Module BatResult

module BatResult: sig .. end
Monadic results of computations that can raise exceptions

type ('a, 'b) t = ('a, 'b) BatPervasives.result = 
| Ok of 'a
| Bad of 'b
The type of a result. A result is either Ok x carrying the normal return value x or is Bad e carrying some indication of an error. The value associated with a bad result is usually an exception (exn) that can be raised.
Since 1.0
val catch : ('a -> 'b) -> 'a -> ('b, exn) t
Execute a function and catch any exception as a result. This function encapsulates code that could throw an exception and returns that exception as a value.
Since 1.0
val catch2 : ('a -> 'b -> 'c) -> 'a -> 'b -> ('c, exn) t
As catch but two paramaters. This saves a closure construction
Since 2.0
val catch3 : ('a -> 'b -> 'c -> 'd) -> 'a -> 'b -> 'c -> ('d, exn) t
As catch but three paramaters. This saves a closure construction
Since 2.0
val get : ('a, exn) t -> 'a
get (Ok x) returns x, and get (Bad e) raises e. This function is, in a way, the opposite of the catch function
Since 2.0
val default : 'a -> ('a, 'b) t -> 'a
default d r evaluates to d if r is Bad else x when r is Ok x
Since 2.0
val map_default : 'b -> ('a -> 'b) -> ('a, 'c) t -> 'b
map_default d f r evaluates to d if r is Bad else f x when r is Ok x
Since 2.0
val is_ok : ('a, 'b) t -> bool
is_ok (Ok _) is true, otherwise false.
Since 2.0
val is_bad : ('a, 'b) t -> bool
is_bad (Bad _) is true, otherwise false
Since 2.0
val is_exn : exn -> ('a, exn) t -> bool
is_exn e1 r is true iff r is Bad e2 with e1=e2
val of_option : 'a option -> ('a, unit) t
Convert an option to a result
Since 1.0
val to_option : ('a, 'b) t -> 'a option
Convert a result to an option
Since 1.0

The Result Monad


This monad is very similar to the option monad, but instead of being None when an error occurs, the first error in the sequence is preserved as the return value.
module Monad: sig .. end

Infix

module Infix: sig .. end
This infix module provides the operator (>>=)
val print : ('b BatInnerIO.output -> 'a -> unit) ->
'b BatInnerIO.output -> ('a, exn) t -> unit
Print a result as Ok(x) or Bad(exn)