Show HN: val – An arbitrary precision calculator language | Hacker News Reader

Show HN: val – An arbitrary precision calculator language

github.com

34 pointscrap19 comments

Wrote this to learn more about the `chumsky` parser combinator library, rustyline, and the `ariadne` error reporting crate.

Such a nice DX combo for writing new languages.

Still a work in progress, but I thought I'd share :)

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The UI is awesome, amazing work! However, arbitrary precision implies that there is no fixed upper limit to the number of digits - simple tests like `0.1 + 0.2 == 0.3` and `2^53 == 2^53 + 1` (both produce "false") indicates you're still using IEEE 754 double precision floats.

If "arbitrary precision" is not as important to you as "high precision", a 128 bit decimal has enough precision for 99% of real-world applications.

Thanks for checking it out! Should have been more clear that this is actively being worked on. This is ultimately the goal, and I'm currently working on integrating `astro_float` as the base for numbers.

That is awesome, I look forward to following the project and hopefully contributing! I became a better Rust programmer from reading your code :)

Do you mean, the first returns false and the second returns true?

Ah you're right, thank you for pointing it out!

In the previous version of this comment (where I was still reading it incorrectly) I added a fun fact, that the significand of an IEEE 754 double-precision float is only allocated 52 bits, but the "hidden bit trick" provides an extra bit of precision when the normalized form starts with 1.

Rewrite it like so

> 1/10 + 2/10 == 3/10 true >

Thanks to everyone who gave feedback!

Arbitrary precision is now supported in 0.3.0 after integrating the `astro_float` (https://docs.rs/astro-float/latest/astro_float/index.html) `BigFloat` type as the base for numbers in the language.

Still working out the kinks, but its live so give it a try!

> sqrt(10^100)-1 -> 100000000000000000000000000000000000000000000000000

Not what I expected.

In the readme it says it uses double precision for numbers. Also not quite whet I expected from 'arbitrary precision'.

Hmm, yeah. It cites `bc` as prior art, which is quite widely used; but another interesting arbitrary-precision calculator is spigot https://www.chiark.greenend.org.uk/~sgtatham/spigot/spigot.h...

Also the AOSP calculator, of course[1,2,3].

[1] https://chadnauseam.com/coding/random/calculator-app

[2] https://dl.acm.org/doi/10.1145/2911981

[3] https://dl.acm.org/doi/10.1145/3385412.3386037

Ivy does big numbers (not arbitrary) but does rationals too. It's an APL subset.

    0.1 + 0.2
    3/10

https://github.com/robpike/ivy

the addition of astro_float fixed this.

Hey nice! We have similar interests. I built something similar, but with way less calculator functionality than you did :D

But the main idea I was going for was real-time JIT evaluation with rendered errors (specifically learning / using cranelift JIT) - less to do with the calculator aspect.

I ended up choosing miette for errors.

https://github.com/jasonjmcghee/basic-treesitter-cranelift-j...

This is cool.

It love to have to base conversion functions, even if it's print only. Does that fit at all?

This definitely fits, base conversion is on the roadmap!

and different input base notations, 0x, o, 0b etc

I wish you well. And I clicked you a star on github. Keep up the good work.

very cool, welcome to the small club of CLI calculator authors! before I read this I knew of frink and crag (https://raku.land/zef:librasteve/App::Crag since you ask)

Crag is built on raku so has some neat tricks up its sleeve - you can see Crag of the Day to see some in action...

  crag '0.1+0.2=0.2'   #True (arbitrary precision)
  crag '₃₆123.45'      #3F.G77777  (base 36)
  crag 'e ** (i * π) =~= -1'   #True  (math symbols, complex numbers)
  crag '0rMCMXLIV'     #1944 (Roman numerals)
  crag '^<௪௨ mph>'     #42mph  (Unicode and units)

hee hee

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