bs-promise-monad

Monadic syntax to work with promise in ReasonML

This project is a minimal syntax extension that help you to be more happy, and keep every promise in a way.

status

This module is simple and self-completed. It means that you can use it with confidence that it won't bring any breaking changes in a subsequent update.

installation

npm install bs-promise-monad --save

and add

bs-promise-monad into bsconfig.json.

Usage

simply

open PromiseMonad;

and enjoy life.

Example

let mySweetenPromise = return(2);

mySweetenPromise
>>= (value => {
    Js.log(value);
    return(value + 2);
  })
>>= (value => {
    Js.log(value);
    return(value + 3);
  })
>>| (err => {
    Js.log2("Failure!!", err);
    return(-2);
  });

/* With auto binding */
mySweetenPromise
>>- (value => {Js.log2("from first promise:",value); value+2})
>>- (value => {Js.log2("from second promise:", value); value+3})
>>- (err => {Js.log2("Handled error", err); err})

Reject the promise

exception Sorry;

error(Sorry)
>>= (x => Js.log("do it " ++ x) |> return)
>>| (err => return(Js.log2("I handled this", err)));

exception Sorry;
let breakPromise = return("I'm trying...");

breakPromise 
>>= ( x => Js.log("Program: " ++ x) |> return )
>>= ( y => error(Sorry) )   /* Reject here */
>>= ( z => Js.log("this is skipped")|>return)
>>| ( err => Js.log2("Handled error!!", err)|>return); /* Error handling here */

breakPromise 
>>- ( x => Js.log("Program: " ++ x))
>>- ( y => error(Sorry) )
>>- ( z => Js.log("this will be skipped"))
>>/ ( err => Js.log2("Handled error!! without explicit return", err));

let sequenceStart = return(7);

breakPromise >>* [
  (x => x+2),
  (x => x*3),
  (x => x+4)
]

/** With a final promise binding */
mySweetenPromise
>>- (value => {Js.log2("from first promise:",value); value+2})
>>- (value => {Js.log2("from second promise:", value); value+3})
>>. (value => Js.log2("This is my last promise", value))

Change

• v0.4.4 : Add >>. operator to ignore the final promise( to use in the last step )
• v0.4.3 : Remove unused dependency
• v0.4.1 : Add >>* operator
• v0.4.1 : Update bs-platfrom to 7.3.1
• v0.4.0 : Update bs-platform, bs-webapi. Add auto-catch(>>/) from @rolandpeelen . Many thanks!!
• v0.3.3 : fix module dependencies
• v0.3.0 : merge in auto-return(>>-) from @baldurh . Thanks!!
• v0.2.9 : fix type signature.
• v0.2.6 : update example on error handling
• v0.2.5 : add error handling (>>|)
• v0.2.0 : add Promise.reject by error