General
Functional Programming
Also written as FP
A programming paradigm built around pure functions and immutable data — avoiding shared state and side effects — as an alternative (or complement) to the object-oriented model. Core to languages like Haskell and Scala, and increasingly common as a style within JavaScript, Python, and others.
Think of it like
Like a recipe that never touches the original ingredients — every step produces a new dish, leaving the pantry exactly as it was — instead of one shared pot everyone stirs into.
Junior or senior?
Junior sounds like
Cites 'no side effects' as a buzzword.
Senior sounds like
Can name a concrete bug that immutability or pure functions would have prevented.
Ask them
“Tell me about a bug caused by shared mutable state. Would a more functional approach have prevented it?”