Notes from a talk at Ember LA meetup on the topic of using a Maybe type and learning it via TDD of a bowling game.

bowling-with-monads.md

Links from talk, Bowling with Monads

• A practical example of TDDing a bowling game then refactoring to safely use undefined (& killing null too) with a "Maybe/Optional" type (a Monad).
• About the game, Bowling 101

The source code

• TDD bowling solution using a Maybe on branch safe-undefined, see README.

Maybe source code, See notes in comments

Tests for Maybe type which show how it works... how to operate on values in a container type. See the tests using .map, .chain, and .ap

Bowling game src code and tests using the Maybe type. See the roll function and frame function which use a Maybe; and notice that the scoring functions operate on the values contained in the Maybe.

There are some functional programing utilities methods here, for partial application and currying.

Learning a Maybe

• Article on Why Maybe
• Article with pictures on Functors, Applicatives, Monads

Libraries:

• Maybe-not
• True Myth

Functional programming:

• https://github.com/hemanth/functional-programming-jargon
• https://drboolean.gitbooks.io/mostly-adequate-guide/content/