Add flatMap and leftMap to Maybe types

[joelnet]

Add the flatMap and leftMap functions to Just and Nothing.

• Nothing.flatMap will work just like map and return Nothing.
• Just.flatMap will be similar to map, but it will not box the value in a Just.
• Just.leftMap will not execute the function and return the Just.
• Nothing.leftMap will execute the function and return the value.

Expected behavior

const upper = s => typeof s === 'string' ? Just (s.toUpperCase ()) : Nothing

Just ('abc').flatMap (upper) //=> Just('ABC')
Just (123).flatMap (upper) //=> Nothing
Nothing.flatMap (upper) //=> Nothing

Just ('abc').leftMap (upper) //=> Just('abc')
Nothing.leftMap (() => Just ('ABC')) //=> Just('ABC')
Nothing.leftMap (() => Nothing) //=> Nothing

[johnpaulada]

Hi! Can I try working on this?

[joelnet]

How is your progress going? Do you need any help?

I just created a Discord chat channel. Hit me up there if you have questions. https://discord.gg/Gg7ptD5

[thanhcng]

Hi, can I work on this issue instead?

[johnpaulada]

Sorry I was having internet difficulties. Third world country 😞

[joelnet]

lol no worries. I am having internet difficulties right now too. Guess it's contagious :)

Still plenty of issues left to tackle :)

Cheers!