Question

what is the difference between pure and impure function

Answer 1

Pure function

1.The return value of the pure func­tions solely depends on its arguments Hence, if you call the pure func­tions with the same set of argu­ments, you will always get the same return values.

They do not have any side effects like net­work or data­base callsThey do not mod­ify the argu­ments which are passed to them

Impure function

The return value of the impure func­tions does not solely depend on its arguments Hence, if you call the impure func­tions with the same set of argu­ments, you might get the dif­fer­ent return values For exam­ple, Math.random(), Date.now()They may have any side effects like net­work or data­base callsThey may mod­ify the argu­ments which are passed to them

Answer 2

Pure function takes place in Call by Value
Impure function takes place in Call by Reference
In pure function it doesn't modify the external variable/data outside the scope and results the same output given in the same input.

In impure function it mutates data/variable outside it's lexical scope Hope this helps..