Five Things I Hate (or at least dislike) About Python

1. Implicit Variable Creation

This is probably my biggest complaint. Why would you want to implicitly create a variable the first time something is assigned to it? This might make sense in a language where variables are immutable by default (after all, you only ever assign a variable once), but Python isn't. Also, I realize there is a technical difference between rebinding names and changing the value of a variable; I don't find that particular distinction useful here.

2. Dearth of Collections (in the standard library)

Don't get me wrong: defaultdict and namedtuple are nice, but on occasion I really find myself wishing for some more advanced data structures, e.g., Red-Black tree. I'm not even talking about probabilistic structures like Bloom filters or skip lists.

3. Lack of Tail-call Elimination

I know it likely won't happen, but I still wish I had it. To me (and I'm sure many others), recursive algorithms are the most natural way to express certain algorithms, e.g., traversing a tree. I can do it using a loop, but it really drops me out of the zone.

4. Concurrency in the Standard Library

In an ideal world, Python would support concurrency on a level with first-class functions, similar to Erlang. It's almost not even fair to ding Python on this, since pretty much every other language its age has the same problem, but a man can dream, right? At least the multiprocessing module made it into the standard library.

5. Interfaces

It would be really swell if Python had support for something like interfaces. I know that PEP 3119 introduced Abstract Base Classes, so this one is probably on the way to being remedied, but the feature is so new I haven't yet encountered it in the wild.

Back to flipping out...

Five Things I Hate About Java

I'm sure you've all seen the Five Things meme. Here's the five things I hate about Java.

1. Lack of Type Inferencing

There's just enough generics-related type inferencing to leave me wanting more.

2. No First-class Functions

I don't care if there are patterns for doing this, it's not very idiomatic, and the boilerplate obscures the intent of the code, which largely defeats the purpose.

3. No Read-Eval-Print Loop (REPL)

I can't praise the REPL enough. Java should have had one of these in the JDK in 1.0.

4. Checked Exceptions

The standard library is riddled with checked exceptions that really should have been unchecked, and third-party libraries have followed suit. In fact, Exception should have been unchecked and we should have CheckedException as a subclass instead of RuntimeException.

5. Array Covariance

It's broken. Especially now that Java has covariant returns (thanks Java 5!), this bothers me just often enough that I've forgotten how broken it is right before I need/want it.

Honorable Mention: No Tail-call Elimination

This very nearly bumped Array Covariance. I really wish tail-call elimination would catch on in mainstream languages.

Back to flipping out...