Comment by JonChesterfield

Are you sure you want that? It's possible to use whitespace and conventions to denote s-expr. For example, have each line implicitly start with a ( and use \n for ). More complicated schemes involving counting indentation also available. Anything you like that parses to a tree really.

The price will tend to be that working out what the code parses to gets much more difficult for the programmer. The parser won't care. Guessing what the programmer might have meant for error messages gets harder. Copying code around in a file will tend to change the meaning.

Worth noting that dear python, whitespace enthusiast, still has spurious : scattered around to give slightly better behaviour on syntactically invalid input, and they managed to compromise the semantics of lambda to keep the whitespace magic working.

An alternative you might like is colouring parens light grey (or dark, whatever mostly matches the editor background) and have the editor insert them for you.