Feature: shell-like combinators for conditional computation and sending several commands to server in a single batch

[nikitabobko]

Currently it's impossible to consume stdout and exit codes of commands in toml config. One has to use exec-and-forget

alt-w = 'exec-and-forget aerospace workspace W --fail-if-noop || aerospace workspace-back-and-forth'
atl-tab = 'exec-and-forget aerospace list-workspaces --all | aerospace workspace next'

It's slow. Communicating with the server back and forth from CLI client can take additional 100ms which becomes noticeable. Even if we fix the slowness somehow, annoying flickering will still remain an issue

It'd be cool if AeroSpace supported basic shell combinators (||, &&, ;, ( ))

alt-w = 'workspace W || workspace-back-and-forth'
atl-tab = 'list-workspaces --all | workspace next'

That's a big feature that lays the foundation for a lot of things (basically the combinators allow programming custom logic):

• It becomes possible to send a batch of commands from CLI to server at once, resulting in reduced flickering (because server already implements "double buffering" to reduce flickering)
  https://nikitabobko.github.io/AeroSpace/goodness#use-trackpad-gestures-to-switch-workspaces

  aerospace eval 'list-workspaces --monitor mouse --visible | xargs workspace; aerospace workspace next'

  Or alternatively without xargs:

  aerospace eval 'list-workspaces --monitor mouse --visible | workspace -; workspace next'
  

• It fixes the ugliness of on-window-detected TOML callback. The new syntax is much more compact and powerful. It remains readable for people familiar with shell:

  on-window-detected = '''
      test %{app-bundle-id} == com.jetbrains.intellij && move-workspace-to-monitor I
          || test %{app-bundle-id} == com.google.Chrome && move-node-to-workspace W
          || test %{app-bundle-id} == com.apple.dt.Xcode && (move-node-to-workspace X; exec-async 'echo hi!')
  '''

• It opens up a possibility for even more powerful conditional gaps [Feature Request] Large Monitor, Single App Window Size Concern #60:

  [gaps]
  outer.left = 'test %{workspace-tiling-windows-count} --lessThan 2 && echo 100'
  outer.right = 'test %{workspace-tiling-windows-count} --lessThan 2 && echo 100'

  UPD: this particular suggestion was discarded
• It makes everything more universal and reusable. E.g. there won't be need to fix Add command to programatically run all on-window-detected callbacks  #107 if config command allows to query on-window-detected command:

  aerospace eval 'config --get on-window-detected | eval -'

Other subcommands that AeroSpace has to implement to make the feature complete:

• test as in CLI but with possibility to interpolate AeroSpace special variables like %{window-title}, %{window-name}, %{app-bundle-id}, %{workspace-tiling-windows-count}, etc Implement test-regex command so users could more interactively test regexes the way they are implemented in AeroSpace #150
• xargs as in CLI UPD: stop turning it into a programming language. It's better to provide single dash - to a bunch of commands as in "consume stdin convention". xargs and interpolation (which is another idea, that I discard right now) have a downside that it becomes impossible to statically parse all commands in "AeroSpace script"
• echo as in CLI. (use case: Creating a new Workspace next to the current Workspace, send the current node / App to and focus it? #842)
• exec-async as a replacement for exec-and-forget. The problem with exec-and-forget that it's not parsed as real CLI command, making it impossible to use the command with combinators
• eval to evaluate "AeroSpace script" from argv[1]

Overall a lot issues can be fixed: #264 #60 #54 #174 (partially) #104 (partially) #107 (kinda) #150

Open question: doesn't it open a pandora box of own script programming language? It kinda does. I hope that people will never ask for loops.

[nikitabobko]

Draft:

on-window-detected = '''
    if test --app-bundle-id com.jetbrains.intellij.ce || test --app-bundle-id com.jetbrains.intellij do
        move-workspace-to-monitor I # [I]de
    elif test --app-bundle-id com.google.Chrome do
        move-node-to-workspace W # [W]eb browser
    elif test --app-bundle-id com.apple.dt.Xcode do
        move-node-to-workspace X; exec-async 'echo hi!' # [X]code
    end
'''

[nikitabobko]

Since it's a custom language (unfortunately), it'd be good to be able to print AST (Abstract Syntax Tree) for better discoverability and debugging

$ aerospace eval --print-ast-and-exit '
if test --app-bundle-id com.jetbrains.intellij.ce do
    move-workspace-to-monitor I
end

echo 'hi!'
'

IfBlock
    IfCondition
        Command
            ['test', '--app-bundle-id', 'com.jetbrains.intellij.ce']
    IfThenBlock
        Command
            ['move-workspace-to-monitor', 'I']
Command
    ['echo', 'hi!']

[jakenvac]

I think this sounds like it would be an incredible addition to the project.

Have you thought about using existing embeddable scripting languages such as lua? I think this would be great for several reasons: (I'll use lua as an example here, but there other options)

• Users can leverage existing tooling, such as:
  • text editor syntax highlighting
  • language server clients (With type def comments, in the case of lua lsp)
  • package managers for plugins/extensibility
• No need to maintain a custom language/interpreter/vm.
  • A good example of this is neovim with lua vs vim with vimscript. The vim project spends a significant amount of time implementing and maintaining vimscript, whereas neovim is able to iterate quickly and use a tried and tested scripting language with its own maintainers and development cycle.
• No need to embed scripts as strings in a toml file
• Things like callbacks can use an event handler pattern:

  aerospace.on('window-detected', function(window) print(window.app_bundle_id) end)

This of course would come with some cons, too:

• You miss out on the fun of building your own language 😄
• There doesn't seem to be any actively maintained swift bindings for lua specifically
• Overhead. Using a general scripting language vs something lean and bespoke could increase build sizes and potentially impact performance. (Although luajit is fast)
• It could be off putting to new users. Keeping a toml file that's easy to configure, with the option of extending by adding scripts as multiline strings is a good compromise to cater to newcomers and power users alike.

---

Edit: I've just found some incredibly well documented and up to date bindings for lua. Shocked it has so few stars. https://github.com/tomsci/LuaSwift

Edit 2: I don't know how I didn't think of this at first, but macos provides a great embeddable language in the form of JavaScriptCore. Part of apples webkit. It requires no third party dependencies and has a very easy to use swift/obj-c api.

Here's a very simple working code example, demonstrating just how easy it is to use.

import Foundation
import JavaScriptCore

let context = JSContext()

let addTwoNumbers: @convention(block) (Int, Int) -> Int = { num1, num2 in
    print("Adding two numbers: \(num1) + \(num2)")
    return num1 + num2
}

context?.setObject(addTwoNumbers, forKeyedSubscript: "addTwoNumbers" as NSString)

let jsScript = "addTwoNumbers(2, 3)"

if let result = context?.evaluateScript(jsScript) {
    print(result.toString() ?? "No result")
}

[tobiasgiese]

Have you thought about using existing embeddable scripting languages such as lua?

There is also a sketchybar lua plugin 🙂
https://github.com/FelixKratz/SbarLua

[osolmaz]

Just wanted up this

I currently use the following shortcuts, and the delay due to exec-and-forget feels significant

alt-p = 'exec-and-forget aerospace list-workspaces --monitor focused --empty no | aerospace workspace prev'
alt-n = 'exec-and-forget aerospace list-workspaces --monitor focused --empty no | aerospace workspace next'

As far as I've read here and in #264, this is supposed to help with that, no?

[bioe007]

+1 to the lua idea and just adding something (possibly obvious) but several very powerful tiling wms in the linux space (i3 and awesomewm) have

I was around in the pre-lua awesome wm days and the syntax included shelling things out as described here - it was hairy stuff.

Lua's syntax for a basic aerospace config would be arguably simple than the current toml.

[karadnik-flutterint]

Hi there, noob question: Why not give the user opportunity to write a swift function instead?
I guess, one obvious cons would be that not many people know swift, but still, if you want badly enough some feature, you will be able to stitch together a function.

[jakenvac]

@karadnik-flutterint you can already do this by creating a fork