privy is a preprocessor/postprocessor for the array language ivy.

Given a source file, privy will produce a modified source file containing inline output from the expressions. For example, this input:

input = 199 200 208 210 200 207 240 269 260 263

butlast = -1 drop input
#=

butfirst = 1 drop input
#=

+/ 1 == sgn butfirst - butlast

Becomes:

input = 199 200 208 210 200 207 240 269 260 263

butfirst = 1 drop input
#= 200 208 210 200 207 240 269 260 263

butlast = -1 drop input
#= 199 200 208 210 200 207 240 269 260

+/ 1 == sgn butfirst - butlast
#= 7

Output lines start with #=. Error lines start with #!, and are reported inline with the errors:

input = 199 200 208 210 200 207 240 269 260 263

butfirst = 1 drop input
#= 200 208 210 200 207 240 269 260 263

butlast = -1 drop input
#= 199 200 208 210 200 207 240 269 260

#! undefined variable "buttfirst"
+/ 1 == sgn buttfirst - butlast
#! unreachable
#= 7

privy currently searches for ivy on your PATH, with no way to customize that.

At the moment all ivy programs are valid privy programs, and vice-versa. This may change in the future as I add the ability to easily import values and function definitions from other files.

With no arguments, privy will read from stdin and print to stdout. With a positional argument, privy will read that file and print to a file suffixed with .out. In other words, these are equivalent:

$ privy file.ivy

$ privy <file.ivy >file.ivy.out

privy "compiles" its input:

input = 199 200 208 210 200 207 240 269 260 263

butlast = -1 drop input
#=

butfirst = 1 drop input
#=

+/ 1 == sgn butfirst - butlast

Into a corresponding ivy program:

input = 199 200 208 210 200 207 240 269 260 263

butlast = -1 drop input
butlast
"\x00"

butfirst = 1 drop input
butfirst
"\x00"

+/ 1 == sgn butfirst - butlast
"\x00"

Then it executes that program, splits the output on null bytes, and interleaves it with the original input.

You will notice the fragility: privy will fail to associate output to the correct input lines if your program outputs single null bytes like this. There is currently no way to choose a different output terminator.

Also, I lied to you. It produces something more complicated than this, in order to preserve the behavior of the _ automatic variable. The actual output from the above program is:

_ = 0 rho 0
input = 199 200 208 210 200 207 240 269 260 263

_privy = _
butlast = -1 drop input
butlast
"\x00"
_ = _privy

_privy = _
butfirst = 1 drop input
butfirst
"\x00"
_ = _privy

+/ 1 == sgn butfirst - butlast
_privy = _
"\x00"
_ = _privy

Note that _ will always begin initialized to something. This means certain invalid ivy programs are valid privy programs, but like that's just an implementation detail leaking out. Don't rely on that.

If you pass the flag --dump-intermediate, privy will print this intermediate result to stderr before passing it to ivy.

There are cram tests that you can run or peruse:

$ cram test.t

Unfortunately trailing spaces are significant to cram, so be careful your editor doesn't trim them.

privy requires Janet 1.16.1, because this is the latest version of Janet packaged for Nix with a working jpm. You can enter a nix-shell with all of the correct dependencies by running:

nix-shell -I "nixpkgs=https://api.github.com/repos/NixOS/nixpkgs/tarball/$(cat shell.nix.lock)"