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

Like _stdbool, but with an int representation on the C side, reflecting one of many traditional (i.e., pre-C99) encodings of booleans.

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