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by massung
2439 days ago
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> For example, it turns out to be really convenient that strings are simply lists of characters. Statements such as these are very academic and concerning - to me - when it comes to new languages. And they make me wary of whether or not the language will ever move out of the land of theory and into practice. Continuing with the "strings are cons lists" theme... Other, very notable languages have tried this in the past: Erlang and Haskell immediately come to mind. And - without exception - they all end up regretting that decision once the language begins being used for real-world applications that require even a moderate level of performance. Lisp programmers (among which I count myself) are very fond of pointing to new languages and identifying all their "features" that were implemented in Lisp decades ago (so not "new"). And they also bemoan when a language design doesn't take a moment to learn from the mistakes of those that came before them. Strings as lists is very much in the latter case. The above said, the idea of streams as a fundamental type of the language (as opposed to a base class, type class, or what-have-you) is quite intriguing. Here's hoping they are more than just byte streams. |
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The reality of 2019 is that strings are not random access objects -- they are either empty or composed of the first char and the rest of the chars. A list is the proper primary abstraction for strings.
That is, if "list" is not a data structure but a mathematical concept -- based on the concept of "pair." If I were a Clojure or Swift programmer -- and I'm both, I'd say there are protocols that embody Listness and Pairness, and an implementation would have multiple dispatch that allows an object to deliver on the properties of those protocols. There are other fundamental concepts, though, that deserve inclusion in a language.
Is something suitable as the first argument of `apply`? Functions obviously are, but to Clojure programmers, hash tables and arrays are (and continuations are to Schemers) just as function or relation-like as a procedure. This is so obviously a good idea to me that I am irritated when a language doesn't support the use of random-access or dictionary-like collections as function-like objects.
Which brings us to random-access and dictionary-like objects. Those should have protocols. And given that sets are 1) not relations and 2) are incredibly important, set-like and perhaps bag-like itself deserve support.
At minimum, a designer should think through the protocols they want to support in a deep way and integrate those into the language. Maximally, protocols would be first-class features of a language, which is what I'd prefer, because a protocol-driven design is so often so much more productive than an OO one.
PG's plans with respect to all of the above are what really interest me. IIRC Arc embodied some of these concepts (arrays-as-functions), so at the moment I'm content to watch him climb this ladder that he's building as he goes and see what comes of it.
[Edit: various typos and grammatical errors.]