Installing Programming Language Toolchains

By David Chen @TheEgghead27

Plenty of programmers use Linux because it's super simple to set up tooling for pretty much any programming language you'd need!

For our meeting on December 1st, we looked at getting set up with a few common languages, and used them to try out this year's Advent of Code challenge.

Python

Python is such a ubiquitous programming language, most Linux distros come with it preinstalled, or even use it for their package manager!

Installing Python

To install Python on an Alpine image, run

apk add python3

Running Python

You can run python with the python3 command.

Usually, .py files are used for Python scripts, but you can name your script with any file name you want.

Making an executable script

If you want to be able to run your Python script as a program, perhaps in your terminal or for a cron job, you can do that with just a little bit of configuration.

At the very first line of your script, you need to add this comment:

#!/usr/bin/env python3

This tells the env program to run the appropriate copy of python3 (which matters when you have tons of different versions, each with different libraries, ask how I know...) against this script file.

You then need to tell Linux that this file is executable by running

chmod +x [script.py]

and that will be all! You can now simply run ./script.py instead of python3 script.py!

C(++)

C is one of the most significant systems programming languages, with the original Unix kernel's main advantage being written in C.

C is still used nowadays for the Linux kernel, along with tools like the GNU coreutil, cURL, DOOM, and many of your favorite programs.

C++ is (almost) a superset of C, which adds an object-oriented programming (OOP) paradigm, and a standard library full of premade datastructures. This is a favorite of competitve programmers for its C-like speed, while also offering compartmentalization that makes it useful for game engines like the Unreal Engine, and forks of the Cube engine (shameless plug).

Because C is such a crucial programming languages integrated with the Unix/POSIX system, effectively all Linux distributes provide a libc, for C standard functions like file handling. To provide C++ functions to build with, libstdc++, is often also provided. They also disribute the GNU Compiler Collection (GCC) which supports C via the gcc command and C++ via g++. The LLVM project's clang and clang++ are alternatives.

Installing GCC

We've already written a brief reference on installing essential (GCC) build tools on a couple common distros, but neglected to include Alpine.

To install the GCC and development libraries on Alpine, run

apk add build-base

Compiling C code

Let's start with a sample of C code you might have seen before, put this in a file called hi.c:

#include <stdio.h>

int main(void) {
        // part 3
        char secret[] = {0x42, 0x41, 0x54, 0x54, 0x45, 0x52, 0x59, 0x0};
        printf("%s\n", secret);
        return 0;
}

To compile C code, simply run

gcc hi.c

which will output the executable binary to ./a.out (not to be confused for the archaic A.OUT format!).

If you want to set a custom output filename, such as hi, you can say

gcc -o hi hi.c

Congratulations! You are now officially a "C programmer"!

Compiling C++ code

For C++ code, you should invoke g++ instead of gcc.

Rust

Rust is a modern systems language with advanced compile-time checking to ensure memory safety and other mitigations against common software snafus.

Its package manager is called cargo, and installing it will also bring along the compiler, rustc, and the rest of the toolchain.

To install it, run

apk add cargo

Starting a new Rust project

To set up a directory for a Rust project, run

cargo new [project_name]

This sets up a git repository with a few unadded files, such as Cargo.toml to manage this project's packages.

If you want to compile one file, gcc style, you can run

rustc [file.rs]

If you want to compile a whole project,

cargo build

takes care of it all, and will leave a binary nestled in the target folder.

Welcome to the land of zero cost abstractions and blazingly fast code, along with the lingering smell of crab.

Adventuring to Advent

This year's advent calendar started with a little problem about finding the first and last digits in a line.

Since this whole meeting was about installing and using programming languages, we went ahead and took shots at solving the problem.

Out of pure spite, Lenny decided to make a list-comprehension one-liner, which inspired some of the others to do so as well...

Below are some of our solutions:

with open("file.txt") as file: print(sum([int([z for z in line if z.isdigit()][0] + [z for z in line if z.isdigit()][-1]) for line in file.readlines()]))

By Lenny (153 chars)

f=open('a');print(sum((a:=[*filter(str.isdigit,i)])and int(a[0]+a[-1])for i in f.readlines()))

console.log(Deno.readTextFileSync('a').replace(/[^\d\n]/g,'').split('\n').map(i=>+(i[0]+i.slice(-1))).reduce((a,i)=>a+i))

By Nicolai (94 chars Python, 121 chars Deno)

And here's a solution that uses way too much threading because (and I quote) "someone had to do it":

import threading as np; result_list = []; lock = np.Lock(); [thread.start() and thread.join() for thread in [np.Thread(target=lambda line: (lock.acquire(), result_list.append(int(''.join(filter(str.isdigit, line))[0]+''.join(filter(str.isdigit, line))[-1])), lock.release()), args=(l,)) for l in open("file.txt", "r").readlines()]]; print(sum(result_list))

By Axel (356 chars)

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