Hello world: simple console output

A good feature to learn first in any language is how to print things out to the console. Although Chapel has a sophisticated set of I/O features, let’s just focus on a simple capability to get started.

The writeln() procedure prints its list of comma-separated arguments to the console, one after the other without spaces, followed by a newline. Thus, the following statement will print a greeting to the console:

writeln("Hello Chapel Users!");

This guide will cover the Chapel program structure in more detail later; for now, it’s sufficient to know that a Chapel program can simply be a sequence of statements in a file. Thus, the statement above is a complete Chapel program. If you type or paste it into a text editor and save it into a file, say hello.chpl, you’ll have written your first Chapel program.

Given a working Chapel compiler (see Downloading Chapel for details), you can compile the program using:

chpl hello.chpl -o hello

which says to compile the hello.chpl Chapel source file, naming the output binary hello. Once the compiler is done, you can run the program using:


The program should then print the greeting to your console as follows:

Hello Chapel Users!

And with that, you’ve executed your first Chapel program!