At the risk of telling you what you already know and/or did not mean to say: not everything can be a value. If everything is a value then no computation (reduction) is possible. Why? Because computation stops at values. This is traditional programming language/lambda calculus nomenclature and dogma. See Plotkin's classic work on PCF (~ 1975) for instance; Winskel's semantics text (~ 1990) is more approachable.

Things of course become a lot more fun with concurrency.

Now if you want a language where all the data thingies are immutable values and effects are somewhat tamed but types aren't too fancy etc. try looking at Milner's classic Standard ML (late 1970s, effectively frozen in 1997). It has all you dream of and more.

In any case keep having fun and don't get too bogged in syntax.

"Everything is a value" is not very informative. That's true of most languages nowadays. Maybe "exclusively call-by-value" or "without reference types."

I've only read the first couple paragraphs so far but the idea reminds me of a shareware language I tinkered with years ago in my youth, though I never wrote anything of substance: Euphoria (though nowadays it looks like there's an OpenEuphoria). It had only two fundamental types: the atom, a possibly floating point number, and the sequence: a list of zero or more atoms and sequences. Strings in particular are just sequences of codepoint atoms.

It had a notion of "type"s which were functions that returned a boolean 1 only if given a valid value for the type being defined. I presume it used byte packing and copy-on-write or whatever for its speed boasts.

https://openeuphoria.org/

https://rapideuphoria.com/

> In herd, everything is immutable unless declared with var

So basucally everything is var?