[spankalee]

I don't understand this rationale either:

> For the syntax of embedded expressions we considered using ${...}, but that would require a tag on string templates (either a prefix or a delimiter other than ") to avoid conflicts with legacy code.

Can't the template processor expression itself function as the tag? Is STR."..." already legal now?

[layer8]

They want

  String info = "My name is \{name}.";

to be a compile-time error because it is missing the template processor (e.g. the `STR.` prefix). Since existing code like

  String info = "My name is ${name}.";

is valid, they can’t use that syntax, or any other syntax that is currently allowed, as otherwise they would lose the ability to make it an error.

———

However, what they could have done instead is to use a syntax like

  String info = "My name is "(name)".";

i.e. place the interpolated expressions outside of string literals. Slightly longer, but maybe more readable and typable, and currently invalid syntax. (The parentheses would be mandatory.)

[ec109685]

Futzing around with quotes like that is worse to type and it’s nice having distinct characters for open and close.

[layer8]

It makes perfect sense to have the expressions outside of the string literals, exactly because they are expressions and not literal. Quotes express literalness, the opposite of evaluation.

This is simply replacing the existing

  "My name is " + name + "."

by

  "My name is " (name) "."

by eliminating the plusses, and adding parentheses to make expressions like

  "My name is " ("John") "."

unambiguous (a string template with one parameter that happens to be a string literal). The parentheses also indicate that this is a parameter, like for a function call, that is immediately evaluated. (The whole string template feature is really just syntactic sugar for a function call.)

That way you don’t have to “interrupt” string literals with an expression. Instead you end the string literal normally and then comes an expression.

A string template would be defined as any sequence of string literals and parenthesized expressions.

[ec109685]

I get that, but it’s hard to type accurately.