Assignment and values

The assignment operator in MEL is the equal sign (=). MEL also has shortcut assignment operators like C and Java (+=, -=, /=, *=, ++, --, etc.).

MEL is a strongly typed language, however it allows implicit declaration and typing in most instances. When you declare a variable you also declare its type and can optionally assign an initial value.

Variable names start with a $, followed by a letter, then any combination of letters, numbers, and underscores. Unlike PERL, all types of variables (scalar and compound) start with $.

MEL has the usual integer (int), floating point (float) and string data types. It also has a vector data type which is a triple of floats (which can be useful when working with 3D data), arrays (a variable-sized list, in which all elements are of the same type), and matrices (matrix, a fixed-size two dimensional table of floats). Items in an array must all be of the same type.

int $a = 5;
float $b = 3.456;
vector $v = <<1.2, 3.4, 6.5>>;
float $ar[] = {1.2, 3.4, 4.5}; // An array of floats
matrix $mtx[3][2]; // A 3x2 matrix of floats

You cannot make an array of arrays in MEL.

MEL automatically converts types whenever possible.

Control and looping statements and operators

MEL’s control statements are very similar to C and Java.

if ( $a == $b) {
	...
} else if ($a > $b) {
	...
} else {
	...
}
$a = ($b > 10) ? $c : ($c - 10);
switch ($color) {
 case "blue":
 ...
 break;
 case $c1:
 ...
 break;
 default:
 ...
 break;
}
while ($a < size($arry)) {
	...
}
do {
	 ...
} while ($a > 0);
int $i;
for ($i = 10; $i > 0; $i--) {
	print($i+"...\n");
}
print("Blastoff!!!");
string $arry[3] = {"red","green","blue"};
for ($k in $arry) {
	...
}

Defining and calling procedures

You create user-defined procedures using the following syntax:

global proc <return type> <name>(<arg list>) {
	...
	return <exp>;
}
global proc float squareAndAdd(float $x, float $y) {
	return $x * $x + $y;
}
square(5.0, 2.0);
27

If you leave out the global keyword the procedure is only available in the script file in which it is defined.

If the procedure does not return a value, leave out the return type keyword and do not include a return statement.

global proc msg() {
	print("Hello world\n");
}