Add hello-world examples to development shells

README.org

@@ -247,6 +247,16 @@ in mkShell {
 #+ATTR_LATEX: :width 400px
 [[./docs/images/golang.png]]
 
+#+BEGIN_SRC go
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello, world!")
+}
+#+END_SRC
+
 [[https://golang.org][Go]] is an open-source programming language that makes it easy to build simple, reliable, and efficient software. It's statically typed and compiled programming language. It's syntactically similar to C, but with memory safety, garbage collection, structural typing, and CSP-style concurrency.
 
 Import this shell with ~nix develop $DOTFILES#go~
@@ -278,7 +288,14 @@ mkShell {
 #+ATTR_LATEX: :width 400px
 [[./docs/images/rust.png]]
 
-[[https://rust-lang.org/][Rust]] is a multi-paradigm programming language designed for performance and safety, especially safe concurrency. It is syntactically similar to C++, but can garantee memory safety by using a borrow checker to validate references. Rust achieves memory safety /without/ garbage collection, and reference counting is optional.
+#+BEGIN_SRC rust
+fn main() {
+    println!("Hello, world!");
+}
+#+END_SRC
+
+[[https://rust-lang.org/][Rust]] is a multi-paradigm programming language designed for performance and safety, especially safe concurrency. It is syntactically similar to C++, but can garantee memory safety by using a borrow checker to validate references. Rust achieves memory safety /without/ garbage collection, and reference
+counting is optional.
 
 Import this shell with ~nix develop $DOTFILES#rust~
 
@@ -306,6 +323,15 @@ mkShell {
 #+ATTR_LATEX: :width 400px
 [[./docs/images/node.png]]
 
+#+BEGIN_SRC js
+var http = require('http');
+
+http.createServer((req, res) => {
+    res.WriteHead(200, { 'Content-Type': 'text/html' });
+    res.end('Hello, world!');
+});
+#+END_SRC
+
 [[https://nodejs.org][NodeJS]] is an open-source, cross-platform, back-end JavaScript runtime environment that runs on the V8 engine, and executes JavaScript code outside of a web browser. NodeJS lets developers user JavaScript to write command line tools, and for server-side scripting to produce dynamic web page content.
 
 Import this shell with ~nix develop $DOTFILES#node~
@@ -336,6 +362,14 @@ mkShell {
 #+ATTR_LATEX: :width 300px
 [[./docs/images/java.png]]
 
+#+BEGIN_SRC java
+class Program {
+    public static void main(String[] args) {
+	    System.out.println("Hello, world!");
+	}
+}
+#+END_SRC
+
 [[https://openjdk.java.net][OpenJDK]] is a free and open-source implementation of the [[https://en.wikipedia.org/wiki/Java_(software_platform)][Java]] Platform, Standard Edition. It is the result of an effort Sun Microsystems began in 2006. The implementation is licensed under the GNU General Public License Version 2 with a linking exception.
 
 Import this shell with ~nix develop $DOTFILES#java~
@@ -362,6 +396,15 @@ mkShell {
 #+ATTR_LATEX: :width 300px
 [[./docs/images/grpc.png]]
 
+#+BEGIN_SRC protobuf
+service Greeter {
+  rpc SayHello (HelloRequest) returns (HelloResponse);
+}
+
+message HelloRequest { string name = 1; }
+message HelloResponse { string response = 1; }
+#+END_SRC
+
 [[https://grpc.io][gRPC]] is a modern open-source, high-performance Remote Procedure Call (RPC) framework that can run in any environment. It can efficiently connect services in and across data centres with pluggable support for load balancing, tracing, health checking, and authentication.
 
 Import this shell with ~nix develop $DOTFILES#grpc~
@@ -390,8 +433,17 @@ mkShell {
 #+ATTR_LATEX: :width 300px
 [[./docs/images/cc.png]]
 
-[[https://iso.org/standard/74528.html][C]] is a general-purpose, procedural computer programming language support structured programming, lexical variable scope, and recursion. It has a static type system, and by design provides constructs that map efficiently to typical machine instructions. [[https://en.wikipedia.org/wiki/C++/][C++]] is a general-purpose programming language created as an extension of the C programming language.
+#+BEGIN_SRC c++
+#include <iostream>
 
+int main() {
+  std::cout << "Hello, world!\n";
+  return 0;
+}
+#+END_SRC
+
+
+[[https://iso.org/standard/74528.html][C]] is a general-purpose, procedural computer programming language support structured programming, lexical variable scope, and recursion. It has a static type system, and by design provides constructs that map efficiently to typical machine instructions. [[https://en.wikipedia.org/wiki/C++/][C++]] is a general-purpose programming language created as an extension of the C programming language.
 
 Import this shell with ~nix develop $DOTFILES#cc~
 
@@ -421,6 +473,10 @@ mkShell {
 #+ATTR_LATEX: :width 400px
 [[./docs/images/python.png]]
 
+#+BEGIN_SRC python
+print("Hello, world!")
+#+END_SRC
+
 [[https://python.org][Python]] is an interpreted high-level, general-purpose programming language. Its design philosophy emphasizes code readability, with its notable use of significant indentation. Its language constructs, as well as its object-oriented approach aim to help programmers write clear, logical, code for small and large projects.
 
 Import this shell with ~nix develop $DOTFILES#python~