dry-rb/chat

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Jules Ivanic

@guizmaii

Hi everyone,

First, I want to thanks all of the people working on this project ! It’s an awesome project ! :clap:

Second, is there any .sequence method proposed in dry-rb ?

sequence signature is: F[G[A]] -> G[F[A]]

Nikita Shilnikov

@flash-gordon

@guizmaii called w/o a block traverse acts as sequence https://github.com/dry-rb/dry-monads/blob/master/lib/dry/monads/list.rb#L263-L286

Jules Ivanic

@guizmaii

ok thanks :)

Jules Ivanic

@guizmaii

does it work on Ruby Array ?

Nikita Shilnikov

@flash-gordon

nope, we don't monkey patch core classes, it's against our philosophy :)

Jules Ivanic

@guizmaii

awesome philosophy !

Jules Ivanic

@guizmaii

Do you thinks that this make sense: atomic_rows = Concurrent::AtomicReference.new(Dry::Monads::List.[]) ?

I need to update this list but my computation is parrallel

I’m very new to concurrency in Ruby :/

hum maybe this is better:

future_rows = Dry::Monads::List.[]
requests.find_in_baches { |data|
  future_rows += Task[:io] { compute_rows(data) } 
}

future_rows.traverse { |rows|
  …
}

WDYT ?

Nikita Shilnikov

@flash-gordon

future_rows = Concurrent::Array.new
requests.find_in_baches { |data|
  future_rows << Task[:io] { compute_rows(data) } 
}

Dry::Monads::List.coerce(future_rows.to_a).traverse { |rows|
  …
}

@guizmaii I think this one will work better

as in Monads::List isn't meant to be mutable

and, actually, you can use future_rows = []

since it's mutated from the same thread

Jules Ivanic

@guizmaii

Hum you’re right ! Thanks :)

is it coslty to coerce ?

if the array contains a lot of elements (< 100.000)

Nikita Shilnikov

@flash-gordon

not really

O(n) max

you can do List.new, it's O(1)

I bet traversing will be way more expensive tbh, it's not omptimized for long lists

otoh, it can be not that bad

Nikita Shilnikov

@flash-gordon

btw, if you use find_in_batches then future_rows.size will be equal total_rows / batch_size

which is better

I think you should give it a chance and see if something can be improved later

Jules Ivanic

@guizmaii

ok thanks for your precise answers ! :)

Jules Ivanic

@guizmaii

This message was deleted

Jules Ivanic

@guizmaii

result: https://twitter.com/guizmaii/status/1070020900752384001

Thanks for your help @flash-gordon ! 🙂

Nikita Shilnikov

@flash-gordon

sure, np

Grant Shangreaux

@gcentauri

is it counterproductive to add methods to structs? i'm primarily thinking of predicate type methods that would only return true or false based on the data the struct is holding

like, if i had a struct Fruit and if its name field was "banana" then my_fruit.banana? would return true. or... should there be helper functions like is_banana?(fruit)

Nikita Shilnikov

@flash-gordon

I do have a few methods like this, don't see anything harmful since it's not the same as having an AR-model :)

Grant Shangreaux

@gcentauri

haha thanks

ruby often feels like a slippery slope to me in those regards

Jules Ivanic

@guizmaii

Hi everyone,

I’m using the Task monad and I saw that there’s a pure function but there’s not its “dual” failed (equivalent of Concurent::Promise.reject).

How would you implement it ?

I don’t want to throw exception. Just create an immedialty failed Task

(throwing is expensive in JRuby)

is this something sensible:

    def failed(error)
      Dry::Monads::Task.new(Concurrent::Promise.reject(error))
    end

???

This message was deleted

Nikita Shilnikov

@flash-gordon

@guizmaii yeah, we should have it, no particular reason we don't have, just no one asked for it

Jules Ivanic

@guizmaii

If I have time I’ll push you a PR

Nikita Shilnikov

@flash-gordon

:+1:

Jules Ivanic

@guizmaii

def failed(error, &block) signature looks ok for you ? With the same Undefined trick as in pure ?

Nikita Shilnikov

@flash-gordon

not sure because answering this question would pre-emptying my current brain stack :)

Jules Ivanic

@guizmaii

k. We’ll talk about that around a good old PR so

Tonni Tølbøll Lund Aagesen

@ta

Hello, How do I get transform_keys(&:to_sym) to work with nested structs? It works fine with 1st level attributes.

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