dt
It's duct tape for your unix pipes. A programming language for doing small stuff fast, easy, and readable.
In the words of Red Green:
Remember, it's only temporary... unless it works!
Note: The dt User Guide exists but is still in progress. Basic usage is shown in the instructions below.
Use in pipes
When piping in/out, the REPL is skipped. If something is piping into dt then
standard input is fed into dt as a list of lines.
$ seq 3 | dt rev pls
3
2
1
Great for aliases:
$ alias scream-lines="dt [upcase words unlines] map pls"
$ echo "hey you pikachu" | scream-lines
HEY
YOU
PIKACHU
If you want to read lines manually, use stream as the first command:
$ alias head.dt="dt stream [rl pl] args last to-int times"
$ seq 100 | head.dt 3
1
2
3
Use as a shebang
When the first argument to dt is a file starting with #! it will interpret
the file. In short: dt supports shebang scripting.
A naive tee implementation:
tee.dt
#!/usr/bin/env dt
readln unlines \stdin :
args pop \file :
stdin pl
stdin file writef
Then use like:
cat wish-list | sed 's/red/green/g' | tee.dt new-wish-list
Interactive mode
Running dt by itself with no pipes in or out starts a read-eval-print loop
(REPL).
$ dt
dt 1.x.x
Now, this is only temporary... unless it works.
» # Comments start with #
»
» 1 1 + println
2
»
» # Printing is common, so there are a bunch of printing shorthands.
» # "p" is print, "pl" is print line, "pls" is print lines (i.e. of a list of values)
» # Let's define a command that consumes a value, prints it, then returns its double.
»
» [ \n : n p " " p n 2 *] \print-and-double def
»
»
» # And let's do it... 7 times!
»
» 1 \print-and-double 7 times drop
1 2 4 8 16 32 64
»
»
» # You can conditionally execute code
»
» ["hi" pl] false do?
» ["bye" pl] true do?
bye
»
» quit
For a best experience, also install
rlwrap and set a shell alias like so:
$ alias dtsh='rlwrap dt'
$ dtsh
dt 1.x.x
Now, this is only temporary... unless it works.
»
The above example assumes a bash-like shell. Details on the syntax and configuration files to set an alias that persists will vary by your shell.
Installing
The nerdy stuff
The dt language is a functional programming language, and a concatenative language, with a very imperative feel. For those interested, the user guide has a more in-depth discussion of the language classification.
dt is implemented in Zig with no plans to self-host or rewrite in Rust or Go.
Please do suggest better strategies for memory management and optimizations! I
have some experience working at this level, but still much to learn. The
current implementation is still fairly naive.
Credits
Shared as open source software, distributed under the terms of the 3-Clause BSD License.
By J.R. Hill | https://so.dang.cool | https://github.com/booniepepper