I think it's broadly misunderstood, and there is usually a conflation of 'functional programming' with a 'functional programming style'.
The functional programming style is generally procedural abstraction, with an aspiration to avoid side effects, but misses the fundamental qualities of functions.
But without understanding the fundamental qualities of functions, it's hard to know where and when it's appropriate, which leads to a general devolution into superstition and mythology. :)
Which is why I always bring it back to time -- it isn't time invariant, it isn't a function.
Once you understand this, everything else flows naturally from this fundamental property.
I think it's broadly misunderstood, and there is usually a conflation of 'functional programming' with a 'functional programming style'.
The functional programming style is generally procedural abstraction, with an aspiration to avoid side effects, but misses the fundamental qualities of functions.
But without understanding the fundamental qualities of functions, it's hard to know where and when it's appropriate, which leads to a general devolution into superstition and mythology. :)
Which is why I always bring it back to time -- it isn't time invariant, it isn't a function.
Once you understand this, everything else flows naturally from this fundamental property.
You have explained this extremely well. Excellent points - all of them.