alt Hacker News(Edit: in the old post title:) "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. (1) The atom: a possibly floating point number, and (2) 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.
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> 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've got a hobby language that combines this with compile time code execution to get static typing - or I should say that's the plan, it's really just a tokenizer and half of a parser at the moment - I should get back to it.
The cool side effect of this is that properly validating dynamic values at runtime is just as ergonomic as casting - you just call the type function on the value at runtime.
Thanks, I updated the post title based on this and another comment. Thanks for the pointer to Euphoria too, looks like an interesting language with a lot of similar ideas.