Finding Text of Error

How would i find the text that would be displayed for any error when I catch it?
So,
(handler-case (error "HI") (error (er)
;;somehow return error string ("HI") that would've been displayed if hadn't been caught
))

By default, that is, when the first argument to ERROR is a string, which can be a format control string by the way, taking more arguments as arguments to format, a condition of type SIMPLE-ERROR which is a subtype of SIMPLE-CONDITION. You can retrieve the format control string and its arguments with SIMPLE-CONDITION-FORMAT-CONTROL and SIMPLE-CONDITION-FORMAT-ARGUMENTS, and then pass them to FORMAT with APPLY to construct the final string.

But you probably should create a custom condition class if you want to introspect it.

I think what he is asking is

(format t "~A" er)

cl-user> (handler-case (error "HI") (error (er)
(format t "~A~%" er)))
HI
nil

If you want a string (and not to print the text), you can use (format nil "~A" er) instead.

Ah, I forgot that while section 22.1.3 doesn't list conditions, their printing is specified explicitly. PRINC or PRINC-TO-STRING would be simpler than FORMAT for that case.

Exactly what i needed. Thx