Could you elaborate on this a bit? Basically calling a functions form an other is how a step-by-step algorithm would work in FP, no? And pattern match on what comes in, and return an immutable copy.
For example you can put functions in a list, and push a datastructure through them, like a pipeline.
The control structure that takes the different functions/values and glue them together is what makes your code imperative or descriptive. While there is a lot of overlap between descriptive style and fp, it is not always the case.
In haskell, for instance, the do notation lets you write imperative code:
f article = do
x <- getPrices article
y <- book article
finishDeal article x y
...and then the compiler desugars it to a more descriptive form.
In fairness, we could be in the List monad here, and this would effectively be a list comprehension rather than an imperative program. Even if we are in IO, `getPrices` and `book` may never execute --- even `finishDeal` may never execute! --- depending on non-local details that aren't shown here.
The code certainly "looks imperative" but it's still a declarative program --- the semantics are rather different from what a typical "imperative programmer" would expect.
For example you can put functions in a list, and push a datastructure through them, like a pipeline.
edit: https://probablydance.com/2016/02/27/functional-programming-...