What is a good, simple scripting language to embed into a macro-processor

I want to write a macroprocessor. So far I've done a very simple sketch of how it should look and I came to the conclusion that inventing a completely new language would not be a good idea but I should reuse existing concepts. My sketch so far is a kind of irb with some tex-alike syntax and features, but I'm not sure what I should use as ruby-substitute. The language should be simple, yet powerful. I don't want to write an OS in it, but it should be less "raw" than e.g. bc or forth. I don't care about execution time at all. Embedding should not be too hard and it'll be nice if the language itself was stable.

So far I've considered these:

• Lua - It should process text easily. Lua does not even have a while(c=getchar()){}. I'm skeptic.
• awk - Simple, text processing is easy, but never intended for embedding
• perl - Way to complex, stable, but it seems almost dead.
• python - Significant whitespaces; won't they get in the way for inlined function-definitions?
• groovy/nice/java - Hard/impossible to embed? Also way to heavy.
• javascript - Really like it (besides DOM) but is there a stable/embeddable implementation? I don't want to mess around with the api every 2 weeks when there's a new v8 version. As I said, I don't care about execution time.

I have not really found any pros/cons for

• io
• guile/scheme
• TCL

Update: The language should have features such as function-definition, library-loading or regexps (loops would also be very nice) I don't want to use a traditional macro-language such as M4 because I want to able to write in a more procedural (or maybe functional) style. Macro languages have their pros, but I requires a completely new way of thinking about a problem which is hard especially 开发者_JAVA百科for beginners. My Aim is to use the best of both worlds.

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Given that TCL is about string and array processing, and is intended for embedding, it would seem an obvious choice.

Luatex has a certain following. Presumably they have found a way to make it work for text processing, so you might like to look at that.

Scheme (including guile) is also very nice for scripting; alternatively you might look at whether there is a way you could embed an elisp processor (embed xemacs?), which after all is all about text processing.