Reddit Programming

https://www.reddit.com/r/programming/comments/1qi0soq/par_language_update_crazy_if_implicit_generics/

Thought I'd give you all an update on how the Par programming language (https://github.com/faiface/par-lang) is doing. Par is an experimental programming language built around linear types, duality, automatic concurrency, and a couple more innovations. I've posted a video called "Async without Await" (https://www.reddit.com/r/programming/comments/1p0goii/what_if_everything_was_async_but_nothing_needed/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) on this subreddit and you guys were pretty interested ;) Recently, we've achieved 3 major items on the Current Roadmap (https://github.com/faiface/par-lang/issues/127)! I'm very happy about them, and I really wonder what you think about their design. Conditions & if Read the full doc here. (https://faiface.github.io/par-lang/quality_of_life/if.html) Since the beginning, Par has had the either types, ie. "sum types", with the .case destruction. For boolean conditions, it would end up looking like this: condition.case { .true! => ... .false! => ... } That gets very verbose with complex conditions, so now we also have an if! if { condition1 => ... condition2 => ... condition3 => ... else => ... } Supports and, or, and not: if { condition1 or not condition2 => ... condition3 and condition4 => ... else => ... } But most importantly, it supports this is for matching either types inside conditions. if { result is .ok value => value, else => "", } And you can combine it seamlessly with other conditions: if { result is .ok value and value->String.Equals("") => "", result is .ok value => value, else => "", } Here's the crazy part: The bindings from is are available in all paths where they should. Even under not! if { not result is .ok value => "", else => value, // !!! } Do you see it? The value is bound in the first condition, but because of the not, it's available in the else. This is more useful than it sounds. Here's one big usecase. In process syntax (somewhat imperative), we have a special one-condition version of if that looks like this: if condition => { ... } ... It works very much like it would in any other language. Here's what I can do with not: if not result is .ok value => { console.print("Missing value.") exit! } // use `value` here Bind or early return! And if we wanna slap an additional condition, not a problem: if not result is .ok value or value->String.Equals("") => { console.print("Missing or empty value.") exit! } // use `value` here This is not much different from what you'd do in Java: if (result.isEmpty() || result.get().equals("")) { log("Missing or empty value."); return; } var value = result.get(); Except all well typed. Implicit generics Read the full doc here. (https://faiface.github.io/par-lang/types/implicit_generics.html) We've had explicit first-class generics for a long time, but of course, that can get annoyingly verbose. dec Reverse : [type a] [List] List ... let reversed = Reverse(type Int)(Int.Range(1, 10)) With the new implicit version (still first-class, System F style), it's much nicer: dec Reverse : [List] List ... let reversed = Reverse(Int.Range(1, 10)) Or even: let reversed = Int.Range(1, 10)->Reverse Much better. It has its limitations, read the full docs to find out. New Runtime As you may or may not know, Par's runtime is based on interaction networks, just like HVM, Bend, or Vine. However, unlike those languages, Par supports powerful concurrent I/O, and is focused on expressivity and concurrency via linear logic instead of maximum performance. However, recently we've been able to pull off a new runtime, that's 2-3x faster than the previous one. It still has a long way to go in terms of performance (and we even known how), but it's already a big step forward.  submitted by /u/faiface (https://www.reddit.com/user/faiface)

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