action has wrong type in ReasonReact reducer - reason

Question

I'm trying to create a simple todo app, this is an input component and I need a reducer to update the state of the input. This code is throwing the error - This pattern matches values of type action but a pattern was expected which matches values of type unit => string
For some reason it expects action to be unit => string and I have no idea why. Can anyone help?
type state = string;
type action =
| InputChange(string);
let component = ReasonReact.reducerComponent("Input");
let make = (~onSubmit, _children) => {
...component,
initialState: () => "",
reducer: action =>
switch (action) {
| InputChange(text) => ReasonReact.Update(text)
},
render: ({state: todo, send}) =>
<input
className="input"
value=todo
type_="text"
placeholder="What do you want todo"
onChange={e => send(ReactEvent.Form.target(e)##value)}
onKeyDown={
e =>
if (ReactEvent.Keyboard.key(e) == "Enter") {
onSubmit(todo);
send(() => "");
}
}
/>,
};

Answer 1

The type of action is inferred by the use of send in render, where you pass it () => "", a function of type unit => string. It should be send(InputChange("")).
You're also missing the state argument on reducer. It should be reducer: (action, state) => ..., or reducer: (action, _state) => ... to avoid the unused warning, since you're not using it.