the proposed new syntax

r{var1=@a; and var2=@foo}

is replaced by a tuple:

("var1=", a, "; and var2=", foo)

where @ denotes escaping symbols.

@ itself be escaped with \@.

optionally, expressions can be incorporated:

r{a2=@(a*2); and fooU=@(foo.toUpper)}

I've actually already implemented this feature via a mixin, and find it extremely useful, but removing the mixing via this proposal would make it even more palatable. It works using a simple grammar that searches for valid identifiers after a @, or finds nested expressions nested inside parenthesis (arbitrary nesting allowed).

Proper tooling will syntax highlight correctly the nested variables.

This feature is especially useful when there are a few variables involved, as alternatives are clunky

use cases:

A) simple string formatting (eg: formattedWrite)

----

q{first var=@a, second=@b, third=@c!}.foo

vs:

("first var=",a," second=",b," third=",c,"!").foo // `",,"` for a single `@`

("first var=%s, second=%s, third=%s!", a, b, c).foo => // error prone esp with many variables

or alternatives involving ~ :

("first var="~a.to!string~", second="~b.to!string~", third="~c.to!string~"!").foo //clunky

B) parsing (eg formattedRead)

same advantages as above