mbivert (u/mbivert) - Readit News

mbivert commented on Lambda Calculus in 383 Bytes (2022) justine.lol/lambda/... · Posted by u/MrBuddyCasino

jart · 7 months ago

I never would have been able to understand lambda calculus well enough to write the blog post if I started with [0]. I say just pull out the shell and start coding things. Then read [0] later to appreciate things on a deeper level.

mbivert · 7 months ago

I think I must agree: while I went through [0] to build a λ-calculus interpreter, I already had a fair amount of practice with Church encoding (list, bool, int) using an arbitrary functional language, which retrospectively must have helped greatly to make Selinger's notes clearer.

mbivert commented on Lambda Calculus in 383 Bytes (2022) justine.lol/lambda/... · Posted by u/MrBuddyCasino

Joker_vD · 8 months ago

Does anyone have a gentle introduction on binary λ-calculus? I've tried reading other pages on this site but it goes a bit too fast for me understand what the hell is going on with it.

mbivert · 7 months ago

In case the other answers aren't sufficient, the first step is to understand the λ-calculus[0]. Then, De Bruijn indices[1]. Now, observe that the language we have only has (you need familiarity with the λ-calculus to understand those terms (… pun unintended)) 1/ applications, 2/ abstractions, 3/ integers representing variables [introduced by abstractions]. For example:

    (λ (λ 1 (λ 1)) (λ 2 1))

Binary λ-calculus is then merely about finding a way to encode those three things in binary; here's how the author does it (from the blog post):

    00      means abstraction   (pops in the Krivine machine)
    01      means application   (push argument continuations)
    1...0   means variable      (with varint de Bruijn index)

The last one isn't quite clear, but she gives examples in `compile.sh`:

      s/9/11111111110/g
      s/8/1111111110/g
      s/7/111111110/g
      s/6/11111110/g
      s/5/1111110/g
      s/4/111110/g
      s/3/11110/g
      s/2/1110/g

To check your understanding, you may want to try to manually convert some λ-expressions using those encoding rules, starting with simple ones, and check what you have with what `compile.sh` yields.

[0]: https://www.irif.fr/~mellies/mpri/mpri-ens/biblio/Selinger-L...

[1]: https://en.wikipedia.org/wiki/De_Bruijn_index

mbivert commented on Picasso was suspected of stealing the 'Mona Lisa' newyorker.com/magazine/20... · Posted by u/bookofjoe

mbivert · 8 months ago

Enjoyable news format; the drawings are a bit crude, not that much considering we're talking about Picasso, but it's more pleasant to read, on a screen, than pure text.

mbivert commented on Mistakes engineers make in large established codebases seangoedecke.com/large-es... · Posted by u/BerislavLopac

protonbob · 8 months ago

I don't have a real critique because I don't have that many years in a codebase the size of OP (just 2). But I struggle with the advice to not try and make a clean section of the code base that doesn't depend on the rest of the application.

Isn't part of good engineering trying to reduce your dependencies, even on yourself? In a latter part of the post, OP says to be careful tweaking existing code, because it can have unforeseen consequences. Isn't this the problem that having deep vertical slices of functionality tries to solve? High cohesion in that related code is grouped together, and low coupling in that you can add new code to your feature or modify it without worrying about breaking everyone else's code.

Does this high cohesion and low coupling just not really work at the scale that OP is talking about?

mbivert · 8 months ago

I think the gist of it is humility: as a newcomer, you don't really know what's out there and why, and there are often good reasons for things to be how they are. Not always, but often enough for avoiding being too original to be favored. This doesn't imply relinquishing on "good engineering habits" either.

Now, once you have a deeper understanding of the codebase, you'll know when and why to break away from existing patterns, but in the beginning phase, it's a good habit to start by learning carefully how things are designed and why.

mbivert commented on Ending our third party fact-checking program and moving to Community Notes model about.fb.com/news/2025/01... · Posted by u/impish9208

mbivert · 8 months ago

Stumbled upon this yesterday or so:

https://www.youtube.com/watch?v=eZlbQqXBsn0

« I think one of the troubles of the world has been the habit of dogmatically believing something or other and I think all these matters are full of doubt and the rational man will not be too sure that he's right; I think we ought always to entertain our opinions to some measure of doubt » (Russel)

mbivert commented on Why Canada Should Join the EU economist.com/europe/2025... · Posted by u/gpi

zapperdulchen · 8 months ago

Many perceive EU laws as imposed without democratic oversight, but this isn't quite accurate. The European Parliament, elected by EU citizens, is involved in most legislative processes. The EU Council, made up of ministers from elected governments, also plays a key role. It's not how national democracies work, but with no unified European public, this system might be the best compromise for now.

mbivert · 8 months ago

Let's look in practice[0]: there's 720 seats in total for 2024. France has 81, spread on its local political spectrum [1]; biggest group has 18 seats. So while there's some democratic oversight, the public perception remains reasonable: the representative weight of an individual is severely diluted (divide & conquer, yada yada).

As it plays on the democratic oversight perception as well, we could also look at the perception/quality of the locally elected bodies, and their general attitude towards the UE: a great example is [2] ("let's ask the people but do it anyway").

That's to say, I believe there are good reasons for people to perceive EU laws as imposed without democratic oversight. It's not 100% true, but overall, it's not an unfair qualification either.

[0]: https://www.europarl.europa.eu/infographic/meps-seats/index_...

[1]: https://fr.wikipedia.org/wiki/Liste_des_d%C3%A9put%C3%A9s_eu...

[2]: https://en.wikipedia.org/wiki/2005_French_European_Constitut...

mbivert commented on Why Canada Should Join the EU economist.com/europe/2025... · Posted by u/gpi

gmueckl · 8 months ago

Factually, the claim of complete loss of sovereignty is just dead wrong. This list details the division of responsibilities between the EU and member states: https://commission.europa.eu/about/role/law/areas-eu-action_...

This shows how narrow the responsibilities of the EU actually are.

mbivert · 8 months ago

Strictly speaking, you're correct, but practically speaking, I believe not so much.

For example, France lost a key advantage ("competition rules") with nuclear energy essentially because it was considered unfair to other countries. But energetic independence is fundamental in part to economical independence: it's a key aspect of sovereignty.

Another example would be the Euro ("monetary policy"):

> Give me control over a nation’s currency, and I care not who makes its laws.

Or, the fact that external laws (from the UE) can be applied to member countries without approval from the people is IMO another rather clear form of loss of sovereignty: a considerable amount (~20% for France IIRC) of legislation is imposed by external, un-elected bodies.

mbivert commented on Who can claim Aristotle? aeon.co/essays/dont-cance... · Posted by u/sillybilly

optimalsolver · 9 months ago

Are you kidding me? You think the slaves being worked to death in the Roman silver mines or galley ships had it any better than the ones in the New World? Pre-modern slavery was just as brutal.

You seem curiously attached to the happiness in slavery fantasy.

mbivert · 9 months ago

Let me repeat myself a third and last time: I don't have enough data points to conclude; acquisition of enough data points to reach a honest opinion is to daunting of a task.

It's not because I don't share your viewpoint that I share its exact opposite either.

mbivert commented on Who can claim Aristotle? aeon.co/essays/dont-cance... · Posted by u/sillybilly

optimalsolver · 9 months ago

You might want to look up the death rate of slaves in Brazil, Chile, Haiti, and most of the New World. You'll be rethinking your entire thesis.

mbivert · 9 months ago

I think you're missing the point.

Slavery is an old thing[0]. Even assuming the death rates are correct, one can't honestly conclude that what happened in the West in the past 500 years is similar to what happened, say, in Antiquity in the West[1] - and that's what most relevant to Aristotle - or amongst ancient Jews[2].

I know that there are too many unknowns for me to even have a clear thesis to begin with.

[0]: https://en.wikipedia.org/wiki/Slavery#History

[1]: https://en.wikipedia.org/wiki/Slavery_in_antiquity

[2]: https://en.wikipedia.org/wiki/Jubilee_(biblical)

mbivert commented on Who can claim Aristotle? aeon.co/essays/dont-cance... · Posted by u/sillybilly

optimalsolver · 9 months ago

> from a cost-effectiveness point of view

What's the cost-effectiveness of a master selling one of his female slave's children away from her, which was a regular occurrence?

mbivert · 9 months ago

I meant in general: I'd expect moderately happy slaves to perform better, and the cost of keeping them moderately happy lower than acquiring new slaves over and over; creating slaves has a cost.

Accurately answering your question requires writing a thesis: one needs extensive access to accurate data spanning thousands of years, a solid grasp of history, psychology, ancient customs, etc. Those situations are full of subtle nuances; what historians currently understand might not even be that accurate.

OTOH, casting reasonable doubts by assuming a fair amount of people weren't too stupid is less bold of a position than "slave owners were living devil", but at least it's honest.

(Which doesn't imply that "slave owners were living devil" isn't true, merely that it's dishonest to say that it's true, because it's too difficult to know for sure).