Python 3

both tabs & spaces allowed for indentation And you'd think people learn from the past (Makefile). Just pick spaces and forbid tabs. YAML got it right. lack of popular third-party libraries The standard library is great, but a lot of what makes Python 2 so powerful lies in the third-party realm. Python 2 got this right :-). IEEE floats Floating points in programming languages are confusing because they're different from the way we use them in math. Instead, the number operations should be viewed as expressions that are only converted to a decimal point format when needed (i.e. printing to a screen). Maple and Mathematica did this right I think. the character set for identifiers is too restricted list.empty? is better than list.is_empty or even len(list) != 0. Similarly, process.kill! would be better than process.kill. Ruby and lisp got this right. when calling a function you must always write parentheses It would be nice if we could omit them in unambiguous cases. How is it again? dict.items or dict.items()? Ruby got this one right, too.

PHP:

人们永远无法确定某些几乎常见的扩展在所有web服务器上都可用。 试图成为未来的一切(goto，闭包，…) 对于没有经验的用户有很多安全风险 更多的操作符重载会很好 所有不学习如何使它正常工作的可怜的程序员，给它一个坏名声

尽管如此，PHP是(脚本)语言。: -)

Clojure

Lack of built-in syntax for optional and keyword parameters in function definitions. Sure, you can add it easily enough, but that means library writers don't use it. Pervasive destructuring hasn't proven to be a good substitute yet Lack of method combination (before/after/around methods of the sort found in Common Lisp) Too much reliance on Java interop, e.g. there's no built-in file IO Sometimes I want static typing. This one isn't pure hate; I usually prefer dynamic, and attempts to mix the two have been largely unsatisfactory There's no built-in fast binary serialization format for the built-in data structures, though I hear people are working on it

C#.

我最讨厌的是:

No multiple inheritance - imagine you could provide whatever GUI framework base class (Control, Window, whatever) with MVC - related stuff, etc... framework / base class agnostic! No "friend" keyword... I know, the RAD - victims would abuse it for all kinds of stinky code and for hilarious malpractices, but it would be nice for the OOD - guys to enforce the law of demeter No language integrated DBC features, there are the Contracts, but I would rather have that Spec# - style with a general purpose "!" - postfix operator No AOP (I don't get it... this language has attributes, it would have been SO EASY to add interception code in the compiler!) No weak event delegates - the observer pattern becomes nothing but a memory leak bait as it is now... :-(

Common Lisp

conditions aren't classes (since classes came later), even though their interface is almost identical some of the names are just weird, e.g., flet / labels (only difference: scope), and defvar / defparameter (only difference: behavior when already defined), or any of the bit-twiddling functions (dpb, ldb, etc.) packages are ... really hard to get right -- every time I think I understand them, they don't do what I want built-in data structures and functions aren't as generic as they could be (e.g., why can't I define my own hash function portably?) multiple namespaces for functions, variables, etc. (I'm not opposed to this in principle, but CL made it too complex; Norvig has said he can't tell from the spec but there appear to be at least 7 namespaces)

Ruby。

Strange scoping rules - variables, constants, and methods each behave differently from each other. The rules change also depending on which keyword you used to create a closure. Or on whether you're in a class, eigenclass, object, module, or module's self. Then there's instance_eval, which changes the rules to a different set of rules. And they change again when a module is "included" or "extended", which themselves do different things to scope. And some sets of rules can't be emulated by metaprogramming, so you have to use eval. Unless you're on ruby 1.9, where all of this is different. Namespacing is basically useless. If you have Foo::File, then the stdlib File is probably broken for all of Foo. require statement is broken. If two files require eachother, the behavior of those files can change dramatically depending on which is loaded first from elsewhere. libraries change APIs dramatically and suddenly, so you have to require specific minor revision numbers of all of your dependencies. For every single ruby application on your system. The rubygems package system overrides "require" rather than putting files in the search path - because why use a system when you can replace it?