How about representing a two-dimensional array in a point-free manner?

Exploring functional/tacit style programming, specifically implementing the snake game (example: )

The main issue at hand involves processing an array of strings like:

[
 ['2 '],
 ['10']
]

and obtaining a list of coordinates in numerical order of the 'value'. In this context, 0 represents the head of the snake, 2 the tail, and the whole structure represents the board.

With this in mind, the following function was created:

var findSnake = function(rendered_board) {
  return r.map(function(x) {
    return r.map(function (y) {
      return {
        x: x,
        y: y,
        val: rendered_board[x][y]
      };
    })(r.keys(r.split('', rendered_board[x])));
  })(r.keys(rendered_board));
};

As a result, the following output is obtained:


[ [ { x: '0', y: '0', val: '2' }, { x: '0', y: '1', val: ' ' } ],
  [ { x: '1', y: '0', val: '1' }, { x: '1', y: '1', val: '0' } ] ]

After sorting, this provides the desired list of coordinates. Despite its functionality, there are concerns regarding coding style.

Is it possible to rewrite findSnake using a point-free style? Are there more idiomatic solutions to this problem?

javascriptarraysfunctional-programmingramda.js

Answer №1

It's no surprise that transforming this into a concise, point-free solution would be overly complex. I attempted a simplified version of the problem, but even that was messy and didn't seem worth pursuing.

If we take a look at this initial function:

var fn = function(list) {
    return R.map(function(y) {
        return {
            y: y
        };
    }, list);
}

...which is clearly a subproblem of the larger issue, we can attempt to rewrite it like so:

var fn = R.pipe(R.converge(
    R.zip, 
    R.pipe(R.length, R.repeat('y')), 
    R.identity
), R.map(R.apply(R.createMapEntry)));

(For intermediate steps, refer to the REPL)

However, when using ES6 syntax, the approach seems quite counterproductive:

var fn = R.map(y => ({y});

This is why I opt for a point-free style when appropriate, but I don't force it into every situation.

Update

With version 0.18, Ramda changed `createMapEntry` to `objOf` and converted `converge` into a binary function. As a result, the previous code snippet no longer functions. The REPL link has also been updated. You can view the revised code in the REPL.

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