I use sth like solid’s classList

<div class={class_list(%{
    "these classes are always included" => true,
    "these only when foo is 0" => @foo == 0,
    "only when bar aint baz" => @bar != "baz"
  })
}>

def class_list(map) do
  map
  |> Enum.filter(fn {_, include?} -> include? end)
  |> Enum.map(fn {class, _} -> class end)
  |> Enum.join(" ")
end

thats OK, but it would be nice if we could do

<div class_list={%{
    "these classes are always included" => true,
    "these only when foo is 0" => @foo == 0,
    "only when bar aint baz" => @bar != "baz"
  }}
>

What are some other approaches?