cats VS talk-transcripts

A functional programming library: https://typelevel.org/cats/

Learn something that pays the bill first - nowadays it's Golang/Rust react/typescript. Then you can try some pure fp libs like fp-ts and fp-core.rs, and look through existing scala cats docs. If you'll feel bad about it - that's totally fine and expectable, fp takes a paradigm shift and not that many dev able to shift their brains way of thought due to basic psychological rigidity) (inability to change habits and to modify concepts/attitudes once developed). And that's purely a staffing and management issue - folks hired randoms out of the blue, and called 'em a team.

I'm sorry, but have you ever done functional programming for a real company, like in a functional programming language like Haskell, Scala, or F#? Have you ever used Scala cats or scalaz? Have you ever learned category theory and how to apply its abstractions in software? Listen u/judethedude2106 this person hasn't gone as far down the functional programming rabbit hole as I have. Beyond learning the basics like the difference between pure and impure functions, what are closures, what higher order functions are and the most common ones like .map, .filter, and .flatmap, the immutable collections like immutable linked lists and trees, and what a Monad is and common monads like those used for futures/promises, async programming, and Option (Some or None, which is used instead of null checking), the more advanced functional programming stuff like category theory based abstractions are totally useless for real jobs and is just a giant time suck. Don't waste years on functional programming, spend at most a few months on it and no more.

As a former functional programmer in Scala, please do not go deep into the Category Theory programming. Scala has libraries like this one called "Cats", a cute shortened name for "Category Theory", but code that makes heavy use of these constructs is not understandable to other programmers. Other than using Monads as a design pattern for things like Options (which can be "Some" or "None"), Futures or Promises (which is used for asynchronous programming), and a few other things, please do not make heavy use of category theory constructs in real programming projects that will have other developers working on them. It is a rabbit hole that may be fun but is not super practical. Sure, write pure functions without side effects, but do not use the words "Bimonad", "Invariant Monoidal", and "Semigroup" in your code. The most common, practical application/use of functional programming is basic things like closures, .map, .filter, maybe chaining maps with like a .flatmap or whatever your programming language uses instead of chain or flatmap, and SQL that uses keywords like WHERE which can be represented in code by using a call to .filter. Like the place where these constructs are used most is in data processing like with SQL, ETL (Extract Transform, Load) jobs, Java's MapReduce on Hadoop, Scala's Apache Spark, and other data processing type things. Haskell is not a popular programming language in real world projects for a number of reasons and one of them is the heavy and sometimes impractical use of Category Theory.

At a previous job of mine we actually had an entirely pure Scala ecosystem using cats which instead uses typeclasses, referential transparency, and other FP concepts as the foundations for how to code. So a lot of flexibility to the language.

Thanks! It's used heavily here

I did work in Scala for a few years. We employed Cats[1], and even a bit of Matryoshka[2] though most of the work I do today is in Python.

Nowadays I think about computational requirements in terms of relations among behavioral dependencies. Like, "I want to perform operation O on input A and return a B. To do this, I'll need a way to a -> b and a way to b -> b -> b." I often pass these behavioral dependencies in as arguments and it tends to make the inner core of my programs pretty abstract and built up as layers of specificity.

Zooming out nearly all the way, it makes me feel tethered in a qualitatively unique way to certain deep truths of the universe. In a Platonic sense, invoking certain ideas like a monad make me feel like I'm approaching the divine or at least one instantiation of a timeless universal that operates outside of material existence.

I'd imagine some mathematicians might see the universe in a similar way - one where immortal relations between ontological forms exist beyond time and space and at the same time can be threaded through the material world by intellectual observation and when those two meet a beautiful collision occurs.

1. https://typelevel.org/cats/

2. https://github.com/precog/matryoshka

Our second type class example attempted to illustrate one last perk: type safety at compile time. It did so with a simplified example of the cats core library for type safety equality comparison between objects. If you're not familiar with cats, go ahead and give it go.

Thank you for this recommendation. I've never heard of it before and now I'm reading: https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

It's giving me energy this Monday holiday(USA)!

race?

> [Audience reply: Sprinter]

> Right, only somebody who runs really short races, okay?

> [Audience laughter]

> But of course, we are programmers, and we are smarter than runners, apparently, because we know how to fix that problem, right? We just fire the starting pistol every hundred yards and call it a new sprint.

https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

>So this is 10x, a full order of magnitude reduction in (?) severity before we get to the set of problems I think are more in the domain of what programming languages can help with, right? And because you can read these they'll all going to come up in a second as I go through each one on some slide so I'm not going to read them all out right now. But importantly there's another break where we get to trivialisms of problems in programming. Like typos and just being inconsistent, like, you thought you're going to have a list of strings and you put a number in there. That happens, you know, people make those kinds of mistakes, they're pretty inexpensive.

[0] Video: https://www.youtube.com/watch?v=2V1FtfBDsLU

[1] Slides and transcript: https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

[2] Video https://www.youtube.com/watch?v=YR5WdGrpoug

[3] Slides and transcript https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

This is tangentially related to Puzzles-vs-Problems in Rich Hickey's Effective Programs

> Eventually I got back to scheduling and again wrote a new kind of scheduling system in Common Lisp, which again they did not want to run in production. And then I rewrote it in C++. Now at this point I was an expert C++ user and really loved C++, for some value of love. But as we'll see later I love the puzzle of C++. So I had to rewrite it in C++ and it took, you know, four times as long to rewrite it as it took to write it in the first place, it yielded five times as much code and it was no faster. And that's when I knew I was doing it wrong.

[...]

> So I mean for young programmers, if everybody's tired and old, this doesn't matter any more. But when I was young, when I was young, I really, you know, when you're young you've got lots of free space. I used to say "an empty head", but that's not right. You've got a lot of free space available and you can fill it with whatever you like. And these type systems they're quite fun, because from an endorphin standpoint solving puzzles and solving problems is the same, it gives you the same rush. Puzzle solving is really cool. But that's not what it should be about.

Talk: https://www.youtube.com/watch?v=2V1FtfBDsLU

Slides and transcript: https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

Using triggers + history tables (aka audit tables) is the right answer 98% of the time. Just do it. If you're not already doing it, start today. It is a proven technique, in use for _over 30 years_.

Here's a quick rundown of how to do it generically https://gist.github.com/slotrans/353952c4f383596e6fe8777db5d... (trades off space efficiency for "being easy").

It's great if you can store immutable data. Really, really great. But you _probably_ have a ton of mutable data in your database and you are _probably_ forgetting a ton of it every day. Stop forgetting things! Use history tables.

cf. https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

Do not use Papertrail or similar application-space history tracking libraries/techniques. They are slow, error-prone, and incapable of capturing any DB changes that bypass your app stack (which you probably have, and should). Worth remembering that _any_ attempt to capture an "updated" timestamp from your app is fundamentally incorrect, because each of your webheads has its own clock. Use the database clock! It's the only one that's correct!

Rich Hickey (creator of Clojure) references Polya several times in his classic talk "Hammock Driven Development". Here's a transcript:

https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

I've long been impressed by Hickey's problem solving skills, so I took much of this talk to heart, and even bought a copy of HTSI. Can't say it really helped me any more than Rich's talk (as a programmer) but I'm thinking I'll give it another look.

>Great product designs require no manual, and similarly, great interfaces need no documentation. Imagine having to read a manual on how to use a coffee mug.

This could not be more wrong.

Not everything is easy. If a library is addressing a complicated domain, solving by definition a complicated problem, it is fine if it requires some learning.

When did expertise and learning become bad things? If software is an engineering discipline, why would people in it ever promulgate the idea that any random cog can step in to any “engineer”s shoes?

Rich Hickey analogizes this mentality to the world of music, where it taken for granted that learning an instrument requires a lot of study:

“ We start with the cello. Should we make cellos that auto tune? Like, no matter where you put your finger, it's just going to play something good, play a good note.

“[Audience laughter]

“Like, you're good. We'll just fix that.

“ Should we have cellos with, like, red and green lights? Like, if you're playing the wrong note, you know, it's red. You slide around, and it's green. You're like, great! I'm good. I'm playing the right song. Right?

“ Or maybe we should have cellos that don't make any sound at all. Until you get it right, there's nothing.

“ [Audience laughter]”

https://github.com/matthiasn/talk-transcripts/blob/master/Hi...

You might find adjacent talks and speakers here ... https://github.com/matthiasn/talk-transcripts

Many languages merge the two concepts, and implement procedures as functions that return void. This may muddle/complect their distinction, causing programmers to call procedures from within functions, thereby making those functions into impure functions (meaning that they affect the world outside of themselves, through side-effects like I/O or mutating state). This should be avoided, especially if you care about debug-ability and Functional Core, Imperative Shell architectures (see Gary Bernhardt's Boundaries talk at 31:56) (which make testing your system easier, without mocking).

A great way to do this in practice is to write design docs. I take an approach inspired by Rich Hickey's "Hammock Driven Development" - identify the problem, state it, write it down - describe what you know about it - try to describe what you know that you don't know about it - list the constraints your solution has to operate within - enumerate some potential solutions and explore their problems - (later) choose a path, and describe why it was chosen over the alternatives