Wikipedia says: 'The syntax [of an AST] is "abstract" in not representing every detail appearing in the real syntax.' So relating to Lamdu, you could say that

Wikipedia says: 'The syntax [of an AST] is "abstract" in not representing every detail appearing in the real syntax.' So relating to Lamdu, you could say that what you see is the abstract representation. The representation is a bitmap, of course you can't evaluate that. When you write C++, you actually just write characters, right? Does that mean that you are not writing a program? No, those characters may comprise a program in the end. I see Lamdu the same way: Even though you only manipulate a graphical rendering of the program, it still is all you need to write that program. Just like with C++, you don't see the actual representation of the program (because you can't really 'see' a data structure, you need to encode it), you only see the characters, but you can write the program anyway. Lamdu is a purely functional programming language so far, I believe. You don't need input, since you can, in the one expression you have available, call a function with arbitrary parameters. You can say that it does not allow for long-running interactive programs, but that is easy to add later once the foundations are in order.