Monads 1

An introduction to monads including the definition and a look at the monoid monad.

• Category

  Howto & Style

[TheCatsters]

Thanks crowlogic and tehrba. I think you each have a point...I've heard that some non-native English speakers were having some trouble so I'll experiment with speaking a little more slowly. Just a little...

[entropyfails]

A note for Haskell programmers....

η is the mentioned Eta and is the Monadic equivalent of the Haskell "return" function.

μ is the mentioned Mu and is the Monadic equivalent of the "join" operator.

"map" comes for free in Category Theory. So the Haskell bind operator of ">>=" over a list type is x >>= f = join (map f x)

These videos show why the Monad typeclasses must obey the three laws.

1. return a >>= f = f a

2. m >>= return = m

3. (m >>= f) >>= g = m >>= (\x -> f x >>= g)

[chocojian]

YouTube lectures on category theory! Awesome! I hope more mathematicians follow your example in the future. This is a great idea.

[TheCatsters]

Thanks!

[targetrich]

phew. Get out, have a drink. read some greek philosophy!

[skip84]

I feel dumb...

[balodja]

Oh, on-line school :) That's awesome.