neongreen/artyom.me

artyom.me's Issues

[artyom.me] and [RSS] collide on mobile

Mention ALens etc. and ImpredicativeTypes in lens over tea

Use separate folders for posts, drafts, etc

Make font smaller

Embed post content in the feed

Move the recap of isomorphisms into lens-over-tea-4

Remove endnotes from lens-over-tea-2 (or is it 3?)

Replace “[RSS]” with an icon

Switch to make

make cv, make all, etc

Write a CV

Aeson tutorial: improve description of `.:?`

Currently it reads:

.:? is just like .:, but doesn't fail if the field wasn't found (it does fail if the field was found but has a different type, however).

That description actually matches the .:! operator, not .:?.

.:! doesn't fail if the field wasn't found.

.:? doesn't fail if the field wasn't found or if its value is Null.

See the docs for .:?.

This shouldn't usually come up, it can't hurt to be precise. I'm really enjoying the tutorial so far btw!

Possibly use jle's thing in lens over tea

02:08 <magbo> (<%~) l h y = l (\x -> (h x, h x)) y 
02:08 <magbo> Works on every lens.
02:08 <magbo> Returns (b, t) -- updated focused value and updated source
02:09 <puregreen> magbo: do you know how the Functor instance for (,) works?
02:09 <magbo> (,) is the outer functor, that was my intention when I was writing it
02:10 <magbo> puregreen: oh snap, it answers my question!
02:10 <jle`> it's Writer! :O
02:11 <jle`> magbo: `(\x -> tell (h x) >> return (h x))` would get you 
             the Writer translation of what you wrote
02:11 <puregreen> jle`: ooh, I like this one
02:12 <puregreen> gotta steal it for lens over tea
02:12 <jle`> it's technically wrong because it requires a Monoid instance i think
02:16 <jle`> puregreen: oh, you can get a working version of what i wrote
             with tell (h x) $> h x, because while it's equivalent to 
             tell (h x) *> return (h x), it doesn't require a Monoid constraint

Aeson tutorial: add an example of handling lowercase-but-camel fields, and underscored fields

Switch to HTTPS

https://letsencrypt.org/

People are linking to this repo instead of my site

@manpages is the first offender!

Slightly rewrite the Aeson tutorial

• remove the rant in the beginning
• mention <|> and sum types better

Isomorphism explanation, enum confusion

Hello,
First of all, thanks for the great series :)

I'm trying to understand the note about enum in lens over tea 4. Specifically, this part:

Now let's consider 2 cases – the first is when we use it to turn s into a, the second is when we use the iso to turn b into t. The definition we already have works well enough for the former case, but in the latter case s doesn't even exist:

enum f = \_ -> fromEnum <$> f ???

I don't understand what you mean by saying "turn the b into the t".

From what I understand,

enum :: Lens' Int a
enum :: Lens Int Int a a ~= Lens s t a b
b -> t :: a -> Int

why is this not a valid candidate?

enum_rev :: Lens' a Int
enum_rev f a = toEnum <$> f (fromEnum a)

Type signature of `iterated` is incorrect in lens over tea #3

You have

iterated :: Fold1 a a
iterated f g a = go a
  where go a = g a .> go (f a)

but I think it should be

iterated :: (a -> a) -> Fold1 a a
iterated f g a = go a
  where go a = g a .> go (f a)

The signatures in the open question below agree with this.

All the best,
Richard

lens-over-tea-1: outdated link. Hackage doesn't find Data.Bifunctor inside of bifunctors-5.5

The link in lens-over-tea-1.md

[`second`][] is a function from `Data.Bifunctor`

points to non-existing http://hackage.haskell.org/package/bifunctors-5.5/docs/Data-Bifunctor.html#v:second

Consider to replace it statically by
https://hackage.haskell.org/package/bifunctors-5/docs/Data-Bifunctor.html#v:second

Add lenses to the Aeson tutorial