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。: -)

PHP

几乎每个标准函数都在全局作用域中 不一致的函数参数顺序 不一致的函数命名 不区分大小写的函数 脚本的行为可能会因php.ini文件的不同而有所不同 能够使用未定义的变量 在某些情况下，必须将结果赋值给变量，然后才能在函数中使用它

更主观地说:

动态类型

F#

Type inference is limited. It propagates forward only. F# won't try to infer an object type based on the methods and properties used: you'll get "lookup of indeterminate object type" errors when it doesn't have a clue. One cannot mix floats and ints: 1 + 2.3 is a type error. It's a little awkward to have to create a builder object in order to define a monad or computation expression. In Haskell or Scala, you can define the monad operations directly on the monadic object. Though the #light syntax is preferred, the indentation rules are sometimes not very intuitive or become cumbersome.

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:)

Ruby

无类型推断 方法/函数不是一级对象 变量的范围不是词法的，尽管块变量的范围是词法的 Def内部的Def super和super()的区别

闲聊

我不想再用java、delphi、c#或ruby进行开发(这是不切实际的，因为我公司的主要开发语言是c#、delphi和java)。 从左到右的评估。 有类注释但没有方法注释(至少在Squeak中) 没有真正的标准库，在细节上有很多差异 缺少名称空间