Swig, LLVM, LLILC

As I work to enhance Campy, a C# library for GPU programming I wrote, I’m trying to capitalize on some new code from the NET Foundation Projects. These include LLILC, a MS IL compiler based on LLVM. I want to be able to use some of the APIs in LLVM to perform SSA analysis rather than roll my own. But, that turns out to be easier said than done. This note describes some of the issues in building LLILC, LLVM, and SWIG.

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Getting Windows Subshell for Linux working

If you’ve been working with Cygwin or MinGW, you may want to step over to Windows Subsystem for Linux (WSL) to take advantage of building and running tools in that environment. While the goal of Cygwin and MinGW has been to provide a Linux command-line tool set to Windows, it’s too easy to run the wrong tool (e.g., forgetting to install a tool in one environment, and picking up the identically named tool in another). In fact, many tools install their own private copy of MinGW (Git for Windows, SourceTree, Vagrant, …), so you find yourself constantly manipulating the search path.

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Hackintosh for Development

Years ago, I bought a MacIntosh–the original 128K 68000 Motorola CPU  box. Like the Apple 2 before that, I upgraded it as best I could, and tried to develop programs for it. But, it was all not easy. And, it was exceedingly expensive–from the computer, to the upgrades, to the software, to the books detailing how to program the system. The decision by Apple to make the system so closed and so expensive made an impression that hasn’t changed over 30 years. I won’t buy an Apple product.

Unfortunately, if you are software developer, you have to use crap you really don’t want to use. The share of iPhones in the U.S. seems to be increasing, not decreasing, and I want to be able to write software for the iPhone. My dad, sisters, brother, and their families all own these exceedingly expensive cellphones. But, as Apple doesn’t give discounts for developers for their hardware, I decided to put together a hackintosh.

After a week or so, I finally found a hardware/software combination that seems to do the trick. My hackintosh is an Acer Aspire e5-574, with 6 GB memory, and an external 1 TB USB harddrive (Kingwin EZ-Dock 2535). It runs Sierra OS X, which I downloaded from a virtual machined hackintosh. It uses a USB keyboard and mouse as there are no drivers for the integrated keyboard and mouse. There are also no drivers for access to the internal SATA drive, which is why it runs with an external USB drive.

The hack wasn’t easy to set up. I’ve tried setting up El Capitan on two other Intel boxes and had no luck. I found the laptop hack after trying it out with the instructions on TonyMacX86.com. I’ll repeat the steps here.

Step 1: Download Sierra OS X.

  1. Start up an existing Mac.
  2. Download Sierra OS X.
  3. The files for OS X will be in /Applications.

Step 2: Create a bootable USB drive with UniBeast.

  1. Insert a USB thumb drive into the Mac. The USB drive should be 10 GB or more. If it doesn’t recognize the drive, try another.
  2. Open /Applications/Utilities/Disk Utility.
  3. Select the USB drive and erase it. The default should be OS X Extended (Journaled), and GUID Partition Map.
  4. Download Unibeast and run. You will need to sign up for a TonyMacX86.com account. I used UniBeast 7.0.1.
  5. In Unibeast, go through the preliminaries. Then select the destination USB drive, Sierra for the OS Installation, UEFI Boot mode. Then install.
  6. You should download MultiBeast and copy it to the USB drive. I used version 9.0.1.

Step 3: Set up BIOS settings on the laptop.

  1. Use “F2” repeatedly to get to the BIOS screen for the Acer.
  2. The only setting for the Acer laptop that is important is the Secure boot mode. Make sure it is turned off.

Step 4: Install OS X Sierra on the laptop.

  1. Insert the USB thumb drive on the laptop.
  2. Use “F12” to get the boot selector for the Acer laptop.
  3. Boot from the USB drive.
  4. In Clover, select the appropriate drive, then boot.
  5. After a long time, you should see an installation screen fro OS X.
  6. Insert the EZ-Dock drive.
  7. Format the EZ-Dock drive.
  8. Install Sierra on it.
  9. Reboot. Select the new drive. Sierra should come up.

Step 5: Post install

  1. Run MultiBeast on Sierra.
  2. Select Network and add in Atheros2200Ethernet 2.2.0, then install on the Sierra OS.
  3. Pull out the thumb drive, and reboot. It should now work.

Ken

Posted in Tip

C# Twisters–Round 2

More brain twisters. From http://stackoverflow.com/questions/241134/what-is-the-worst-gotcha-in-c-sharp-or-net, http://www.softwire.com/blog/2012/08/13/dont-be-too-lazy-linqs-lazy-evaluation-gotchas/, and others.

11.

static void CSharpPuzzle11()
{
    // Which implementation is faster?
    // Which implementation uses more memory?
    { // Implementation A.
        var before = DateTime.Now;
        int size = 100000;
        string a = string.Empty;
        for (int i = 0; i < size; ++i) a += i.ToString() + " ";
        var after = DateTime.Now;
        Console.WriteLine(a.SizeOf());
        Console.WriteLine(after - before);
    }
    { // Implementation B.
        var before = DateTime.Now;
        int size = 100000;
        StringBuilder a = new StringBuilder();
        for (int i = 0; i < size; ++i) a.Append(i.ToString() + " ");
        var after = DateTime.Now;
        Console.WriteLine(a.SizeOf());
        Console.WriteLine(after - before);
    }
}

12.

class Beer
{
    public bool IsAvailable;
    public bool IsNice;
    public string Name;
}

static void CSharpPuzzle12()
{
    Func<Beer, bool> BeerIsNice = (Beer b) =>
    {
        Console.WriteLine(b.Name);
        return b.IsNice;
    };

    List<Beer> availableBeers = new List<Beer>()
    {
        new Beer { Name = "Old Tom's", IsNice = false, IsAvailable = true },
        new Beer { Name = "Young Dan's", IsNice = true, IsAvailable = false },
        new Beer { Name = "Now Beer", IsNice = false, IsAvailable = true }
    };
    int count = availableBeers.Where(BeerIsNice).Count(); // What is the value of count?
    Console.WriteLine(availableBeers.Where(BeerIsNice).First().Name); // What is the output?
}


13.

private static IEnumerable<char> Keystrokes()
{
    while (true)
    {
        yield return Console.ReadKey(true).KeyChar;
    }
}

static void CSharpPuzzle13()
{
    // Why is keyboard read twice four times?
    System.Console.WriteLine("Enter 'beer'.");
    var firstFourKeystrokes = Keystrokes().Take(4);
    if (firstFourKeystrokes.SequenceEqual(new[] {'b', 'e', 'e', 'r'}))
    {
        System.Console.WriteLine("You entered 'beer'. Getting each char now...");
        firstFourKeystrokes.ToList().ForEach(Console.Write);
    }
}

14.

static void CSharpPuzzle14()
{
    // What's the correct way to create a new GUID?
    var which_one1 = new Guid().ToString();
    var which_one2 = Guid.NewGuid();
}

15.

static void CSharpPuzzle15()
{
    // What happens if you run this code?
    var t = new Program();
    var x = t.MyVar;
}

private int myVar;
public int MyVar
{
    get { return MyVar; }
}

16.

static void CSharpPuzzle16()
{
    // Why don't these work? How do we fix the problem?
    var a = Type.GetType("string");
    var b = Type.GetType("Program");
    var c = Type.GetType("System.Data.Entity.DbContext");
}

17.

static void CSharpPuzzle17()
{
    // Why doesn't this work? How do we fix it?
    for (int i = 0; i < 10; i++)
    {
        ThreadStart ts = delegate { Console.WriteLine(i); };
        new Thread(ts).Start();
    }
}

18.

static IEnumerable<char> CapitalLetters(string input)
{
    if (input == null)
    {
        throw new ArgumentNullException(input);
    }
    foreach (char c in input)
    {
        yield return char.ToUpper(c);
    }
}

static void CSharpPuzzle18()
{
    // Why doesn't this code throw an exception?
    try
    {
        var x = CapitalLetters(null);
        Console.WriteLine("An exception should have been thrown!");
    }
    catch (ArgumentNullException)
    {
        // Expected
    }
}

19.

static void CSharpPuzzle19()
{
    DateTime a = DateTime.Now;
    Thread.Sleep(2000);
    DateTime b = DateTime.Now;
    TimeSpan span = a - b;

    // Which is correct, the first or second line below?
    Console.WriteLine(span.Seconds);
    Console.WriteLine(span.TotalSeconds);
}

20.

static void CSharpPuzzle20()
{
    string my = "my ";
    var t1 = my + "string" == "my string"; //true

    var a = new ArrayList();
    a.Add(my + "string");
    a.Add("my string");

    // uses ==(object) instead of ==(string)
    var t2 = a[1] == "my string"; // True or False?
    var t3 = a[0] == "my string"; // True or False?

    var t4 = my + "string" == "my string"; // True or False?
}

21.

static void CSharpPuzzle21()
{
    // What does this output?
    string prefix1 = "C:\\MyFolder\\MySubFolder";
    string prefix2 = "C:\\MyFolder\\MySubFolder\\";
    string suffix1 = "log\\";
    string suffix2 = "\\log\\";

    Console.WriteLine(Path.Combine(prefix1, suffix1));
    Console.WriteLine(Path.Combine(prefix1, suffix2));
    Console.WriteLine(Path.Combine(prefix2, suffix1));
    Console.WriteLine(Path.Combine(prefix2, suffix2));
}

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Another Visual Studio Extension for Antlr4 Files: AntlrVSIX

There are several Visual Studio extensions for Antlr: Antlr4Code, ANTLR Language Support, Actipro SyntaxEditor for WPF, and Syntax Highlighting Pack. However, each has problems (works on Antlr3, has advertisements, does not offer a “go to definition” right-click context menu command, etc). So, over the last few days, I implemented a simple VS 2015/2017 extension for Antlr4 grammars. You can find the sources on Github (https://github.com/kaby76/AntlrVSIX). The extension implements “go to definition” and “find all references” for grammar symbols. There are some restrictions, but it’s a start, works well, and is very simple code. Enjoy!

(Edited Jan 14, 2017)

Posted in Tip

CSharp Puzzles for the Agile – Round 1

For those who have free time on their hands, and who would like to work through some brain twisters, here is a list of C# code snippets for your perusal. See https://www.toptal.com/c-sharp/top-10-mistakes-that-c-sharp-programmers-make for more details.

1.

//=============================================================================

private static void CSharpPuzzle1()
{
    Point point1 = new Point(20, 30);
    Point point2 = point1;
    point2.X = 50;
    Console.WriteLine(point1.X);       // What is the output?
    Console.WriteLine(point2.X);       // What is the output?
    Pen pen1 = new Pen(Color.Black);
    Pen pen2 = pen1;
    pen2.Color = Color.Blue;
    Console.WriteLine(pen1.Color);     // What is the output?
    Console.WriteLine(pen2.Color);     // What is the output?
    Console.WriteLine();
}

2.

//=============================================================================

static Pen pen1;
static Point point1;
public static void CSharpPuzzle2()
{
    Console.WriteLine(pen1 == null); // What is the output?
    Console.WriteLine(point1 == null); // What is the output?
    Console.WriteLine(point1 == default(Point));
    // Note: you can't declare an auto of a value type without an initializer!
    //Point p;
    //p.X = 1;
    Console.WriteLine();
}

3.

//=============================================================================

static void CSharpPuzzle3()
{
    string s = "strasse";

    // What is the output?
    Console.WriteLine(s == "straße");
    Console.WriteLine(s.Equals("straße"));
    Console.WriteLine(s.Equals("straße", StringComparison.Ordinal));
    Console.WriteLine(s.Equals("Straße", StringComparison.CurrentCulture));
    Console.WriteLine(s.Equals("straße", StringComparison.OrdinalIgnoreCase));
    Console.WriteLine(s.Equals("straße", StringComparison.CurrentCulture));
    Console.WriteLine(s.Equals("Straße", StringComparison.CurrentCultureIgnoreCase));
    Console.WriteLine(s == "strasse");
    Console.WriteLine(s.Equals("strasse"));
    Console.WriteLine();
}

4.

//=============================================================================

class Account
{
    [Key]
    public string ID { get; set; }
    public string Status { get; set; }
    public decimal Balance { get; set; }
}

static void CSharpPuzzle4()
{
    List<Account> myAccounts = new List<Account>()
    {
	    new Account() { Status = "active", Balance = 1 },
	    new Account() { Status = "inactive", Balance = 2 },
	    new Account() { Status = "active", Balance = 3 }
    };

    // What is the output?
    {
	    decimal total = 0;
	    foreach (Account account in myAccounts)
	    {
	        if (account.Status == "active")
	        {
		        total += account.Balance;
	        }
	    }
	    Console.WriteLine(total);
    }

    // What is the output?
    {
	    decimal total = myAccounts.Sum((account) => (account.Status == "active") ? account.Balance : 0);
	    Console.WriteLine(total);
    }
}

5.

//=============================================================================

class Accounts : DbContext
{
    public Accounts() : base("Accounts.DbConnection") {}

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
	    Database.SetInitializer<Accounts>(new SocialClubInitializer());
	    base.OnModelCreating(modelBuilder);
    }

    public DbSet<Account> _accounts { get; set; }
}

class SocialClubInitializer : DropCreateDatabaseAlways<Accounts>
{
    protected override void Seed(Accounts context)
    {
	    context._accounts.Add(new Account() { ID = "1", Status = "Active", Balance = 1 }); // Note capital "A"
	    context._accounts.Add(new Account() { ID = "2", Status = "Inactive", Balance = 2 });
	    context._accounts.Add(new Account() { ID = "3", Status = "Active", Balance = 3 }); // Note capital "A"
    }
}

static void CSharpPuzzle5()
{
    Accounts dbc = new Accounts();
    dbc.SaveChanges();
    var count = dbc._accounts.Count();
    {
	    decimal total = dbc._accounts.Sum(
	        (account) => (account.Status == "active") ? 
		    (decimal?) account.Balance :
		    0) ?? 0;
	    Console.WriteLine(total); // What is the output?
    }
}

6.

//=============================================================================

static void CSharpPuzzle6()
{
    int[] a = new int[] {1, 3, 5, 7, 9};
    int sum = a.Sum(); // Where is Sum defined?
    int len = a.Length; // Where is Length defined?
}

7.

//=============================================================================

static void CSharpPuzzle7()
{
    // Which implementation is faster?
    // Which implementation uses more memory?
    { // Implementation A.
	    var before = DateTime.Now;
	    int size = 100000000;
	    bool[] a = new bool[size];
	    for (int i = 1; i < size; ++i) a[i] = a[i - 1];
	    var after = DateTime.Now;
	    Console.WriteLine(a.SizeOf());
	    Console.WriteLine(after - before);
    }
    { // Implementation B.
	    var before = DateTime.Now;
	    int size = 100000000;
	    BitArray a = new BitArray(size);
	    for (int i = 1; i < size; ++i) a[i] = a[i - 1];
	    var after = DateTime.Now;
	    Console.WriteLine(a.SizeOf());
	    Console.WriteLine(after - before);
    }
}

8.

//=============================================================================

class SystemResource : IDisposable
{
    public void Dispose()
    {
        // The implementation of this method not described here.
        // ... For now, just report the call.
        Console.WriteLine(0);
    }
}

static void CSharpPuzzle8()
{
    // What is the output?
    using (SystemResource resource = new SystemResource())
    {
        Console.WriteLine(1);
    }
    Console.WriteLine(2);
    {
        SystemResource leak = new SystemResource();
        Console.WriteLine(3);
    }
    Console.WriteLine(4);
}

9.

//=============================================================================

class B { }
class D1 : B { }
class D2 : B { }

static void CSharpPuzzle9()
{
    try
    {
        B o = new D1();
        D2 c = (D2) o;
    }
    catch (Exception) { Console.WriteLine("Exception1"); }

    try
    {
        B o = new D1();
        D2 d = o as D2;
    }
    catch (Exception) { Console.WriteLine("Exception2"); }
}

10.

//=============================================================================

class CSharpPuzzle10
{
    // What does the compiler output for warnings and errors?
    int myId;
    int Id;
    CSharpPuzzle10(int id)
    {
        this.myId = Id;
    }
}
Posted in Tip

Getting Xamarin.Forms apps working with .NET Standard and Roslyn

Recently, I was trying to write a Xamarin.Forms app that uses Roslyn, Microsoft’s NET languages compiler framework. But, no matter what I did, it seemed as though it wasn’t possible. But, I tried a few things, and noticed that the Roslyn library could link with Android and iOS applications. That’s when I realized it might be possible.

That said, it depends on what you will be interested in of the Roslyn API. While one can parse and compile code from the .NET Standard/PCL library, Assembly.Load is essentially unavailable. Full functionality is available in Xamarin Android version 7. If you want to run compiled code, you need to use a bait/switch layer to accomplish that, in which case, you don’t need to make your PCL into a .NET Standard library, but it’s a good idea anyways.

Also, I’ve noticed VS 2015 is quite brittle in setting up an app to use .NET Standard. The following steps show that it can be done. Note: after each step, verify with a build and run.

  1. To set up a Xamarin Forms app to use the .NET Standard, open Visual Studio 2015 and create a blank cross-platform app that uses portable class libraries. You will see a portable class library and apps for each of the platforms.
  2. In the Project Explorer, Remove the Windows, Windows Phone apps, and leave the Android and iOS apps.
  3. Set the default project to the Android project. Build and run to make sure all is OK.
  4. Update the Xamarin.Forms in the three projects, to the latest version of Xamarin.Forms (2.3.3.175). Rebuild and run to make sure it works.
  5. In the Project Explorer, right-click on the References for the Xamarin Forms app portable class library, and “Manage NuGet Packages.” Remove the Xamarin.Forms library.
  6. Right-click on the portable class library, select Properties. Click on the Target .NET Standard hyperlink, then select NET Standard 1.5. Note, if you use .NET Standard 1.6, the References suddenly drops all DLL references, so don’t use that! In VS 2017, that appears to be fixed. Once VS has made the conversion, project.json will appear. After making the conversion, the default project has been reset. Set it back to the Android project.
  7. In the file project.json, change the ‘frameworks’ section with the following code, which allows the .NET Standard library to be compatible with certain PCL libraries.
 "frameworks": {
   "netstandard1.5": {
     "imports": [
       "portable-net45+wpa81+wp8+win8"
     ]
   }
 }
  1. Go back to the NuGet package management for the Xamarin Forms app PCL, add in Xamarin.Forms (the latest version).
  2. Rebuild and test. It should all work fine. If not, there is probably something wrong with your VS. Make sure it has the latest updates.

Roslyn works with .NET Standard, but adding it blindly causes a dependency/version issue. Roslyn requires Microsoft.Composition, but the version that it requires is old and incompatible with the .NET Standard (Package Microsoft.Composition 1.0.27 is not compatible with netstandard1.4 (.NETStandard,Version=v1.4). Package Microsoft.Composition 1.0.27 supports: portable-net45+win8+wp8+wpa81 (.NETPortable,Version=v0.0,Profile=Profile259)). Instead, add Microsoft.Composition first, then Microsoft.CodeAnalysis.

  1. In the Project Explorer, right-click on the References for the portable class library, and “Manage NuGet Packages.” Add in Microsoft.Composition (1.0.30), then Microsoft.CodeAnalysis (1.3.2). Make sure to add that to the Android project as well or you get “Severity Code Description Project File Line Source Suppression State
    Error Exception while loading assemblies: System.IO.FileNotFoundException: Could not load assembly ‘Microsoft.CodeAnalysis, Version=1.3.1.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35’. Perhaps it doesn’t exist in the Mono for Android profile….”

For a check, add source referencing some Roslyn classes, build and run.

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;

namespace App15
{
    public class Class1
    {
        public Class1()
        { }

        public static void YoDoit()
        {
            SyntaxTree tree = CSharpSyntaxTree.ParseText(@"
            public class MyClass
            {
                public int MyMethod()
                {
                    return 1+2;
                }
            }");
        }
    }
}

This code is in Github: https://github.com/kaby76/XamForms-Roslyn-Example

C# v7.0 pattern matching

Visual Studio “15” Preview 4 was recently released, so I decided to take it for a spin. In the upcoming C# 7.0, of the features being implemented, pattern matching is probably the most interesting. Consider how often we’ve designed code that uses a switch statement with complex cases, but then when we go to implement the design, a nested if-then-else statement must be coded instead because switch labels must be constant expressions. With pattern matching, this will finally change.

In theory, when the feature is fully implemented, we could write complex switch statements such as:

namespace ConsoleApplication4
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int j = 0; j < 20; ++j)
            {
                System.Console.WriteLine("j = " + j);
                switch (j)
                {
                    case var i when i % 2 == 0:
                        System.Console.WriteLine("Even");
                        break;
                    case var i when i > 10:
                        System.Console.WriteLine("OK, > 10");
                        break;
                    default:
                        System.Console.WriteLine("Anything else");
                        break;
                }
            }
        }
    }
}

Unfortunately, while this example compiles, it does not run properly yet, in Visual Studio “15” Preview 4.

Years ago, I used to write C code that would contain declaration expressions. This would simultaneously assign a value and test to see if the value was non-zero. You can do this in C++, e.g.,

// ConsoleApplication2.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

int foo() { return 1; }

int main()
{
    if (int a = foo()) printf("a = %d\n", a);

	// if ((int b = foo())) printf("\n"); does not compile.

	if (int x = 1 == 2)
		printf("x = %d\n", x); // OK, but x is 0, not 1 because of precedence rules.
	else
		printf("x = %d\n", x);
	
    // if ((int y = 1) == 2) return y; does not compile--does not like ()'s.

	// printf("x = %d\n", x); Note, x not available at this scope--outside if.

	// if (int c = 1 && int d == 2); Does not compile--only single variable can be declared.

    return 0;
}

In C#, we can use patterns to declare local variables within an expression, extending the declaration expression existing in C++:

namespace ConsoleApplication3
{
    class Program
    {
        static int foo() { return 1; }
        static void Main(string[] args)
        {
            if (foo() is var a) System.Console.WriteLine("a = {0}", a);

            // if ((int b = foo())) printf("\n"); does not compile.

            if (((1 == 2) is bool x) && ! x)
                System.Console.WriteLine("x = {0}", x);
            // else System.Console.WriteLine("x = {0}", x); // Does not compile "else" block--x is out of scope!

            if ((1 is int x) && x == 2)
                System.Console.WriteLine("x = {0}", x); // OK.

            // System.Console.WriteLine("x = {0}", x); // Note, x not available at this scope--outside if.

            if (1 is int c && 2 is int d)
                System.Console.WriteLine("c = {0}, d = {0}", c, d);
        }
    }
}

If the switch is rewritten as a nested if-then-else, the code works fine. Note, the scope of pattern matching variables is within the then clause, not the else clause of the if statement. I’m not sure why this would be the design, as in C/C++, the scope of declaration expression variables extend into the else clause. But perhaps it is to allow reuse of the same variable in a nested if-then-else.

namespace ConsoleApplication5
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int j = 0; j < 20; ++j)
            {
                System.Console.WriteLine("j = " + j);
                if ((j is var i) && i % 2 == 0)
                {
                    System.Console.WriteLine("Even");
                } else if ((j is var i) && i > 10)
                {
                    System.Console.WriteLine("OK, > 10");
                } else
                {
                    System.Console.WriteLine("Anything else");
                }
            }
        }
    }
}

Further Information

https://www.infoq.com/news/2016/04/CSharp-7

Essential .NET – Designing C# 7, Mark Michaelis, December 2015 https://msdn.microsoft.com/en-us/magazine/mt595758.aspx

Pattern Matching for C# https://github.com/dotnet/roslyn/blob/future/docs/features/patterns.md

https://github.com/dotnet/roslyn/issues/2136

https://github.com/dotnet/roslyn/issues/206

https://github.com/dotnet/roslyn/blob/future/docs/features/patterns.md

Advanced Pattern Matching Features Removed From C# 7 https://www.infoq.com/news/2016/05/csharp7-pattern-matching-removed

C# 7 Features Previewed https://www.infoq.com/news/2016/04/CSharp-7

Unification: pattern matching, but twice as nice! By: on May 31, 2011  http://www.lshift.net/blog/2011/05/31/unification-pattern-matching-but-twice-as-nice/

https://github.com/dotnet/roslyn/blob/master/docs/Language%20Feature%20Status.md

 

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Alternatives to Deeply-Nested Callback Functions in Javascript

A few days ago, I wrote a server in Node.js, the purpose of which is to email me when an API found in Nuget is updated. I thought the project would take a few hours, but as it turned out, it took several days. You may ask “How is this possible for such an easy problem?” Unfortunately, I spent a lot of time trying to figure out what API to use to read a text file, and how to use the API. It led me to an understanding of a fundamental problem with Javascript known as “callback hell” (1, 2).

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