Hello, World
The way to learn a language is to write programs in it, and following the time worn traditions of the greats, our first program to write is one that will print the following words: `"Hello, world".
Once we have accomplished that, we've got a good starting point: The system is set up, and everything is working. So, type in the text below, or run it online if you so desire:
Type it into a file. The name doesn't matter, as long as it ends with
the .myr suffix. I'm going to put mine into hello.myr.
To compile it, the mbld program that ships with Myrddin can be run like so,
from within the directory that contains your hello.myr file:
mbld -b hello hello.myr
Something that resmebles following output should show up on your screen:
hello...
6m hello.myr
ld -o hello hello.o -L/home/ori/bin/lib/myr -lstd -lsys
The details of the output may vary by system, but at the end of the process,
and an output binary will be created in the directory in which you ran mbld.
When you run the binary, you should get the following output:
$ ./hello
Hello World
The command mbld is the Myrddin build tool, and is responsible for invoking
the appropirate compiler and linker commands in the correct order. It can be
configured directly from the command line, or configured via a file. For simplicity,
we will be using the command line configuration options.
The -b name option tells mbld to produce a binary named name, and the
remainder of the arguments are the inputs to combine into the binary. Any
arbitrary name can be selected.
Now that the code is working, an explanation is due. A Myrddin program
consists of declarations, types, and statements. A function is a sequence of
statements, enclosed by {' and}, which are executed in order. In this
example, there is one declaration -- the constantmain, which is initialized
with a simple function containing one statement. Normally, functions can be
named anything, although themainfunction, when not in a namespace, is
special, since every program begins executing at the beginning ofmain`.
The first line of the program,
use std
brings a number of declarations into scope. These declarations include
the function put, which is used to output data to the terminal. The
constents of libstd are described in full here.
The declaration of main is slightly interesting, because unlike most languages, there is no distinction in Myrddin between function declarations and variable declarations. A function decaration is simply a constant with a function assigned to it, and a function is always an unnamed list of statements within curly braces.
const main = {;...}
In this example, the main function takes no parameters, as signified by the
lack of parameter names listed before the first ; in the function.
The body of the main function
std.put("Hello World\n")
contains a single statement. This statement is a function call, calling
the function put defined within the library std, passing it a single
parameter, the string "Hello World\n".
Within a function body, any number of statements can be placed. So, for example, if we had written
the code would have executed both statements in the sequence denoted in the text.
Another feature to note here is the text enclosed within /* and */.
This text is known as a comment, and is ignored by the compiler. It is
used so that you, the programmer, can make notes to yourself.
Statements will be covered in more depth in the next section of the tutorial