ABS 1.2: background commands & the ability to import files

A few weeks ago the ABS team managed to pull together a new minor release of the language, 1.2.0, which includes loads of interesting features — let’s get to them!

~/.absrc

ABS will now look for a default ~/.absrc file to preload everytime you run a script: this is especially useful if you’d like to dump “base” functions you’re likely to re-use across scripts in a common place. Your .absrc could look like:

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tenth = f(x) {
    return x / 10
}

so that in any other abs script you can tenth(x).

~/.abs_history

We also introduced an history file in order to be able to repeat commands easily when using the ABS repl: this is, by default, located at ~/.abs_history and gets synced every time you close a repl session:

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$ abs
Hello alex, welcome to the ABS (1.2.0) programming language!
Type 'quit' when you're done, 'help' if you get lost!
⧐  `sleep 1`

⧐  quit
Adios!
$ tail ~/.abs_history
`sleep 1`

require(file)

A big one here: you can now require external files through require(path/to/file.abs ). This is a stepping stone in order to allow creating base libraries that can be re-used across ABS scripts, and organize ABS code a tad better.

Background commands

Another big feature here: you can now issue “background” commands that won’t block your ABS script (these commands are executed within a Goroutine).

A background command differs from a regular one simply because it employs an & at the end of the command itself — let’s see them in action:

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`sleep 10`
echo("Hello world!") # This will be printed after 10s

`sleep 10 &`
echo("Hello world!") # This will be printed immediately

You can check whether a background command is done with the .done property:

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cmd = `sleep 10 &`
cmd.done # false
wait(10000)
cmd.done # true

and we’ve added the wait() function if you need to block until the command is done:

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cmd = `sleep 10 &`
cmd.wait() # The script will be blocked for 10s
echo("Hello world!")

Misc

A few more features that made it into this release:

• number functions such as floor, round and ceil
• cd(), which switches the cwd of a script
• you can play around with your prompt by setting the environment variables ABS_PROMPT_LIVE_PREFIX=true and ABS_PROMPT_PREFIX=templated_string. The templated string can use {dir}, {user}, {host} that will be replaced on-the-fly. For further info, have a look at the sample .absrc file

Bugfixes

As usual, we managed to fix some minor bugs along the way:

• fixed a few random panics when calling built-in functions without enough arguments (#193)
• windows commands are now using cmd.exe rather than bash, as bash might not be available on the system (#180)
• better error messages when parsing “invalid” numbers (#182)
• the ABS installer was not working with wget 1.20.1 (#178)
• the ABS parser now supports numbers in scientific notation (eg. 8.366100560806463e-7, #174)
• errors on built-in functions would not report the correct error line / column numbers (#168)

Now what?

Install ABS with a simple one-liner:

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bash <(curl https://www.abs-lang.org/installer.sh)

…and start scripting like it’s 2019!

PS: Again, many thanks to Erich, who’s been taking a larger role as the weeks went by. Without him, many of the stuff included in 1.2 wouldn’t be possible!

PPS: 1.3.0 is already well underway — expect it at some point in April. We’ll be introducing extremely interesting features such as the ability to kill background commands, so it’s going to be an exciting release!