In a double-quoted string, you will have to escape parens, double-quotes and single-quotes by prepending a single-quote.
You would have to escape double-quotes, though.
I like how Smalltalk handles this by allowing both single- and double-quotes as string delimiters:
"This is a string which includes two 'single quote' characters, which aren't escaped"
'This is a string which includes two "double quote" characters, which aren't escaped either'
This wouldn't work for Arc, though, if you also want to be able to use a _single_ single-quote for quoting symbols.
I've removed the sentence you quoted from my proposal.
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smalltalk "abc"= comment