.md — built-in themes, terminal capabilities, and custom theme schema
• WORKSPACE_QUICKSTART.md — workspaces and the fortress
• config_spec.md — settings reference

License

MIT