The _stdbool type represents the C99 bool type from <stdbool.h>. It translates #f to a 0 bool and any other value to a 1 bool.

Translates #f to a 0 int and any other value to a 1 int, reflecting one of many traditional (i.e., pre-C99) encodings of booleans. See also _stdbool.

Indicates a Racket #<void> return value, and it cannot be used to translate values to C. This type cannot be used for function inputs.