Compile using blc and run ./out.

// Global variable is visible in whole source. This variable is initialized
// by constant literal '10' which is known in compile time.
MyGlobal : s32 = 10;

// Global immutable variable
CannotChangeThis : f32 : 10.f;

// Global without initialization will be automatically set to it's default
// value, in this case it's zero.
DefaultValueGlobal: s32; 

main :: fn () s32 {
    // Local variables are declared in local scope of main function or
    // any other function.
    number : s32 = 10; // This is number of s32 type set to 10.

    number = 20; // Number is mutable, and since now it's value is 20.

    // Use of the print function to print out variable value.
    // '%' is used as placeholder in the string saying where the print 
    // function should place our value.
    print("number is %\n", number);

    // Variable without initialization will be automatically set to default
    // value. In this case 'other_number' will be zero. This initialization
    // can be disabled by #noinit flag 'other_number: u8 #noinit;'.
    other_number: u8;
    other_number = 16;

    print("other_number is %\n", other_number);

    // Type of the variable can be inferred from type of initialization 
    // value.
    boolean := true; // Inferred bool type.

    // We can print bools in the same way as numbers.
    print("boolean is %\n", boolean);

    // Declare local immutable number
    immut_number : s32 : 10;

    // This is illegal, variable is immutable.
    // immut_number = 10;
    print("immut_number is %\n", immut_number);

    // Or just do this...
    immut_other_number :: 20;

    print("immut_other_number is %\n", immut_other_number);

    return 0;