Editing Empty product (section)

== In computer programming ==
Many programming languages, such as [[Python (programming language)|Python]], allow the direct expression of lists of numbers, and even functions that allow an arbitrary number of parameters. If such a language has a function that returns the product of all the numbers in a list, it usually works like this:
<syntaxhighlight lang="pycon">
>>> math.prod([2, 3, 5])
30
>>> math.prod([2, 3])
6
>>> math.prod([2])
2
>>> math.prod([])
1
</syntaxhighlight>
(Please note: <code>prod</code> is not available in the <code>math</code> module prior to version 3.8.)

This convention helps avoid having to code special cases like "if length of list is 1" or "if length of list is zero."

Multiplication is an [[infix notation|infix]] operator and therefore a binary operator, complicating the notation of an empty product. Some programming languages handle this by implementing [[variadic function]]s. For example, the [[S-expression|fully parenthesized prefix notation]] of [[Lisp programming language|Lisp languages]] gives rise to a natural notation for [[nullary]] functions:

 (* 2 2 2)   ; evaluates to 8
 (* 2 2)     ; evaluates to 4
 (* 2)       ; evaluates to 2
 (*)         ; evaluates to 1