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Iterating over (x,y) positions of a grid using functional programming methods

By : Israr Zaib
Date : October 14 2020, 02:22 PM
wish helps you As @hellow pointed out in the comments, there's an iproduct macro in the itertools crate that does what I want. Using it, my code can be rewritten like this:
code :
use itertools::iproduct;
let coords = iproduct!(0..WIDTH - 1, 0..HEIGHT - 1);

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Transformation of a list of positions to a 2D array of positions using functional programming (F#)

By : Casey Wright
Date : March 29 2020, 07:55 AM
seems to work fine It depends on the definition of "functional". I would say that a "functional" function means that it always returns the same result for the same parameters and that it doesn't modify any global state (or the value of parameters if they are mutable). I think this is a sensible definition for F#, but it also means that there is nothing "dis-functional" with using mutation locally.
In my point of view, the following function is "functional", because it creates and returns a new matrix instead of modifying an existing one, but of course, the implementation of the function uses mutation.
code :
let performStep m =
  let res = Matrix.Generic.create 6 6 [] 
  let pos = [(1.3,4.3); (5.6,5.4); (1.5,4.8)]   
  for pz, py in pos do
    let z, y = int pz, int py 
    res.[z,y] <- (pz,py) :: m.[z,y] 
let sp = pos |> List.map (fun (pz, py) -> int pz, int py, (pz, py)) 
let elementsToAdd = Matrix.Generic.initSparse 6 6 sp
let res = Matrix.init 6 6 (fun i j -> 
  match elementsToAdd.[i, j], m.[i, j] with
  | Some(n), res -> n::res
  | _, res -> res )

Is there an option to display grid, for programming positions of visible material on screen?

By : user3537052
Date : March 29 2020, 07:55 AM
should help you out How about drawing a grid? Simply add operations for drawing it to the page content during development.
E.g. you can do it like in this sample based on the PDF Clown sample HelloWorldSample.java:
code :
// 1. Instantiate a new PDF file!
 * NOTE: a File object is the low-level (syntactic) representation of a
 * PDF file.
org.pdfclown.files.File file = new org.pdfclown.files.File();

// 2. Get its corresponding document!
 * NOTE: a Document object is the high-level (semantic) representation
 * of a PDF file.
Document document = file.getDocument();

// 3. Insert the contents into the document!

// 3.5 Add a grid to the content

// 4. Serialize the PDF file!
file.save(new File(RESULT_FOLDER, "helloWorld-grid.pdf"), SerializationModeEnum.Standard);

void addGrid(Document document)
    for (Page page: document.getPages())
        Dimension2D pageSize = page.getSize();
        PrimitiveComposer composer = new PrimitiveComposer(page);

        composer.setStrokeColor(new DeviceRGBColor(1, 0, 0));
        for (int x = 0; x < pageSize.getWidth(); x+=20)
            composer.startPath(new Point2D.Float(x, 0));
            composer.drawLine(new Point2D.Double(x, pageSize.getHeight()));

        for (int y = 0; y < pageSize.getHeight(); y+=20)
            composer.startPath(new Point2D.Float(0, y));
            composer.drawLine(new Point2D.Double(pageSize.getWidth(), y));



Iterating over Linked List using Functional programming paradigm

By : user3672094
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further Not sure how underscore would factor in. Doesn't really seem necessary to get functional style code.
code :
function doCell(c) {
    if (!c || your_condition_is_met)
        return c;
    return doCell(c.next);

var result = doCell(cell);
function nextWhile(v, callback) {
    if (!v || callback(v))
        return v;
    return nextWhile(v.next, callback);
var result = nextWhile(cell, function(cell) {
    return your_condition_is_met;
function cell_is_something(cell) {
    return your_condition_is_met;
var result = nextWhile(cell, cell_is_something);

Swift Functional Programming: iterating tuples

By : Qi Wei
Date : March 29 2020, 07:55 AM
Does that help This is the loop I have using for:
code :
let titles = json["codes"].map { $0.1["title"].string! }
let urls = json["codes"].map { $0.1["url"].string! }

Functional Programming: is foldLeft is the parent method of all functional methods such as foldRight, map, filter

By : Andres Campos
Date : March 29 2020, 07:55 AM
hop of those help? In general, no, foldLeft is not the "father" of all other methods, because there are many collections other than List. For example, you can not implement Stream.map via Stream.foldLeft because foldLeft does a full traversal but map should not traverse the stream because of its laziness (it can be potentially infinite).
As to the List you are mostly right. However, some methods will be extremely inefficient if implemented via foldLeft. Consider list.drop(1). It should just return the tail of the list, but foldLeft would do a full traversal.
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