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.

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doug-moen 4 hours ago | parent | next [-]

I am unable to extract any meaning from your post. You appear to be making a general claim: it is impossible to design a programming language where everything is a value. You at least admit that "data thingies" can be values. Are you claiming that it is not possible for functions to be values? (If we assume that the argument and the result of a function call is a value, then this would mean higher order functions are impossible, for example.) If not that, then what? Please give a specific example of something that can never be a value in any programming language that I care to design.

	▲	gf000 3 hours ago \| parent [-]
		I think parent means it from a lambda calculus perspective. If you only have values at an AST level, then you only have a tree of.. values, like an XML document. You can apply meaning to a particular shape of that tree which could be executed, but then you basically just added another layer before you parse your AST that becomes executable.

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bayesnet 2 hours ago | parent | prev | next [-]

IMHO this is both unnecessarily pedantic and not really quite right. Let’s say we accept the premise that “everything is a value” means reduction is impossible. But a value is just the result of reducing a term until it is irreducible (a normal form). So if there is no reduction there can’t really be values either—there is just “prose” (syntax) and you might as well read a book.

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jcparkyn 5 hours ago | parent | prev [-]

Thanks, some interesting reading there that I will check out (I wasn't aware of PCF). Perhaps I should've used more precise wording: "All types are value types".

> Standard ML [...] It has all you dream of and more

The main thing here that's missing in Standard ML (and most other functional languages) is the "mutable" part of "mutable value semantics" - i.e., the ability to modify variables in-place (even nested parts of complex structures) without affecting copies. This is different from "shadowing" a binding with a different value, since it works in loops etc.