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

Python

1-3:没有一个明显的打包/构建/文档系统的选择(比如Perl的cpan、POD或Ruby的gem、rake、rdoc)。 4: Python 3.0是不兼容的，需要两个源分支(2。x和3.x)用于每个Python项目。但是Python 3.0的不兼容性还不足以证明它的合理性。大多数py3k的优势都太微妙了。 5: Jython, IronPython, CPython不兼容。

但这只是因为VB6毒害了整整一代程序员

我在一个曾经是VB6商店的VB . net商店工作，而在这里工作的每一个曾经是VB6开发人员的人都顽固地拒绝学习任何关于. net的知识。他们编写的代码就像VB6一样，他们的应用程序就像VB6应用程序一样糟糕。我的老板非常不鼓励使用LINQ，因为她担心其他人很难理解，这是事实，因为没有人想要理解它。

我认为如果微软只使用c#，我们会过得更好，这让我很难受，因为我认为花括号远不如VB的冗长结束语句。

Python:

Global Interpreter Lock - Dealing with this complicates parallel processing. Lambdas functions are a bit clunky. No built-in ordered-dictionary type. Depending on how Python is compiled, it can use either UCS-2 vs UCS-4 for the internal Unicode encoding, many string operators and iterators may have unexpected results for multi-byte characters that exceed the default width. String slicing and iteration depend on the bit width rather than checking and counting characters. (Most other programming languages do similar things as well and have similarly odd behavior with these characters.) There are inconsistencies surrounding GUI frameworks for Python.

c# / .net:

Classes should be sealed by default There should be no lock statement - instead, you should have specific locking objects, and there should be methods such as Acquire which return disposable lock tokens. Corollary: there shouldn't be a monitor for every object. GetHashCode() and Equals() shouldn't be in System.Object - not everything's suitable for hashing. Instead, have an IdentityComparer which does the same thing, and keep the IComparer<T>, IComparable<T>, IEqualityComparer<T> and IEquatable<T> interfaces for custom comparisons. Poor support for immutability Poor way of discovering extension methods - it should be a much more conscious decision than just the fact that I'm using a namespace.

这些都是我想出来的，明天问我，我会想出一个不同的5个:)

JavaScript:

The Object prototype can be modified. Every single object in your program gets new properties, and something probably breaks. All objects are hash maps, but it's difficult to safely use them as such. In particular, if one of your keys happens to be __proto__, you're in trouble. No object closure at function reference time. In fact, no object closure at all -- instead, this is set whenever a function is called with object notation or the new operator. Results in much confusion, particularly when creating event callbacks, because this isn't set to what the programmer expects. Corollary: calling a function without object notation or the new operator results in this being set equal to the global object, resulting in much breakage. Addition operator overloaded to also perform string concatenation, despite the two operations being fundamentally different. Results in pain when a value you expect to be a number is in fact a string. == and != operators perform type coercion. Comparisons between different types involve a list of rules that no mortal can remember in full. This is mitigated by the existence of === and !== operators. Both null and undefined exist, with subtly different, yet redundant meanings. Why? Weird syntax for setting up prototype chains. parseInt(s) expects a C-style number, so treats values with leading zeroes as octal, etc. You can at least parseInt(s, 10) but the default behaviour is confusing. No block scope. Can declare the same variable more than once. Can use a variable without declaring it, in which case it's global and probably breaks your program. with { }. Really difficult to document with JavaDoc like tools.