+(define toplevel? (make-fluid))
+
+(define compile-time-too? (make-fluid))
+
+(defspecial eval-when (loc args)
+ (pmatch args
+ ((,situations . ,forms)
+ (let ((compile? (memq ':compile-toplevel situations))
+ (load? (memq ':load-toplevel situations))
+ (execute? (memq ':execute situations)))
+ (cond
+ ((not (fluid-ref toplevel?))
+ (if execute?
+ (compile-expr `(progn ,@forms))
+ (make-const loc #nil)))
+ (load?
+ (with-fluids ((compile-time-too?
+ (cond (compile? #t)
+ (execute? (fluid-ref compile-time-too?))
+ (else #f))))
+ (when (fluid-ref compile-time-too?)
+ (eval-elisp `(progn ,@forms)))
+ (compile-expr-1 `(progn ,@forms))))
+ ((or compile? (and execute? (fluid-ref compile-time-too?)))
+ (eval-elisp `(progn ,@forms))
+ (make-const loc #nil))
+ (else
+ (make-const loc #nil)))))))
+