Nix uses string antiquotation, not string escaping. It's one of very few languages which has it. And yes, it is sane, very sane. The only sane solution to this problem.
Edolstra's thesis advisor was the first to create a scannerless GLR parser:
The first versions of Nix used a scannerless GLR parser, because it's the only way to prototype sophisticated features like antiquotation without going completely mad. Once the syntax was completely locked down it was rewritten with a separate scanner and LR(something) parser, but they're intricately entwined. The scannerful, non-GLR parser is faster but basically frozen and extremely difficult to modify. Fortunately Nix's syntax has been exceptionally stable for the last decade or more.
True string antiquotation is a feature that every language should have, but unfortunately with current technology it forces you to choose between a slow parser or a fast parser that's almost impossible to modify.
Some languages have "string interpolation" which is a weaker, more fragile form of antiquotation.
> Since ${ and '' have special meaning in indented strings, you need a way to quote them. $ can be escaped by prefixing it with '' (that is, two single quotes), i.e., ''$. '' can be escaped by prefixing it with ', i.e., '''. $ removes any special meaning from the following $. Linefeed, carriage-return and tab characters can be written as ''\n, ''\r, ''\t, and ''\ escapes any other character.
