Implementing a bignum calculator – Rob Pike [video]

https://www.youtube.com/watch?v=PXoG0WX0r_E

by mseepgood • 12 years ago

76 25 12 years ago

Rob mentions a video demonstrating the development of an APL version of Conway's Game Of Life. Pretty sure it's this one if anyone is interested: http://youtu.be/a9xAKttWgP4

xkarga00• 12 years ago

Github repo:

https://github.com/robpike/ivy

willvarfar2• 12 years ago

He wants to compute some bignums, so he writes an APL interpreter in Go...

Now he is scratching his itch and making nice slides to boot.

However, it would have been simpler for him to have typed "python" at the commandline... Python ints are arb precision :)

raverbashing• 12 years ago

Python ints are arb precision

Python 2 longs or Python 3 ints ;)

willvarfar2• 12 years ago

Automatic promotion from a 32-bit or 64-bit storage to arbitrary precision.

pjmlp• 12 years ago

Lisp would be even better, as he would get the speed of compiled language.

mseepgood• 12 years ago

In the video he says that he already implemented an APL interpreter in Lisp.

arthurbrown• 12 years ago

Arbitrary precision is handled by https://golang.org/pkg/math/big/

He isn't implementing a bignum package, this is all about the APL interpreter.

dsymonds• 12 years ago

Yes, but he wasn't trying to compute numbers. He was trying to build a calculator. There's a difference.

lispm2• 12 years ago

or GNU CLISP which not only has big ints, big ratios, big complex (like all Common Lisp implementations), but also big floats.

Big ratios:

    [2]> (/ 5723475972349572938475982734985723984759823749587 7239457928374598723984759237459723497598234)
    5723475972349572938475982734985723984759823749587/7239457928374598723984759237459723497598234

Big complex numbers:

    [4]> (* 572934759237495723482374957239475982374957239847523485 (sqrt -1))
    #C(0 572934759237495723482374957239475982374957239847523485)

Big float numbers:

    [8]> (SETF (EXT:LONG-FLOAT-DIGITS) 1000)
    1000
    [9]> (sqrt 2.0l0)
    1.4142135623730950488016887242096980785696718753769480731766797379907324784621070388503875343276415727350138462309122970249248360558507372126441214970999358314132226659275055927557999505011527820605714701095599716059702745345968620147285174186408891986095523292304843087143214508397626036279952514079896872534L0

angersock2• 12 years ago

Ah yes, but a small userbase!

tptacek• 12 years ago

The premise of this comment being that it hadn't occurred to Rob Pike that there were already arbitrary-precision calculators.

zaphar• 12 years ago

You misattribute the motivation. He wants to play.

Implementing a BigNum calculator using APL concepts is one way to play. I do this all the time. I'll implement something that will never be in production somewhere or useful to anybody purely for the learning experience and challenge of it.

[EDIT: spelling]

xixixao• 12 years ago

This snippet from the implementation sheds some light on the origins of Go for me, the mindset from which it's born and why it isn't a language for me.

    interactive := false
    if name == "-" {
        interactive = true
        fd = os.Stdin
    } else {
        interactive = false
        fd, err = os.Open(name)
    }

Or do you think I am reading into it too much?

xtacy• 12 years ago

Could you explain why that snippet makes you decide that way?

parktheredcar2• 12 years ago

Does anybody have suggestions for sources of software / computing / codecasting related videos similar to this? Something to put on in the background while working?

TOPLAP (http://toplap.org/) is a decent example of this but they are focused on audio/visual entertainment only.

Basically I'm looking for Twitch for programmers.

arobertson• 12 years ago

A couple links I have stashed: http://coderstv.com/ http://confreaks.com/ http://www.dotconferences.eu/ http://brikis98.blogspot.com/2014/05/must-see-tech-talks-for...

parktheredcar2• 12 years ago

These are some great resources! Thanks.

Implementing a bignum calculator – Rob Pike [video]

Related Stories