Compile and Run commands for swift

Open the terminal and type:

sudo apt install clang libicu-dev -y
wget https://swift.org/builds/swift-4.2.3-release/ubuntu1804/swift-4.2.3-RELEASE/swift-4.2.3-RELEASE-ubuntu18.04.tar.gz
mkdir ~/swift
tar -xvzf swift-4.2.3-RELEASE-ubuntu18.04.tar.gz -C ~/swift
nano ~/.bashrc

.bashrc will open in the terminal for editing in nano text editor. Paste the following line at the end of .bashrc.

export PATH=~/swift/swift-4.2.3-RELEASE-ubuntu18.04/usr/bin:$PATH

Press the keyboard combination Ctrl+O and after that press Enter to save the file being edited. Press the keyboard combination Ctrl+X to exit nano.

Close the terminal, open a new terminal, and run the following commands.

swift -version # This command should print Swift version 4.2.3.
cd Desktop/
mkdir helloworld-project && cd helloworld-project
swift package init --type executable
swift build
.build/debug/helloworld-project

Results:

Hello, world!

Swift REPL example 1

Swift has an interactive interpreter called the REPL which stands for Read-Eval-Print-Loop. The REPL can be run interactively from the command line as demonstrated in the below example.

$ swift -repl
:0: warning: unnecessary option '-repl'; this is the default for 'swift'  
with no input files
Welcome to Swift version 4.2.3 (swift-4.2.3-RELEASE). Type :help for assistance.
  1> // Hello, World! Program
  2> import Swift
  3> print("Hello, World!")
Hello, World!
  4> :exit

Swift REPL example 2

This example executes the same code as example 1 with two differences.

1. Everything is done in Gedit.
2. The entire code block is copy/pasted from the edit pane into the terminal pane in Gedit (Embedded Terminal plugin), and run by the Swift interpreter as a block of code instead of one line at a time.