heimdell / elm-optics Goto Github PK

Hi, I briefly looked at your package and it seems to be quite similar to https://package.elm-lang.org/packages/arturopala/elm-monocle/latest/. To help people decide which package to use, maybe your readme could have a quick explanation for why or why not to use your package over elm-monocle?

Hi, love the way your lib tackles optics with Elm, especially composition (I'm the guy that wrote the Compose module in elm-monocle 😅), but there's one thing I'd like to add: a flipped version of the o operator (which we could name c?).

Why?

Consider this in the REAMDE's examples:

(o (o dictValues components_)
   (o each (o first (o just_ y_))))

At first glance, it's hard to tell what this is doing. Now let's straighten it out a bit with the forward operator:

y_
|> o just_ 
|> o first
|> o each
|> o components_
|> o dictValues

It's fine... but it goes in reverse kind of, starting from the "inwards" most optic to the "outwards" most. Feels a bit like holding a spyglass in reverse.

Now consider this:

dictValues
|> c components_
|> c each
|> c first
|> c just_ 
|> c y_

Here we see we start traversing dictValues, going inside the components_ field of those values, traversing each tuple taking the first value and searching for just_ something that has a y_ field.

Sure, we can already do that with:

o dictValues
<| o components_
<| o each
<| o first
<| o just_ y_

But it looks a bit less readable to me, with the last line having 2 optics to compose and all.

So, what do you think?

I'll send an MR if you like the idea :)

Hello and thanks for the great library!
This is more of a question than an issue. I am trying to update the value of a Dictionary at a specific key and I have been using atKey with no success. Here is the code

> Dict.fromList [("a", 5)] |> assign (atKey "a") 10
Dict.fromList [("a",5)]
    : Dict String number

Nothing changes in the returned dictionary. Same is true when using over

What am I doing wrong?

Curious if you've figured out how to integrate List.indexedMap and friends into this to build up the concept of Indexed Optics?