[dathinab]

> first popularized by certain functional languages

Basically that.

People associate all kinds of different thinks with the term functional programming. The only think in common is that it's focused on functions, including first class functions.

For other thinks including things like (strict) immutability, lazy evaluation, syntax, algebraic data types, linear typing, etc. it is different from person to person weather or not they think about this as part of FP or just another think which happens to be part of the FP language they use/looked into.

[gameswithgo]

A lot of those things are natural consequences of having functions without side effects though. Lazy evaluation for instance, can be bonkers if your functions have side effects.

[agumonkey]

It's not only 'first' but also immutable as a way of life.

You walk structures to extract information and derive a new structure. With immutable types and automated constructors this becomes regular enough to be baked in the language. Other languages like memory mutation so the main action is setting a variable to modify it.