Monadic interface for The Elm Architecture.

A value of type IO m a is an effectful computation that can modify the model m, perform commands and contains values of type a.

Program using IO.

Port of Platform.program with IO.

Port of VirtualDom.program with IO (also works with HTML).

Port of Platform.programWithFlags with IO.

Port of VirtualDom.programWithFlags with IO (also works with HTML).

Returns an IO whose only effect is containing the value given to pure.

Lift a Cmd as an IO

Lift a CmdM as an IO

An IO doing nothing (an containing no values!)

An IO that returns the current model

An IO that sets the model

A IO that modify the model

Map a function over an IO. Laws

• map (f >> g) = (map f) >> (map g)
• map identity = identity

Chains IOs.

If you have an IO model a and a function which given a a can give you an IO model b depending on the value of type a given to the function. Then bind gives you an IO model b that will run the first IO and then apply the function.

Laws

• bind pure = identity
• bind (f >> pure) = map f
• (bind f) >> (bind g) = bind (a -> bind g (f a))

Flatten an IO containing an IO into a simple IO. Laws

• join (pure m) = m

Transform an IO containing functions into functions on IO It enable to easily lift functions to IO.

Laws

• ap (pure identity) = identity
• ap (pure (f >> g)) = ap (pure f) >> ap (pure g)

You can think of traverse like a map but with effects. It maps a function performing IO effects over a list.

Transform a list of IO into an IO of list.

Congruence by a Lens on an IO.

It would be silly to force users to redefine every IO for each application model. Lenses enable to lift an IO action on a model a to the same IO but action on a model b.

You can then define your IO on the minimal model and lift them to you real application's model when needed.

Congruence by a Select on an IO. Just like lenses but with Select

Transform a program using IO into a normal program.

Transform a program using IO into a normal program.

Combine a list of IO. Its use is strongly discouraged! Use mapM instead!

Combine two IO. Its use is strongly discouraged! Use mapM instead!