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Comment by clarry | Hacker News Reader

What would getopt look like in APL (also K, J, what have you)? I couldn't find any examples. Similarly, I'd like to see some examples of handling multiple I/O endpoints (sockets, stdio, files?) asynchronously (or should I say without blocking) using whatever mechanism works best in APL.

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It's literally 4 characters in Q.

.z.x

But in reality you'd probably use:

.Q.opt

(which is 6 characters!)

Update: reference to .Q.opt

See https://code.kx.com/q/ref/dotz/#zx-raw-command-line

Uhh.. no, that's just argv. Getopt is something you'd use to actually parse flags and arguments out of argv.

EDIT: Ok, .Q.opt looks a little better, although it's still not close to getopt (where -abc would be shorthand for three flags, -a -b -c; but other flags might be defined to take (possibly optional) arguments). Is it a built-in implemented in whatever K/Q is written in? How would you implement .Q.opt in K if it were not built in?

http://man.openbsd.org/getopt.3

http://cvsweb.openbsd.org/src/lib/libc/stdlib/getopt_long.c?...

Apologies - updated.

Yep you're right, it's definitely not doing as much as getopt, though it's the same general use case. It's output is a dictionary representing your command line arguments, which you'd then use in your program to act accordingly.

It's implemented in K and comes standard with the distrubution. If you've got a KDB+/Q distribution you can view the actual function definition by executing it without an argument:

  q).Q.opt
  k){[o]x::$[#i:&o like"-[^0-9]*";i[0]#o;o];((`$1_*:)'o)!1_'o:i_o}

Disclaimer: I cannot read K, and I'd consider myself a beginner in Q, so the above is completely alien to me. But what that does, in words: any "-single-dash-params" is treated as an option. It splits your 'argv' by those options. Everything between the options become the 'values' for the prior most recently preceding option. If you've got a no-arg option, it just becomes a member in the dictionary without a corresponding value:

  $ q -opt1 foo bar -opt2 baz -opt3
  q).Q.opt .z.x
  opt1| ("foo";"bar")
  opt2| ,"baz"
  opt3| ()

EDIT: formatting.

I would also like to know if there's examples of more real time applications in APL. Any GUI programming? Interactive simulations? etc.

Tangentstorm’s videos about J have some nice GUI examples. For example https://youtu.be/uL-70fMTVnw

Pretty cool thanks, this one covers interactivity https://invidio.us/watch?v=CzK2SazvCxM (it's a little sprite editor)

Do you know if GNU APL offers the facilities to do stuff like that?

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