Last Action Hero

This sort of thing happens to me all the time:

$ emacs readme.md
The file readme.md does not exist.
$ touch readme.md
$ emacs readme.md

Or maybe I'm just lsing a bunch of directories and find one I need to get into:

$ ls /long/path/to/where/ever
$ cd /long/path/to/where/ever

Or I want to remind myself of what a shell function does before running it, so I run cat. But I see something's off, so I need to make a quick update:

$ cat ~/.config/fish/functions/today.fish
$ emacs ~/.config/fish/functions/today.fish

There are three ways to create that second command:

1. Type the whole thing out.
2. Hit the up arrow, alt-arrow back through the path, delete the cat, type in emacs.
3. The same as #2 but you hit ctrl-a instead of alt-arrowing.

And here's a fourth method:

$ lah emacs

lah stands for Last Action Hero. It finds the last non-lah command in your history, replaces the executable's name with the new name you provide, and executes that new command.

So

$ emacs readme.md
The file readme.md does not exist.
$ lah touch

will run touch readme.md, and then

$ lah emacs

will run emacs readme.md.

If you enter more than one parameter, it will append the rest to the end of the new command. So, following the above,

$ lah emacs notes todo.org

will run emacs readme.md notes todo.org.

Notes

This is an alpha. It's my first work with Racket.

It currently only works with the fish shell.

It will spit a #t after the new command runs. This is Racket's true value and its appearance in your terminal means that lah ran fine. I just don't yet know how to prevent that from appearing.

Installation

1. Clone the repository.
2. Symlink dist/bin/lah somewhere in your $PATH.

FAQ

This isn't really the best way to do this, is it?

No, not at all.

So why write it?

Because Lisp is a wonderful language and I'm not nearly as familiar with it as I'd like to be. I caught the bug and had to write it out.

Here's a fish function to accomplish basically the same thing:

function lah
  set old_cmd $history[1]
  set old_exec (echo $old_cmd | cut -f 1 -d ' ')
  set new_exec $argv[1]
  set new_cmd (echo $old_cmd | sed "s/$old_exec/$new_exec/")
  eval $new_cmd
end

You'd make a terrible CTO, wouldn't you?

Yes, probably.