iamarcel

Creating Neat .NET Core Command Line Apps

You can now read this on my (pretty) website! Check it out here.

Every reason to get more HackerPoints™ is a good one, so today we're going to write a neat command line app in .NET Core! The Common library has a really cool package Microsoft.Extensions.CommandlineUtils to help us parse command line arguments and structure our app, but sadly it's undocumented.

No more! In this guide, we'll explore the package and write a really neat

PollRobots

module tinybasic

open System

type Expression =
| Number of int
| Variable of string
| String of string
| Binary of Expression * string * Expression
| Unary of string * Expression

hijonathan

In your email:

<img src="https://path/to/mark-as-read?notificationId=1234&source=email" width="1" height="1" />

Bonus server-side:

When that endpoint is hit from an email, delay the response for 5-10s and listen for the connection being terminated early from the client. If they make it past 5-10s, then mark the notification as read. If not, then either they skimmed it or it was a fluke request.

ga2arch

module Main where

import Control.Monad.State
import Data.Char
import Data.List
import Data.Maybe
import qualified Data.Map as M

type Exprs = [Expr]
type Database = Exprs

andkerosine

$stack, $draws = [], {}

def method_missing *args
  return if args[0][/^to_/]
  $stack << args.map { |a| a or $stack.pop }
  $draws[$stack.pop(2)[0][0]] = args[1] if args[0] == :<
end

class Array
  def +@

crizCraig

import json
import os
import time
import requests
from PIL import Image
from StringIO import StringIO
from requests.exceptions import ConnectionError

def go(query, path):
  """Download full size images from Google image search.

parse

/* Compile with: g++ -Wall –Werror -o shell shell.c */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
 
#include <sys/types.h>
#include <sys/wait.h>

ofan

Lisp interpreter in 90 lines of C++

I've enjoyed reading Peter Norvig's recent articles on Lisp. He implements a Scheme interpreter in 90 lines of Python in the first, and develops it further in the second.

Just for fun I wondered if I could write one in C++. My goals would be

1. A Lisp interpreter that would complete Peter's Lis.py test cases correctly...
2. ...in no more than 90 lines of C++.

Although I've been thinking about this for a few weeks, as I write this I have not written a line of the code. I'm pretty sure I will achieve 1, and 2 will be... a piece of cake!

sanxiyn

#include <assert.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

enum type {
    NIL,

joshaven

  #############################################################################
  # Class: Vash (Ruby Volatile Hash)
  # Hash that returns values only for a short time.  This is useful as a cache
  # where I/O is involved.  The primary goal of this object is to reduce I/O 
  # access and due to the nature of I/O being slower then memory, you should also
  # see a gain in quicker response times.
  #
  # For example, if Person.first found the first person from the database & cache 
  # was an instance of Vash then the following would only contact the database for
  # the first iteration: