It's always hard to parse if people mean functional programming when bringing up Lisp. Common Lisp certainly is anything but a functional language. Sure, you have first order functions, but you in a way have that in pretty much all programming languages (including C!).
But most functions in Common Lisp do mutate things, there is an extensive OO system and the most hideous macros like LOOP.
I certainly never felt constrained writing Common Lisp.
That said, there are pretty effective patterns for dealing with IO that allow you to stay in a mostly functional / compositional flow (dare I say monads? but that sounds way more clever than it is in practice).
> It's always hard to parse if people mean functional programming when bringing up Lisp. Common Lisp certainly is anything but a functional language. Sure, you have first order functions, but you in a way have that in pretty much all programming languages (including C!).
It's less about what the language "allows" you to do and more about how the ecosystem and libraries "encourage" you to do.
But most functions in Common Lisp do mutate things, there is an extensive OO system and the most hideous macros like LOOP.
I certainly never felt constrained writing Common Lisp.
That said, there are pretty effective patterns for dealing with IO that allow you to stay in a mostly functional / compositional flow (dare I say monads? but that sounds way more clever than it is in practice).