Result of watching to much #OPLSS videos

typed-css.md

CSS. Cascading Style Sheets. What are they?

Wikipedia says:

Cascading Style Sheets (CSS) is a style sheet language used for describing...

And one important observation: there are no abstraction mechanism in CSS. CSS expression evaluates to itself. Thus CSS is not very fascinating as a programming language.

There are sass, lesscss and others. They add some abbstractions mechanisms, notably variables and mixins (which are kind-of-functions). Yet I don't like them as languages, they are barely macro systems.

It would be nice to have pure (do you really need side-effects while generating CSS?) typed, well-designed CSS abstraction language.

Below is something I have in mind:

If you look at SASS' Variable Scope and Content Blocks -example:

$color: white;
@mixin colors($color: blue) {
  background-color: $color;
  @content;
  border-color: $color;
}
.colors {
  @include colors { color: $color; }
}

It could be:

color : Color
color = white

colors : Color -> Content -> Block
colors (color = blue) content = {
  background-color: color;
  content; -- slicing in, obvious by type. Or is type obvious by slicing?
  border-color: color;
}

.colors {
  colors _ { color: color; }; -- again sliced in, as result is Block
                              -- And first argument value is inferred (as there is a default value)
}

or @each directive example

@each $animal in puma, sea-slug, egret, salamander {
  .#{$animal}-icon {
    background-image: url('/images/#{$animal}.png');
  }
}

animals : [String]
animals = ["puma", "sea-slug", "egret", "salamander"]

-- all top level expressions, which aren't binding forms, are printed
for animals λ animal -> selector ("." ++ animal ++ "-icon") {
  background-image: url("/images/" ++ animal ++ ".png");
}

-- for : ∀ a b, [a] -> (a -> b) -> [b]
-- for = flip map

*So the question I try to ask is probably: *Is it possible to define language, which is syntactically superset of CSS, such that

• it is typed
• it is closer to Haskell than to BASIC

And if answer is yes, can someone implement one?