You can search for identifiers within the package.
in-package search v0.2.0
module type C = sig ... end
val fft : (module C with type group = 'group and type scalar = 'scalar) -> domain:'scalar array -> points:'group list -> 'group list
val ifft : (module C with type group = 'group and type scalar = 'scalar) -> domain:'scalar array -> points:'group list -> 'group list