DMD also comes with a built in D interpreter, RDMD, allowing you to use D as a scripting language with a compiled binary. This can be embedded or called from your D program allowing your program to have a scripting layer written in the same language as the compiled binary. As far as I know, executing a .d file with RDMD is nearly as fast as running a compiled binary.
I've read about D's compile time evaluation but have no personal experience. I know both Rust and C++ are pushing in the same direction.
From what I can see, it's simply an embedded interpreter for the same language; which means that it probably runs about as fast as interpreters in general (that is, significantly slower than D). I would love to be wrong and learn something new, though.
Starting from an interpreter means it's already there, the only difference is when code is evaluated. And embedding it simply means linking the interpreter library. Snigl and D are sort of approaching Lisp from different angles.
