Show HN: val – An arbitrary precision calculator language
18 comments
·April 17, 2025primitivesuave
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.
johannesrexx
Rewrite it like so
> 1/10 + 2/10 == 3/10 true >
crap
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.
primitivesuave
That is awesome, I look forward to following the project and hopefully contributing! I became a better Rust programmer from reading your code :)
jdhwosnhw
Do you mean, the first returns false and the second returns true?
primitivesuave
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.
crap
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!
occamatl
> sqrt(10^100)-1 -> 100000000000000000000000000000000000000000000000000
Not what I expected.
emaro
In the readme it says it uses double precision for numbers. Also not quite whet I expected from 'arbitrary precision'.
chriswarbo
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...
mananaysiempre
Also the AOSP calculator, of course[1,2,3].
[1] https://chadnauseam.com/coding/random/calculator-app
lttlrck
the addition of astro_float fixed this.
jasonjmcghee
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...
lttlrck
This is cool.
It love to have to base conversion functions, even if it's print only. Does that fit at all?
crap
This definitely fits, base conversion is on the roadmap!
lttlrck
and different input base notations, 0x, o, 0b etc
I_complete_me
I wish you well. And I clicked you a star on github. Keep up the good work.
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 :)