What's the canonical way to join strings in a list?

Question

I want to convert (\"USERID=XYZ\" \"USERPWD=123\") to \"USERID=XYZ&USERPWD=123\". I tried

(apply #\'concatenate \'string \'(\"         


        

Answer 1

Use FORMAT.

~{ and ~} denote iteration, ~A denotes aesthetic printing, and ~^ (aka Tilde Circumflex in the docs) denotes printing the , only when something follows it.

* (format nil "~{~A~^, ~}" '( 1 2 3 4 ))

"1, 2, 3, 4"
*