$ cat s.scm
(format #t "~f\n" 2.5)

$ guile s.scm
;;; note: auto-compilation is enabled, set GUILE_AUTO_COMPILE=0
;;;       or pass the --no-auto-compile argument to disable.
;;; compiling /home/chris/s.scm
;;; compiled /home/chris/.cache/guile/ccache/3.0-LE-8-4.5/home/chris/s.scm.go
2.5
Backtrace:
In ice-9/boot-9.scm:
  1752:10  6 (with-exception-handler _ _ #:unwind? _ # _)
In unknown file:
           5 (apply-smob/0 #<thunk 7efd190d5540>)
In ice-9/boot-9.scm:
    724:2  4 (call-with-prompt ("prompt") #<procedure 7efd190e5760 …> …)
In ice-9/eval.scm:
    619:8  3 (_ #(#(#<directory (guile-user) 7efd190d9c80>)))
In ice-9/boot-9.scm:
   2835:4  2 (save-module-excursion #<procedure 7efd190c9150 at ice-…>)
  4380:12  1 (_)
In unknown file:
           0 (simple-format #t "~f\n" 2.5)

ERROR: In procedure simple-format:
In procedure simple-format: FORMAT: Unsupported format option ~f - use (ice-9 format) instead
guile (GNU Guile) 3.0.7
Packaged by Debian (3.0.7-deb+3.0.7-1)
Copyright (C) 2021 Free Software Foundation, Inc.

License LGPLv3+: GNU LGPL 3 or later <http://gnu.org/licenses/lgpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
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