blog

12020-09-05

SEAN K.H. LIAO

monads

Weird concept thrown around by functional programming purists.

Basically, it is:

constructor

Your monad type is Wrap.

Your data type is Foo.

Your resulting type is Wrap{Foo} (or whatever notation you understand better).

converter

Also known as return or unit.

Your data type is Foo, and your data object is foo.

return foo results in wfoo of type Wrap{Foo}

combinator

Also known as bind or join.

You have wfoo of type Wrap{Foo}.

You have a function f that takes Foo and returns Wrap{Bar}

wfoo >>= f results in wbar of type Wrap{Bar}

Basically, invalid/failure/other is captured during both unwrapping and processing and preserved in the result. You deal with it later.