Monad

monad.types.monad - The Monad Class.

class monad.types.monad.Monad(value)

Bases: monad.types.applicative.Applicative

The Monad Class.

Implements bind operator >> and inverted bind operator << as syntactic sugar. It is equivalent to (>>=) and (=<<) in haskell, not to be confused with (>>) and (<<) in haskell.

As python treats assignments as statements, there is no way we can overload >>= as a chainable bind, be it directly overloaded through __irshift__, or derived by python itself through __rshift__.

The default implementations of bind, fmap and join are mutual recursive, subclasses should at least either overload bind, or fmap and join, or all of them for better performance.

bind(function)

The bind operation.

function is a function that maps from the underlying value to a monadic type, something like signature f :: a -> M a in haskell’s term.

The default implementation defines bind in terms of fmap and join.

fmap(function)

The fmap operation.

The default implementation defines fmap in terms of bind and unit.

join()

The join operation.

The default implementation defines join in terms of bind and identity function.

unit

The unit of monad.

alias of Monad

class monad.types.monad.Unit

Bases: object

Descriptor that always return the owner monad, used for unit.