morning

I've now gotten to the point where all I see reading Clojure code is a sea of type errors.

@martintrojer: time to move on…. start using Haskell and tell us what it is like on the other side

@thomas: http://martintrojer.github.io/beyond-clojure/2016/04/21/beyond-clojure-haskell

I’m enjoying being back in clojure-land for a bit - all I see is “stuff I won’t be able to do next time I’m forced back to a strongly typed language” 🙂

well, “forced back to Java or C#” is probably more accurate

Never had the joy of using a properly typed language in a professional environment.

@korny: what sort of stuff dyu mean ?

Java, C# doesn't make it onto my list.

- Read in config as a map of stuff, some list some sets some vectors, then extract stuff from it as needed

- Merge two config maps, with custom rules about what to do when keys are in both

- Subscribe to a JMS queue, on each message try parsing it as an Int (which is expected) and conj it onto a list (in an atom). However, if I get something that isn’t an int, log it and conj it onto the list anyway, something later can handle errors for me.

surely you can do all that in a typed language, with appropriate use of sum or tagged types, or writers or whatever ? ?

You definitely can - but you would spend an age writing all those types. And you could only do it in a “good” typed language, which narrows the field a lot.

i guess the deal you are making is that you spend the time on defining types beforehand in exchange for not spending time hunting down bugs later

Yep - feels like premature optimisation to me. I don’t actually get very many type bugs. The ones I do get are generally short-lived - mistakes made during coding or refactoring - and even rudimentary unit/integration tests catch them.

This is all a matter of personal preference of course 🙂

type bugs are a wide net for me. all the nil stuff, shape errors, keyword typos etc

could be - i can't judge - i haven't done a significant project in a language with a powerful type system - i would definitely like to

event side-effect bugs are type errors in my book

(since side effects clearly should be part of the type signature)

The closest I’ve done was Scala - and yes, there are things I miss from there. Type-based pattern matching, and type-safe Options (maybe monad) were great. Maybe I just haven’t spent enough time in “good” languages 🙂

Yeah, people who say types are bad since they wasted too many years in Java doesn't know the whole story.

Everybody needs to write an parser in Parsec and experience the week-long grin when the Applicative Functor penny drops.

The flip side is people who say “types are awesome” and then don’t offer up a language that implements them properly that is widely used enough for us to get paid using it 🙂

@korny s/types/lisps/g 😉

Generative testing is another thing I’d love to play with properly, if I were using a “good” typed language - I’ve seen some magic testing done in Haskell. I’ll be interested to see how well they work with spec - haven’t had a chance to play yet.

schema can also output generators

... nothing new here

Can it? Cool.

yes, learning Haskell properly is on the list of things to do.. maybe one day.

I’ve found generative testing difficult to use effectively for “business rules"

I expected it to be really useful for testing validation rules, but had difficulty expressing good properties

… except of course, last time I asked a Haskell fan “can the type system do X” they said “ah, no, Haskell’s type system is not up to it, you should be using Idris” 😉

what was X @korny ? was it a dependent type thingy ?

I can’t really remember - it was a while ago, sorry.

Anyone here worked through this book before? (https://www.packtpub.com/big-data-and-business-intelligence/clojure-data-science)

@yogidevbear: ask @otfrom I think Henry Garner works for Mastodon C.

actually that might mean a very biased opinion...

We are working through it slowly in book club at work. We like it.

i read half of it (before i joined mastodonC), and found it very interesting. It is quite a bit of work though!

whether that is less biased i'll leave to you to decide

I did find that once i got used to the format i could use it more as a reference when i got stuck doing stuff

Thanks for the feedback. How did you find the mathematical formula stuff? This is the part I think I'm most interested in. Is it easy to follow and learn with no prior experience?