Constants in Mercury

Our example will demonstrate the use of constants. In the provided example, we’ll declare a few constants and perform arithmetic operations on them. Here’s the full source code.

import math

# Declares a constant value
S = "constant"

def main():
    print(S)

    # A constant statement can appear anywhere a var statement can.
    N = 500000000

    # Constant expressions perform arithmetic with arbitrary precision.
    D = 3e20 / N
    print(D)

    # A numeric constant has no type until it’s given one, such as by an explicit conversion.
    print(int(D))

    # A number can be given a type by using it in a context that requires one, such as a variable
    # assignment or function call. For example, here math.sin expects a float.
    print(math.sin(N))

if __name__ == "__main__":
    main()

To run the program, save the code in constants.py and use python to execute it.

$ python constants.py
constant
6e+11
600000000000
-0.28470407323754404

Now that we can run and understand the basics of constants, let’s learn more about the language.

Variables in Mercury

For in Mercury

Learn X By Example

Title here

Constants in Mercury