The haskell source has `let channel = "11"` vs `let channel = 11`. The example from the post is an example that looks like it should be pretty straight forward but the swift compiler falls over when you try it.
Trying it locally for example:
# Original example
$ time swiftc -typecheck - <<-HERE
let address = "127.0.0.1"
let username = "steve"
let password = "1234"
let channel = 11
let url = "http://" + username
+ ":" + password
+ "@" + address
+ "/api/" + channel
+ "/picture"
print(url)
HERE
<stdin>:6:5: error: the compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions
4 | let channel = 11
5 |
6 | let url = "http://" + username
| `- error: the compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions
7 | + ":" + password
8 | + "@" + address
swiftc -typecheck - <<<'' 36.38s user 1.40s system 96% cpu 39.154 total
# Adding a type to one of the expression values
$ time swiftc -typecheck - <<-HERE
let address = "127.0.0.1"
let username = "steve"
let password = "1234"
let channel = 11
let url = "http://" + username
+ ":" + password
+ "@" + address
+ "/api/" + String(channel)
+ "/picture"
print(url)
HERE
swiftc -typecheck - <<<'' 0.11s user 0.03s system 74% cpu 0.192 total
Which is roughly the in line with the numbers in the original post.
The type is an inferred integer literal in swift (in the swift standard this is the `ExpressibleByIntegerLiteral`, the string literals are `ExpressibleByStringLiteral` types).
The reason this causes issues with the type checker is it has to consider all the possible combinations of the `+` operator against all the possible types that can be represented by an inferred integer literal.
This is whats causing the type checker to try every possible combination of types implementing the `+` operator, types implementing `ExpressibleByIntegerLiteral` and `ExpressibleByStringLiteral` in the standard library. That combination produces 59k+ permutations without even looking at non-standard library types.
If any of the types in the expression had an explicit type then it would be type checked basically instantly. Its the fact that none of the values in the expression have explicit types that is causing the type checker to consider so many different combinations.
> It doesn't break ARC right, it just won't do the automatic reference counting in C++ source. You can send it back and forth over the wall with CFBridgingRetain and CFBridgingRelease no?
I guess I should say that clang's ARC doesn't apply to these c++ wrappers.
The c++ code is loading symbols using the objc runtime API's to load symbols and call objc runtime APIs to dispatch the metal calls. So, you could pass these references to other objc code and it should have the correct refcounts afterwards.
Having to manually retain/release objects is a bit of a pain, but its workable.
Using a c++ RAII type to retain/release is also somewhat do-able, but I worked in a codebase that had that kind of code and it can be frustrating to get the refcounts to be correct synchronized. Although that was back with c++11, so I'm sure things have changed that would make this easier today.
If the object is not autoreleased then doing a release call will deallocate the object, otherwise it will be added to the nearest autorelease pool from the current stack and be deallocated when the pool is drained.
Swift and obj-c have the same ARC semantics, so I'm not sure what you mean by swift-style refcounting. It should be identical to the obj-c ARC semantics.
The c++ wrappings break ARC, so if you use this library you'll have to manually retain/release any object. The autorelease pool is helpful if you autorelease an object but you'll need to manually manage the memory when using this set of helpers.
In obj-c or swift, ARC would handle that for you, so this makes the memory management aspect of using Metal a bit more of a headache.
They went with a subset of C, its enough to write a working executable. Generally for a introduction tutorial to something as complex as writing a compiler a subset like what they presented in the article is enough to show how all the pieces work together to produce a working compiler.
TF can inline, but if it runs that optimization then the benchmark would be turned into a constant, so it wouldn't be measuring the call overhead of the way arguments are passed.
That's like how Catalysts runtime wasn't backported to older versions of macOS.
They could decouple those frameworks from the OS, but that adds other headaches and you eventually gotta draw the line somewhere so they tend to only add new frameworks with major OS updates.
It has a runtime API that should work with different versions of the OS. There were changes to the compiler that they didn't talk about until after the fact though. After SwiftUI was announced they did run those through swift-evolution.
SwiftUI for the most part is just a runtime library, the compiler changes made things a bit nicer, but most of it could be achieved without compiler changes.
Trying it locally for example:
Which is roughly the in line with the numbers in the original post.