# React

Implement a basic reactive system.

Reactive programming is a programming paradigm that focuses on how values
are computed in terms of each other to allow a change to one value to
automatically propagate to other values, like in a spreadsheet.

Implement a basic reactive system with cells with settable values ("input"
cells) and cells with values computed in terms of other cells ("compute"
cells). Implement updates so that when an input value is changed, values
propagate to reach a new stable system state.

In addition, compute cells should allow for registering change notification
callbacks.  Call a cell’s callbacks when the cell’s value in a new stable
state has changed from the previous stable state.


## Getting Started
For installation and learning resources, refer to the
[exercism help page](http://exercism.io/languages/ocaml).

## Installation
To work on the exercises, you will need `Opam` and `Core`. Consult [opam](https://opam.ocaml.org) website for instructions on how to install `opam` for your OS. Once `opam` is installed open a terminal window and run the following command to install core:

```bash
opam install core
```

To run the tests you will need `OUnit`. Install it using `opam`:

```bash
opam install ounit
```

## Running Tests
A Makefile is provided with a default target to compile your solution and run the tests. At the command line, type:

```bash
make
```

## Interactive Shell
`utop` is a command line program which allows you to run Ocaml code interactively. The easiest way to install it is via opam:
```bash
opam install utop
```
Consult [utop](https://github.com/diml/utop/blob/master/README.md) for more detail.

## Feedback, Issues, Pull Requests
The [exercism/ocaml](https://github.com/exercism/ocaml) repository on
GitHub is the home for all of the Ocaml exercises.

If you have feedback about an exercise, or want to help implementing a new
one, head over there and create an issue.  We'll do our best to help you!


## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.