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Terms for types of functions with respect to side effects
Mathematically, the purpose of a function is to return an output. However, in a programming context functions often have side effects. It is even common to call functions for the side effects alone. The classic example is
print(x), which has a useful side effect and no output.
It seems to me that we can taxonomize functions into five classes based on human expectations about their outputs and side effects:
- Functions with no side effects, where the output is most interesting
- Functions with side effects, but the output is most interesting
- Technically, all functions are like this, because running things on the computer always has side effects like using up CPU and RAM.
- Functions with an output, but the side effect is more interesting than the output
request(url, type="POST")- the output is only a detail if we care to check whether the request succeeded, which may even be irrelevant in some cases
- Functions with no output, executed for their side effects
- Functions with no output or side effect to speak of (usually created for testing or as placeholders)
Is there a terminology for these classes?