On this page:
yes
no?
no
maybe?

6.9 mischief/maybe: Optional Values🔗ℹ

 (require mischief/maybe) package: mischief-dev

struct

(struct yes (value)
    #:transparent)
  value : any/c
A struct that can be used for optional values that can include #false.

procedure

(no? x)  boolean?

  x : any/c
Equivalent to (false? x).

procedure

(no)  #false

Returns #false.

procedure

(maybe? x)  boolean?

  x : any/c
Equivalent to (or (yes? x) (no? x)).