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Reserved keywords

The following words are reserved and cannot be used as identifiers:

and by case do else end export extern for function global if import in include inline loop nil not object of on or otherwise repeat return task tell then to until when while

Comments

To write comments, use the character #. Any text from this character to the end of the line is ignored. Each line to be commented must be preceded by the # character, i.e. C-like multi-line comments are not allowed.

Macro comments
# Now plot the field
plot (Z500) # using default contours 

Functions

You can define your own functions  in Macro. Functions can take any number of input arguments and can optionally enforce type-checking on them. A function does not need to have a return value. Only one value can be returned - to return multiple values, return a structure such as a list, vector or definition containing the values.

The following examples show how to write functions in Macro. 

# function that takes no arguments
function always_return_5 ()
    return 5
end always_return_5

five = always_return_5()


# function that takes an argument and does no type-checking
function add_10_untyped (a)
    return a+10
end add_10_untyped

b = add_10_untyped(4)


# function that takes two arguments
function add_two_untyped (a, b)
    return a+b
end add_two_untyped

b = add_two_untyped(9, 11)


# function that takes an argument that must be a number
function add_10_to_number (a:number)
    return a+10
end add_10_to_number

b = add_10_to_number(6)
b = add_10_to_number('Hello')  # Run-time error


# function that returns a list of four values
function return_4_values_as_list(a)
    return [a+4, a+3, a+2, a+1]
end return_4_values

b = return_4_values_as_list(10) # [14,13,12,11]


# return four values as named elements of a structure
function return_4_values_as_definition(a)
    return (w: a+1, x: a+2, y:a+3, z:a+20)
end return_4_values_as_definition

b = return_4_values_as_definition(10) # (w:11,x:12,y:13,z:30)


# function that takes any number of arguments
function print_all_params
    loop arg in arguments()
        print(arg)
    end loop
end print_all_params

print_all_params(5, 6, 7, 'Hello')


Loops, tests & functions

Please check this handout: macrotut_syntax.pdf

Macro tutorial

To learn more about the Macro syntax, please follow the Metview Tutorials.

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