Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Rust, Macros, λ-calculus/Church numerals, oh my

github.com

Post reply on HN
Print view View original

11–20 of 82 posts

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#11

Post by db48x »

ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

I disagree. I looked through the source code to Principia a while back, and it makes really effective use of Greek script, black-letter script, math symbols, etc for implementing a physics engine. (It's a mod for Kerbal Space Program that implements n-body gravitation.) It's really well written and used just enough to make things more understandable. (They've got a great units system too; it's worth reading the code just for that.) Here's a random selection: https://github.com/mockingbirdnest/Principia/blob/master/phy...

Like anything else, it can certainly be misused. That doesn't mean it's never worth using though.

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#12

Post by _emacsomancer_ »

llamathrowaway wrote: post #4
ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

Maybe it’s time for a plugin that does this (or maybe it already exists?): You press the backslash key, enter the name of the symbol, then press enter, and the symbol will show up in your buffer. Something like: \lambda -> λ \Lambda -> Λ \\ -> \ et cetra.

xcompose does something like that. (as does TeX for that matter, in a different fashion.)

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#14

Post by frosted-flakes »

llamathrowaway wrote: post #4
ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

Maybe it’s time for a plugin that does this (or maybe it already exists?): You press the backslash key, enter the name of the symbol, then press enter, and the symbol will show up in your buffer. Something like: \lambda -> λ \Lambda -> Λ \\ -> \ et cetra.

A dedicated global compose key solves this problem very elegantly. Hitting the ◆ compose key (right alt for me) followed by a series of intuitive characters inserts the corresponding character.

For example:

◆ - - - produces an em dash (—)

◆ - - . produces an en dash (–)

◆ ' e produces é

◆ | c produces the cent symbol (¢)

Usually, you can just guess the combination and be right 3/4 times. Otherwise, it's fairly easy to look it up, or create it if it doesn't exist yet.

Some distros of Linux have this built-in, but I use WinCompose[1] on Windows.

[1]https://github.com/samhocevar/wincompose

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#15

Post by whatshisface »

db48x wrote: post #11
ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

I disagree. I looked through the source code to Principia a while back, and it makes really effective use of Greek script, black-letter script, math symbols, etc for implementing a physics engine. (It's a mod for Kerbal Space Program that implements n-body gravitation.) It's really well written and used just enough to make things more understandable. (They've got a great units system too; it's worth reading the code…

Greek letters are good for transcribing equations that were written with Greek letters. The equations were written like that because you only get one letter per variable and you need more than 26 variables across multiple equations, which you want to be consistent. You only get one letter per variable because on paper you write down each equation about fifty times as you work with it, so it's kept short as much as possible.

Unless you speak Greek, I can't think of any other reasons for Greek letters to wander in to code.

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#16

Post by xiphias2 »

llamathrowaway wrote: post #4
ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

Maybe it’s time for a plugin that does this (or maybe it already exists?): You press the backslash key, enter the name of the symbol, then press enter, and the symbol will show up in your buffer. Something like: \lambda -> λ \Lambda -> Λ \\ -> \ et cetra.

Atom in Julia Pro does this (with autocomletion), and I've been using it in practice to clarify math in my code. It's great in practice.

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#17

Post by orbital-decay »

db48x wrote: post #11
ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

I disagree. I looked through the source code to Principia a while back, and it makes really effective use of Greek script, black-letter script, math symbols, etc for implementing a physics engine. (It's a mod for Kerbal Space Program that implements n-body gravitation.) It's really well written and used just enough to make things more understandable. (They've got a great units system too; it's worth reading the code…

>Here's a random selection: https://github.com/mockingbirdnest/Principia/blob/master/phy...

I don't think r² as a variable name is a good idea. It may look natural for some (including myself), but for others it implies a function while not being one.

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#18

Post by nurettin »

ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

I did not know how to produce greek letters until I read your comment and thought: why not just add the greek keyboard layout and press l, p and g?

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#19

Post by jimmy_dean »

whatshisface wrote: post #15
db48x wrote: post #11

Earlier quoted context omitted.

I disagree. I looked through the source code to Principia a while back, and it makes really effective use of Greek script, black-letter script, math symbols, etc for implementing a physics engine. (It's a mod for Kerbal Space Program that implements n-body gravitation.) It's really well written and used just enough to make things more understandable. (They've got a great units system too; it's worth reading the code…

Greek letters are good for transcribing equations that were written with Greek letters. The equations were written like that because you only get one letter per variable and you need more than 26 variables across multiple equations, which you want to be consistent. You only get one letter per variable because on paper you write down each equation about fifty times as you work with it, so it's kept short as much as po…

100% this. To understand code written with Greek letters you'd also need to understand the author's intentions for using said letters. Is mu an average or coeff of friction? Why should I lean on a crutch of context for a casual skim of code? It doesn't help readability and it surely isn't enjoyable to write.

Re: Rust, Macros, λ-calculus/Church numerals, oh my

#20

Post by gylterud »

ajross wrote: post #2

While it's definitely cute and amusing, this is exactly why languages that specify their source code in non-ascii encodings are a bad idea. Fully 92.6% of working programmers have no idea how to produce a λ or γ on their input device of choice. Maybe a third of those could eventually find it with a character picker tool. Java started this (in the unicode era anyway -- yeah yeah, APL). The community quite sanely rejec…

Agda[0] and Coq and other languages for formalising mathematics (they are also programming languages) make a lot of use of Unicode to make the mathematical statements readable. Here is an example:

> ∑-+-distribute : ∑ (A + B) C ≃ (∑ A (C ∘ left)) + (∑ B (C ∘ right))

This is quite readable and would be understandable to someone who did not know Agda or the library in particular, but who understood the subject material. If the characters were replaced by words the overhead would be big.

The Plan9 operating system invented the compose key, which makes writing unicode characters easy enough for anyone to use them. Unfortunately, it requires a bit of setup to make the compose key work in X on Linux or *BSD (I have described th process here[1]). Agda and Coq therefore use special input modes for Emacs and other editors.

I also use Unicode in my Latex documents to make them more readable. [2]

[0]: https://agda.readthedocs.io/en/latest/getting-started/quick-...

[1]: https://hakon.gylterud.net/tutorials/unicode.html

[2]: https://hakon.gylterud.net/tutorials/latex-maths-unicode.htm...

Post reply on HN