new in-progress KEEP to improve the handling of `$` and `"` in (multiline) string literals -&gt; <ht...

# language-evolution

[Alejandro Serrano.Mena]

new in-progress KEEP to improve the handling of $ and " in (multiline) string literals -> https://github.com/Kotlin/KEEP/issues/375

[Klitos Kyriacou]

An interesting read. Thanks. I'm a bit confused by the following phrase on the linked page: "and the double dollar symbol prevents $0 and $@ to be considered interpolations". Do we really need the double dollar for that? Is there any way "$0" and "$@" can actually be interpolated?

[Alejandro Serrano.Mena]

mmm, maybe this was not clear... what I meant there is that by adding $$ at the beginning, the resulting string will contain the $0 as they were written

[Klitos Kyriacou]

But even with today's existing """ style, the $0 and $@ would still appear in the resulting string exactly as they were written, wouldn't they?

[Oliver.O]

Neither 0 nor @ are valid identifiers in Kotlin, so these would not be interpolated. The example in the KEEP looks incorrect.

[Alejandro Serrano.Mena]

thanks for the catch, let me fix this -> fixed to awk '!_[$NAME]++{print}' """$ARGS"""

[Oliver.O]

Maybe we could find a more idiomatic example: There is no notion of triple quotes in bash (what we're seeing is "" concatenated with "$ARGS" and another ""). ARGS is not a predefined variable. The awk expression is somewhat strange.

For awk, I'd consider something like this, which prints the last field (login shell) for the user "nobody":

awk -F : '/^nobody:/ { print($NF) }' /etc/passwd

For the "triple quote" we'd have to find something where it would actually make sense...

[Oliver.O]

Maybe this one:

println($$""""name = "Kotlin"; println("""Hello $name!""")"""")

[ephemient]

were Groovy's $/ /$ slashy strings considered? following similar rules, interpolation would use `$name`/`${expr}` same as other strings, and $$ would be a single literal $. IMO that would feel more natural than having to use increasing numbers of `$$`s

[Alejandro Serrano.Mena]

at the end you can ready a bit about other possibilities which were considered. In this case, we really wanted the ability to embed things like JSON schemas directly in a literal, without any further modification, this is partly why we went with longer interpolation syntax instead of longer escaping of $

[ephemient]

uninterpolated '''...''' would work for that goal too. although then I suppose it becomes a question of, do you want to introduce multiple new types of strings…