F# Pathfinding

I've recently started to have a play around with F# and for my first non-trivial application I'm thinking of implementing a path finding algorithm as seen in games. Seeing as this is a learning exercise I'm going to try and be as "functional" as possible (trying to stay as "pure" as I can with immutable data).

First things first:
We'll need a world to 'path find' our way around. Lets start off with defining some simple utility functions. Below is my Tools module that contains functions to:

• Square ints to a float 
• Remove items from lists 
• Load ints from a file (2D arrays of numbers will serve as our tile maps, collision maps, monster & item locations, etc)

The map:
Ok we still need to describe the world we want to navigate: In our world a 0 represents an open space and a 1 represents an area we can not enter. For example a 4 unit long corridor, running left to right, would look like this:

* Wall 1 1 1 1
* Void 0 0 0 0
* Wall 1 1 1 1

Here is my level module that describes:

• Map point: an x,y location in our 2D space, plus the value of the tile at that location and a function to calculate distance from another map point
• Map: a list of map points and a function to get the neighboring tiles of any given tile

Pathfinding: Now comes the fun part. This contains the PathingNode type (that basically wraps a map location with information that the A* path-finding algorithm needs), some utility functions and the path-finding function itself.

Level 1: Now let's create a file to represent our world. Open up a text editor and and create a delimited 2D array of 0's and 1's with a definite path between 2 points. like so:

* 0; 0; 0; 0; 0;
* 0; 0; 0; 1; 0;
* 0; 0; 0; 1; 0;
* 0; 1; 1; 1; 1;
* 0; 0; 0; 0; 0;
* 1; 1; 1; 1; 0;
* 0; 0; 0; 0; 0;
* 1; 0; 1; 1; 1;
* 0; 0; 0; 0; 0;

(I've highlighted my start tile green and end tile red for reference)
...Save this text file some where on your hard drive for later.
The Results:
The code bellow shows the pathfinding in action: