Ho do I print a formatted output in Common Lisp?
In Racket I do it with display, like so:
(display "\33[3min italics\33[m\n")
I've tried with (format t "~ain italics~a" "\33[3m" "\33[m") but it does not work. Neither does this: (format t "~cin italics~c" #\33[3m #\33[m).
The main issue here is how to get the proper sequence of characters. \33 is octal for ascii char 27 or #\Esc in Common Lisp.
(format t "~C[3min italics~C[m~%" #\Esc #\Esc)
would do what you want.
But you could do better than that. There is a library called cl-interpol which demonstrates flexibility of Common Lisp by modifying the reader so you could use the already familiar syntax. For example:
* (ql:quickload 'cl-interpol)
To load "cl-interpol":
Load 1 ASDF system:
cl-interpol
; Loading "cl-interpol"
...
(CL-INTERPOL)
* (named-readtables:in-readtable :interpol-syntax)
#<NAMED-READTABLE :INTERPOL-SYNTAX {1002E6D6B3}>
* (format t #?"\33[3min italics\33[m\n")
in italics
NIL