Rust has a relational db library that connects to the db while you’re coding and uses the metadata to verify your code at compile-time.

Elm’s time traveling debugger.

Step backwards or forwards through the state of your program.

Perfect spot to come to get nerd sniped.

Watching this space

Ruby has something similar, keyword arguments - which allows you to name parameters:

def add_values(first:, second:)
  first + second
end

add_values(first: 5, second: 3)

Can be called in any order:

add_values(second: 3, first: 5)

Can be used with positional arguments:

def add_values(first, second:)
  first + second
end

add_values(1, second: 2)

And you can supply default values:

def add_values(first: 0, second:)
  first + second
end

I like how Rails generally has a lot of things built in that almost all apps/sites might use.

Recently I noticed Rails now also have a built in rate-limiter, super handy!

And something I have used in almost every Rails site is caching, which can really help make a site feel fast and responsive.

As an example:

Screenshot 2025-07-16 at 19.37.121200×451 30.4 KB

This is cached and the cache is busted when the updated_at field changes. It might not look like much but there are a lot of things that need to be calculated and pulled in - the category names and hover colours need to be worked out, the icon and colour in the top right needs to be worked out, the domain name is stripped from the full url, the tags need to be classified and displayed as portals or tags etc. That’s a lot of CPU per page without caching.

On top of that you can cache queries and set them to expire from as little as a minute to a day or more. I do this for even relatively simple queries as it can give you some protection against DDOS attacks.

    def latest_spotlight
      Rails.cache.fetch("latest_spotlight", expires_in: 1.hour) do
        Topic.where(category_id: Category.in_the_spotlight).includes(:image_upload).last
      end
    end

Without caching a Rails page load can show more than 20% CPU usage, with caching, as little as 1%.

Nothing. All cool things I have found in Elixir.