Nope. For example, you can't parse HTML or source code with a regular expression, because of limitations on how the language itself works (it doesn't have the ability to parse nested structures).<p>However, in practice, most common programming languages can be used to implement other programming languages...it's just a matter of how much/little code you're going to need to write to do it. Using this article as an example, it would be much easier to implement Scheme in F# than it would be in C#, due to some features of the F# language.