Module type Fail.S

The unary fail monad interface.

Implemented by:

type 'a error

a type of error

type 'a t

a monad type

val fail : _ error -> 'a t

fail err diverges the computation, possibly providing an extra information in a value of type _ error.

val catch : 'a t -> (_ error -> 'a t) -> 'a t

catch m f if m diverges with some bottom value err, the f err is a result of the whole computation, otherwise returns m.