Add Functional Programming - Generics as Type Classes #249

jhwgh1968 · 2021-03-27T21:06:54Z

I put this under functional languages, since it is really an example of the concept of "type classes" in Rust. If this specific example is more of a design pattern, I would be happy to move it.

If no one beats me to it, I should be able to fix the two FIXMEs at the bottom sometime next week.

jhwgh1968 · 2021-03-27T21:08:55Z

Hmm, the errors seem to be caused by broken links. I thought relative links would work in mdbook.

Any guidance on how to fix those?

simonsan

I think it's just that the patterns subdirectory was missing

functional/stateful-types.md

simonsan · 2021-03-28T05:31:24Z

This is related to #100 isn't it? Maybe you can take the links from there, I posted some articles in it, that describe the pattern.

jhwgh1968 · 2021-03-28T15:07:09Z

Thanks, @simonsan. I actually missed that PR somehow.

I have added the bottom of the two links you mentioned. Now my question is, how do I break up the link for the hard wrap limit? It is longer than 80 characters by itself.

functional/stateful-types.md

simonsan · 2021-03-28T16:49:40Z

Maybe this one is also a nice addition to Read More:
https://web.archive.org/web/20210328164854/https://rustype.github.io/notes/notes/rust-typestate-series/rust-typestate-index

jhwgh1968 · 2021-03-29T00:38:45Z

The second link makes sense to me, @simonsan, and seem to cover the type theory in more depth. I also put in a small wording change to be more precise, and helpful if people Google this.

I think it's a solid first version that is ready to merge, unless you have other additions.

simonsan · 2021-03-29T06:53:03Z

The second link makes sense to me, @simonsan, and seem to cover the type theory in more depth. I also put in a small wording change to be more precise, and helpful if people Google this.

I think it's a solid first version that is ready to merge, unless you have other additions.

I need to give it a full read still, haven't completely reviewed it due to time constrains and just helped you fix the CI tests. Will take care of it the next two days. Cheers.

functional/stateful-types.md

simonsan

@marcoieni @pickfire Want to give it a read as well?

marcoieni · 2021-03-30T13:15:49Z

functional/stateful-types.md

+
+Here is what that looks like:
+
+```rust,ignore


I would prefer to remove this ignore flag, even if it requires copy pasting from previous code blocks.
What other people think about this?

Could be nice to have a working example here, indeed. So people can copy and paste it and try it out/play around with it.

I only did that to avoid repeating all the typing. I can easily put that back in and make it work.

Hmm, this is turning out to be trickier than I thought. I may have to refactor the example to make it simple enough. That will take me a bit.

If you want to you can do that in another PR as well (regarding removing the ignore). It would be nice to have a working example that is checked, but not always necessary. Also this is quite complex so I'm fine with just refactoring it at a later stage, maybe even by someone else. @marcoieni thoughts?

It's up to jhwgh. If you want you can do it in another PR :)

marcoieni · 2021-03-30T13:25:25Z

What's the advantage of using this approach for state machines with respect to the one covered by the rust book ?

jhwgh1968 · 2021-03-31T04:00:46Z

The main advantage over the book, @marcoieni, is that this allows for shared data and IMO more readable shared impls.

I will type up that explanation in the PR.

functional/stateful-types.md

simonsan · 2021-04-01T12:29:26Z

functional/stateful-types.md

+
+Here is what that looks like:
+
+```rust,ignore


If you want to you can do that in another PR as well (regarding removing the ignore). It would be nice to have a working example that is checked, but not always necessary. Also this is quite complex so I'm fine with just refactoring it at a later stage, maybe even by someone else. @marcoieni thoughts?

functional/stateful-types.md

pickfire · 2021-04-01T16:33:57Z

functional/stateful-types.md

+    interp.compile_script("print('2 + 2')").unwrap();
+    interp.exec().unwrap();
+}
+```


Example seemed complicated. If someone like me who had no experience with state machine, this will be hard to understand. Just wondering could there be a simpler example?

Say, empty letter -> written letter -> closed letter?

pickfire · 2021-04-01T16:35:50Z

functional/stateful-types.md

+struct Interpreter<S: State> {
+    // same fields for execution, but now add:
+    state_data: S,
+}


Seemed extra to me. Why not just Interpreter -> LoadedInterpreter -> ReadiedInterpreter or something similar since they won't share common stuff?

Or maybe this is just to show <S: State>? Or maybe we can show both methods.

pickfire · 2021-04-01T16:38:15Z

functional/stateful-types.md

+
+```rust,ignore
+fn main() {
+    let mut interp = Interpreter::<Init>::default().init();


Having this turbofish is the downside of what I mentioned. Not ergonomics and what if user does Interpreter::<Loaded>::default() instead? At least default isn't there in this case which is safe.

The default only being in the init state is precisely what I intended, for that exact reason.

I agree it's clunky, but also I think it's reasonable to recomment. If you don't put the turbofish in at all, I think the current stable has a good suggestion to lead you in the right direction.

Co-authored-by: Marco Ieni <[email protected]>

jhwgh1968 · 2021-04-11T16:16:42Z

I have a couple more review comments to go, but I am getting close.

Can you specify that with code size we mean the size of the binary?

Done.

Also please, do not force push. It's easier for us to see what changes from review to review.
Everything will be squashed in one commit anyway when we merge this.

On other PRs I saw maintainers doing "merge commits" with master, which usually creates a giant mess in git. I will keep that in mind that you always squash, and not worry about it.

The problem is that mdbook automatically adds fn main() { } around everything because it doesn't exist.

Ah, that makes sense. I will fix it.

jhwgh1968 · 2021-04-11T16:27:30Z

The main function I added to the compiling example is currently empty. I am planning to put in a simple example of using the types, but I will have to think about it (because construction is something I skipped over).

marcoieni · 2021-04-11T17:34:28Z

On other PRs I saw maintainers doing "merge commits" with master, which usually creates a giant mess in git. I will keep that in mind that you always squash, and not worry about it.

We set this in December:

I have a couple more review comments to go, but I am getting close.

Yes, you are! 💪

functional/generics-type-classes.md

Co-authored-by: Marco Ieni <[email protected]>

simonsan · 2021-04-11T23:48:01Z

Cool! I'll also read through it again in the next days. <3

marcoieni

This is great! I approved it. simonsan, merge this if it looks good to you once you have read it :)

marcoieni · 2021-04-15T17:58:22Z

The CI is failing for reasons unrelated to this PR:

jhwgh1968 · 2021-04-16T00:59:13Z

Thanks, @marcoieni! I unfortunately could not think of an easy constructor for main, but I think this example is clear enough as it is.

functional/generics-type-classes.md

simonsan · 2021-04-16T09:14:18Z

Nice, thank you! :)

simonsan reviewed Mar 28, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

simonsan added C-addition Category: Adding new content, something that didn't exist in the repository before A-functional Area: Content about Functional Programming A-pattern Area: Content about Patterns labels Mar 28, 2021

jhwgh1968 force-pushed the state_pattern branch 2 times, most recently from f41f78b to 8a48392 Compare March 28, 2021 15:04

simonsan reviewed Mar 28, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

simonsan reviewed Mar 28, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

simonsan reviewed Mar 28, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

simonsan mentioned this pull request Mar 28, 2021

Create typestate.md #100

Draft

simonsan reviewed Mar 28, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

simonsan reviewed Mar 29, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

simonsan previously approved these changes Mar 29, 2021

View reviewed changes

marcoieni reviewed Mar 30, 2021

View reviewed changes

jhwgh1968 dismissed simonsan’s stale review via dc4ab22 March 31, 2021 04:20

jhwgh1968 force-pushed the state_pattern branch from 7bef713 to dc4ab22 Compare March 31, 2021 04:20

simonsan requested changes Apr 1, 2021

View reviewed changes

pickfire reviewed Apr 1, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

pickfire reviewed Apr 1, 2021

View reviewed changes

functional/stateful-types.md Outdated Show resolved Hide resolved

pickfire reviewed Apr 1, 2021

View reviewed changes

jhwgh1968 and others added 5 commits April 11, 2021 11:03

Fix some review comments

fe990c4

Fix footnotes

b77406a

Co-authored-by: Marco Ieni <[email protected]>

Fix hard tabs

26932d1

Remove extra blank line

abdf5a6

Fix some review comments

f7f57fc

jhwgh1968 added 4 commits April 11, 2021 11:18

Grammar fix

f0f2aa3

Expand Nfs into typed struct

e2845c6

Add empty main to satisfy mdbook

59129ca

Add blanks for readability

6a0717e

marcoieni reviewed Apr 11, 2021

View reviewed changes

functional/generics-type-classes.md Outdated Show resolved Hide resolved

marcoieni reviewed Apr 11, 2021

View reviewed changes

functional/generics-type-classes.md Outdated Show resolved Hide resolved

jhwgh1968 and others added 2 commits April 11, 2021 19:29

Typo fix

6a51c69

Co-authored-by: Marco Ieni <[email protected]>

Typo fix

cd0150c

Co-authored-by: Marco Ieni <[email protected]>

Merge branch 'master' into state_pattern

c2ca3e9

marcoieni previously approved these changes Apr 15, 2021

View reviewed changes

simonsan reviewed Apr 16, 2021

View reviewed changes

functional/generics-type-classes.md Outdated Show resolved Hide resolved

Update functional/generics-type-classes.md

86bb005

simonsan dismissed marcoieni’s stale review via 86bb005 April 16, 2021 09:13

simonsan approved these changes Apr 16, 2021

View reviewed changes

simonsan merged commit 680509a into rust-unofficial:master Apr 16, 2021

jhwgh1968 deleted the state_pattern branch November 27, 2022 15:12

jhwgh1968 restored the state_pattern branch November 27, 2022 15:13

jhwgh1968 deleted the state_pattern branch November 27, 2022 15:22

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Add Functional Programming - Generics as Type Classes #249

Add Functional Programming - Generics as Type Classes #249

jhwgh1968 commented Mar 27, 2021

jhwgh1968 commented Mar 27, 2021

simonsan left a comment

simonsan commented Mar 28, 2021

jhwgh1968 commented Mar 28, 2021

simonsan commented Mar 28, 2021

jhwgh1968 commented Mar 29, 2021

simonsan commented Mar 29, 2021

simonsan left a comment

marcoieni Mar 30, 2021

simonsan Mar 30, 2021

jhwgh1968 Mar 31, 2021

jhwgh1968 Mar 31, 2021

simonsan Apr 1, 2021 •

edited

Loading

marcoieni Apr 1, 2021

marcoieni commented Mar 30, 2021

jhwgh1968 commented Mar 31, 2021

simonsan Apr 1, 2021 •

edited

Loading

pickfire Apr 1, 2021

pickfire Apr 1, 2021 •

edited

Loading

pickfire Apr 1, 2021 •

edited

Loading

jhwgh1968 Apr 1, 2021

jhwgh1968 commented Apr 11, 2021 •

edited

Loading

jhwgh1968 commented Apr 11, 2021 •

edited

Loading

marcoieni commented Apr 11, 2021 •

edited

Loading

simonsan commented Apr 11, 2021

marcoieni left a comment

marcoieni commented Apr 15, 2021 •

edited

Loading

jhwgh1968 commented Apr 16, 2021

simonsan commented Apr 16, 2021

Add Functional Programming - Generics as Type Classes #249

Add Functional Programming - Generics as Type Classes #249

Conversation

jhwgh1968 commented Mar 27, 2021

jhwgh1968 commented Mar 27, 2021

simonsan left a comment

Choose a reason for hiding this comment

simonsan commented Mar 28, 2021

jhwgh1968 commented Mar 28, 2021

simonsan commented Mar 28, 2021

jhwgh1968 commented Mar 29, 2021

simonsan commented Mar 29, 2021

simonsan left a comment

Choose a reason for hiding this comment

marcoieni Mar 30, 2021

Choose a reason for hiding this comment

simonsan Mar 30, 2021

Choose a reason for hiding this comment

jhwgh1968 Mar 31, 2021

Choose a reason for hiding this comment

jhwgh1968 Mar 31, 2021

Choose a reason for hiding this comment

simonsan Apr 1, 2021 • edited Loading

Choose a reason for hiding this comment

marcoieni Apr 1, 2021

Choose a reason for hiding this comment

marcoieni commented Mar 30, 2021

jhwgh1968 commented Mar 31, 2021

simonsan Apr 1, 2021 • edited Loading

Choose a reason for hiding this comment

pickfire Apr 1, 2021

Choose a reason for hiding this comment

pickfire Apr 1, 2021 • edited Loading

Choose a reason for hiding this comment

pickfire Apr 1, 2021 • edited Loading

Choose a reason for hiding this comment

jhwgh1968 Apr 1, 2021

Choose a reason for hiding this comment

jhwgh1968 commented Apr 11, 2021 • edited Loading

jhwgh1968 commented Apr 11, 2021 • edited Loading

marcoieni commented Apr 11, 2021 • edited Loading

simonsan commented Apr 11, 2021

marcoieni left a comment

Choose a reason for hiding this comment

marcoieni commented Apr 15, 2021 • edited Loading

jhwgh1968 commented Apr 16, 2021

simonsan commented Apr 16, 2021

simonsan Apr 1, 2021 •

edited

Loading

simonsan Apr 1, 2021 •

edited

Loading

pickfire Apr 1, 2021 •

edited

Loading

pickfire Apr 1, 2021 •

edited

Loading

jhwgh1968 commented Apr 11, 2021 •

edited

Loading

jhwgh1968 commented Apr 11, 2021 •

edited

Loading

marcoieni commented Apr 11, 2021 •

edited

Loading

marcoieni commented Apr 15, 2021 •

edited

Loading