CL-INTERPOL modifies the reader so that you can have interpolation of
strings similar to Perl or Unix Shell scripts. It is a
text processing
convenience library. It also provides various ways to insert arbitrary characters into literal strings even if your editor/IDE doesn't support them.
Here's an example:
* (let ((a 42))
#?"foo: \xC4\N{Latin capital letter U with diaeresis}\nbar: ${a}")
"foo: ÄÜ
bar: 42"
It was written by Edi Weitz and now maintained by community at Github.
CL-INTERPOL can also be used for HTML templating: http://paste.lisp.org/display/146518