The backslash string wrapping feature is a fairly obscure part of
haskell syntax, and some tools don't handle it properly (e.g. the
built in 'lex' function won't lex such strings properly). It's also
not as useful as e.g. python's triple quotes, because you have to
suffix and prefix every line with a backslash. As long as you are
have to add suffixes and prefixes (i.e. straight cut and paste no
longer works), you might as well write it out with (++). In other
words, as long as you're applying ('\\':) . (++"\\") you might as well
apply ("++ \""++) . (++"\""). And it seems to me that "string
literal" ++ "another string" is an easy thing for a compiler to
optimize, ghc-core says ghc unsurprisingly has no trouble with it.
So it's probably not helpful for performance. IMO it's not very
useful for it's intended purpose (embedding multiline strings) because
of the \s everywhere. It doesn't seem very widely used, and it adds a
little bit of a hassle to parsing. And 'lex' doesn't support it.
Any interest in getting rid of it?
I would actually be in favor of triple quotes (yeah, I know it can be
done with quasi-quotes, but still...), but that's a different issue.
Also, it's hardly a big deal, but do we really need \a, \b, \f, and
\v? The one time I used one (it was \v) it was a typo and I would
have preferred the parse error, instead I got weird output that I
didn't notice for a long time. If I really want to, say, ring the
terminal bell or do a vertical tab or perhaps send a telegraph, I
would be using some library that handles terminal type stuff in a
higher level way. Similarly, the \EM, \DC1, etc. codes are probably
not pulling their weight. The '70s were 40 years ago! And there's
that weird \& thing. Surely cursor control library authors have
better ways to construct their magic codes.
