in Slim, you can take multiple lines to set attributes on a tag, if you use an attribute wrapper. For example, here's something I just tried:
script{
defer crossorigin="anonymous"
src="https://use.fontawesome.com/releases/v5.0.13/js/all.js"
integrity="sha384-xymdQtn1n3lH2wcu0qhcdaOpQwyoarkgLVxC/wZ5q7h9gHtxICrpcaSUfygqZGOe"
}
But in Slang (testing with 1.7.1), the above syntax produces an error on compilation, since it thinks there's an unterminated curly brace. This should probably work!