Hello, World!
Now that you have installe Whistle on to writing your first program! The program
will print Hello, World! to the console as per tradition when writing your first
program in a new programming language.
Writing and Running your first Whistle Program
The first step in creating a Whistle program is creating a new file with the
extension .whi to signify that it is a Whistle source file. This file will
be tokenized, parsed and finally compiled by the Whistle compiler.
In this case a new file called HelloWorld.whi will be created with the following
content:
All we need to do now to run the program is to run the following in your terminal:
And the following output should appear in your terminal:
If Hello, World! did print, congratulations! You’ve officially written a
Whistle program. If it however did not print your installation most likely
did not succeed or your PATH does not include the ~\.deno\bin directory.
Explanation
The Hello, World! program shows quite a few of Whistles design choices and
how to use some of the basic features of Whistle.
The first important piece of the program is the function declaration declared
using the fun keyword. This tells the parser to
expect the name or so called identifier of the function. After this an optional
parenthesis enclosed part comes which specifies all of the parameter names and
their respective types. Before the last part which is the actual function body
statement the return type of the function is specified.
When the function declared is supposed to be accessable from other files than
the one it is specified in the export keyword can be used to prefix the function
declaration like this: export function example: none { ... }.
"Tips" in Whistle are specified by using the #( ) ... syntax (or #( ) { ... }#
for inline or multiline "tips"). They are a way of telling the compiler things
about your code such as telling it to insert the raw javascript code directly into
a program compiled to javascript.
In our case this tells the compiler to call the javascript method console.log
directly to print our text parameter to console.
Finally we come to the last part of the Hello, World! example, a function call statement which calls the
function previously declared. It does this by first specifying the identifier of
the function to call (in this case log) and then enclosing all of the parameters
to pass to the function in parethesis separated by commas.