guile-examples/macros/evaluation-time.scm

;; Using eval-when, one can tell Guile when an expression
;; should be evaluated. eval-when is followed by a list of
;; phase names. There are 4 phases one can specify: expand,
;; load, eval, compile. For more information see the
;; official manual at
;; https://www.gnu.org/software/guile/manual/html_node/Eval-When.html

;; Reminder:

;; #' = syntax -- what you write is just syntax -- pattern variables still inserted
;; #` = quasisyntax -- for when you need Scheme to calculate parts of the template
;; #, = unsyntax -- counterpart to quasisyntax -- evaluate expr inside an #` expr
;; #,@ = unsyntax-splicing -- evaluate and splice

(eval-when (expand load eval)
  (define-syntax give-thing
    (λ (something)
      (syntax-case something ()
        [(_ anything)
         (syntax
          (lambda (a . b) anything))]))))