%%VERSION%%
Sugar is a small monadic library that tries to simplify the use of error aware expressions with a monadic interface. Check out the the documentation online for more information.
- Unified interface to describe a result monad
- Module builders to customize the monadic interface to your project
- Works well on top of threading libraries like Lwt or Async
- Exception handling is supported to some degree with the strict interfaces
- Create an isolated module to describe your errors.
- Use one of Sugar's module builders to create a custom
Result
module for your project. This module will implement a clean DSL to help you create error aware computations. - Open and start using these modules.
The main idea of using this library is to help you use error aware expressions everywhere.
In the code bellow, we're using type hinting to make it clear the type result
is used to represent the current monad.
module Errors = struct
type t = Not_available | Unexpected of string
end
module Result = Sugar.Promise.Make (Errors) (Lwt)
open Errors
open Result
open Result.Infix
let program () : unit result =
return [1; 2; 3]
>>| List.length
>---------
( function
| Not_available -> return 0
| Unexpected s -> return 0
)
>>=
( fun len ->
Printf.printf "The len is %d\n" len;
return ()
)
let () =
Lwt_main.run ( unwrap (program ()) );;
The result monad will create a new type 'a result
that describes the result of any computation inside your project. If you use Lwt
, this type would take the form:
type 'a result = ('a, Errors.t) Result.result Lwt.t
The Result.result
type above comes from the result package. In recent versions of OCaml (>= 4.03), this type will be an alias for Pervasives.result
.