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0 pointsnnq13y ago0 comments

...indeed, the one thing I "hate" about Python is that somehow it pushes your mind away from functional solutions. You end up writing either OO or procedural code, although in a language with first class functions and immutable strings you's expect to slip more to the functional side.

Anyone else had the feeling that although Python allows functional style, it somehow pushes your mind away from it?

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5 comments · 2 top-level

betterunix13y ago· 2 in thread

Well it does not really help that Python lacks tail call elimination (last I checked), which is fairly important to (practical) functional programming.

calpaterson13y ago

Meh, you'd use fold, map or filter 99% of the time in a functional language like scala or haskell. TCO is great, but you can still write a lot of idiomatic functional stuff even without it.

jholman13y ago

Right! TCO is not essential to practical functional programming. TCO is essential to practical use of the subset of functional programming that insists on recursion instead of iteration, including fold/map/filter.

TCO is an under-the-hood behaviour that the programmer would count on for practical performance. There's no reason that under-the-hood magic can't be in the implementation of fold/map/filter as primitive control ops.

It's just an accident of history that the [mp]atriarch functional programming language is Lisp, a language that was created in the name of proving a point about recursion. Recursion as the solution-to-all-problems is not essential to functional thinking. The essential ideas are first-class functions, higher-order functions, and referential transparency.

I think this mistake is comparable to thinking that classes are essential to object-orientation. I think many people are confused by university professors who love Scheme (for reasonable reasons), and who like to pretend that Lisps are the only alternatives to Fortran (arguably true in the '60s).

vaughan013y ago· 1 in thread

Personally I find myself avoiding writing in a functional style in Python because of it's lack of good anonymous function literals and poor handling of closures in nested functions.

Edit: when I say "poor handling of closures in nested functions" I'm referring to having to use nonlocal in order to modify variables in the parent function's scope.

nnqOP13y ago

yeah, I think lack of real anonymous functions is a small annoyance that can get quite "big" from the yucky feeling you get when defining functions just to pass them on. But... what do you mean by "poor handling of closures in nested functions"?

Edit: ok, I get what you mean now :) ...though I consider this "poor handling" a feature of Python - mutating outer scope variables is a side-effect and what it encourages is what I like to call "callback hell functions with data Javascript-style nightmare" :) (true, some people know to keep their sanity and write readable code even in this style, and if you enjoy it you're probably one of them few, but most don't...). By "functional style", I and some people refer to "functional as in mathematical functions", so only using side-effects when actually needed (yeah, some "extremist" languages like Haskell try to never do them, but...) and you get this by having immutable values and passing around anonymous functions (that don't modify their outer scope).

...and this is another part of the paradox: this "feature" of Python should encourage what I call functional style, but why oh why it doesn't? ...maybe Rich Hickey is on to something with Clojure and it's actually more about the data-structures than the language syntax or semantics?

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