CS141 Coursework 1 - Extension

This extension is a basic haskell webserver using Spock (was an absolute pain to setup)

What it does

The code initiates a web server running on port 8080. The server is purely and API only, and the front-end is in the respective folder of the main coursework zip. (You can also view the frontend live here)

The server accepts a get request to the root showing a default message, and accepts a POST request where the body is a JSON encoded grid. It returns either and empty list for not solvable or a list of grids that are either the solutions for the given grid or the rotations required to get to the solution.

JSON

The JSON encoding and decoding has been taken from Level.hs within the main coursework as the implementation for it was easy to use and follow. All credit goes to Michael Gale for them.

However I have modified the toJSON for a cell to include the truth option as the front end uses this to display which cells are enabled

Solving implementation

We have two POST routes available. The first is /grid-solve which accepts a JSON formatted grid and will return any grids that directly solve it on an empty array []

If grid-solve is empty then you should proceed to POST to /grid-steps which accepts the same JSON formatted grid and will also return a list of grids that result in the solution via rotations, or an empty array if it can't be solved.

Running

To run make sure to build using:

stack build --fast --pedantic

And then run using

stack exec cw1-ext-exe

In the project folder You can also run it via:

stack repl

then running

main

Then post a request to localhost:8080/grid-solve or localhost:8080/grid-steps where the post body is the JSON E.g.

{
  "rows": [
    {
      "cells": [
        { "action": "add", "operand": 2 },
        { "action": "add", "operand": 3 }
      ],
      "target": 3
    },
    {
      "cells": [
        { "action": "add", "operand": 5 },
        { "action": "add", "operand": 2 }
      ],
      "target": 4
    }
  ],
  "columns": [5, 2]
}

The expected output will be:

[
  {
    "rows": [
      {
        "cells": [
          { "act": { "action": "add", "operand": 5 }, "truth": false },
          { "act": { "action": "add", "operand": 3 }, "truth": false }
        ],
        "target": 3
      },
      {
        "cells": [
          { "act": { "action": "add", "operand": 2 }, "truth": false },
          { "act": { "action": "add", "operand": 2 }, "truth": false }
        ],
        "target": 4
      }
    ],
    "columns": [5, 2]
  },
  {
    "rows": [
      {
        "cells": [
          { "act": { "action": "add", "operand": 3 }, "truth": true },
          { "act": { "action": "add", "operand": 5 }, "truth": false }
        ],
        "target": 3
      },
      {
        "cells": [
          { "act": { "action": "add", "operand": 2 }, "truth": true },
          { "act": { "action": "add", "operand": 2 }, "truth": true }
        ],
        "target": 4
      }
    ],
    "columns": [5, 2]
  }
]

If you want a nicer view then I recommend using the web panel that visualises the returned grids here