[swift-dev] Implementing New Syntax in Swift

Svein Halvor Halvorsen svein.h at lvor.halvorsen.cc
Mon Jan 18 10:55:16 CST 2016

Can't you just make your SuperInt conform to IntergerLiteralConvertible and
initialise it like so:

let superIntExample: SuperInt = 100


2016-01-18 1:13 GMT+01:00 Seth Friedman via swift-dev <swift-dev at swift.org>:

> Created SR-569 <https://bugs.swift.org/browse/SR-569> to track this
> Thanks!
> Seth
> On Sun, Jan 10, 2016 at 4:18 PM, Seth Friedman <sethfri at gmail.com> wrote:
>> Changing the subject of this thread since it's now an entirely different
>> question than what I originally asked. Hopefully this will result in better
>> visibility in getting an answer as well.
>> Thanks,
>> Seth
>> On Sun, Jan 10, 2016 at 4:16 PM Seth Friedman <sethfri at gmail.com> wrote:
>>> Thanks Jordan!
>>> Here's a specific flow I'm interested in understanding. Note that this
>>> is just a wild example that would help me better understand parts of the
>>> compiler I'm interested in rather than any sort of proposal for the
>>> language.
>>> Let's say I have a type called SuperInt that has some cool integer
>>> operations that would be applicable and useful to everyone writing Swift.
>>> It's a given that this makes sense to be in the Swift language, and people
>>> are going to be using it so often that it makes sense to create a new
>>> literal syntax for this type. I'd like users to be able to instantiate a
>>> SuperInt with the following:
>>> let superIntExample = %^100^%
>>> Crazy syntax for a crazy example, but I wanted to make sure it's not
>>> something that's already in Swift. In this example, my SuperInt would be
>>> instantiated with a value of 100.
>>> I'd like to know the parts of the Swift compiler I would need to
>>> understand and change to implement this new type with its new syntax.
>>> I really this question requires a lengthy answer, but I think it would
>>> make a great start to a Swift internals manual (which I agree with you
>>> would be a fantastic idea).
>>> Anyone's help would be much appreciated!
>>> Thanks,
>>> Seth
>>> On Fri, Dec 18, 2015 at 5:25 PM Jordan Rose <jordan_rose at apple.com>
>>> wrote:
>>>> Hi, Seth. Sorry for not getting back to you sooner! I don't think we
>>>> have anything exactly like this, but there's *sort* of a sequence
>>>> diagram in Chris and Joe's talk at the LLVM conference, "Swift's
>>>> High-Level IR <https://youtu.be/Ntj8ab-5cvE>". I'd say it looks
>>>> something like this:
>>>> 1. Parsing
>>>> 2. Semantic analysis, including type-checking
>>>> 3. SIL generation
>>>> 4. Mandatory SIL passes
>>>> 5. SIL optimization
>>>> 6. LLVM IR generation
>>>> 7. LLVM optimization
>>>> 8. LLVM output (usually including machine code generation and writing
>>>> to a .o file)
>>>> …with the last two handled pretty much completely by LLVM
>>>> <http://llvm.org> itself, and not customized by Swift.
>>>> We probably ought to have something like Clang's "Internals
>>>> <http://clang.llvm.org/docs/InternalsManual.html>" manual (hopefully
>>>> better), which lays out the major concepts in each library. As it is we
>>>> have various concepts that are documented very well, either in docs/ or in
>>>> header comments, and others which are just arcane knowledge in the heads of
>>>> the implementers. This is not a good thing.
>>>> The "Contributing <https://swift.org/contributing/>" page on the
>>>> website lists a handful of ways to get involved; another one we're still
>>>> bringing up is issues with the "StarterBug" label in JIRA. These are
>>>> intended to be bugs that a newcomer could use as a goal-oriented way to
>>>> learn about one part of the project.
>>>> Of course, we're happy to answer any specific questions you might have
>>>> (and this list is probably the right place for them). It's the general ones
>>>> that are hard. :-)
>>>> Jordan
>>>> On Dec 16, 2015, at 2:36, Seth Friedman <sethfri at gmail.com> wrote:
>>>> Thanks Jordan!
>>>> Another question if anyone has some time: I'm really interested in
>>>> contributing to the project, but given that I don't have a ton of
>>>> experience with compilers, I'm having a really hard time following the flow
>>>> of the program. I understand that the high level flow is lexing, parsing,
>>>> sema, and building the AST. However, tracing through the actual functions
>>>> in the compiler prove much more difficult due to the amount of
>>>> indirection/metaprogramming.
>>>> Are there any sort of sequence diagrams that I haven't found yet? If
>>>> anyone could let me know of any good resources you know of, that would be
>>>> great. I'm sure this would also be of use to people in my boat that want to
>>>> help but don't know how to start.
>>>> Thanks,
>>>> Seth
>>>> On Tue, Dec 8, 2015 at 9:04 PM Jordan Rose <jordan_rose at apple.com>
>>>> wrote:
>>>>> Hi, Seth. I think you're getting Clang / swift-clang mixed up with
>>>>> swiftc / swift. Clang is not the Swift compiler; the Swift compiler lives
>>>>> in the "swift" repo. Swift depends on Clang for its interoperation with C
>>>>> and Objective-C.
>>>>> A *lot* of the compiler encodes information about Optional, but most
>>>>> of it stems from ASTContext.h and ASTContext.cpp, which has dedicated
>>>>> entrypoints for getting Optional, Optional.None, and Optional.Some.
>>>>> Hope this helps,
>>>>> Jordan
>>>>> On Dec 8, 2015, at 17:59 , Seth Friedman via swift-dev <
>>>>> swift-dev at swift.org> wrote:
>>>>> Hi all,
>>>>> In Optional.swift in the stdlib, there's a comment that says "The
>>>>> compiler has special knowledge of Optional<Wrapped>, including the fact
>>>>> that it is an enum with cases named 'None' and 'Some'."
>>>>> What I'm trying to understand is: If I wanted to implement the
>>>>> optional type from scratch, what would be the process I would go through?
>>>>> I've scoured the swift-clang project and can't seem to find any reference
>>>>> to optionals or even Swift explicitly. I discovered nullability attributes
>>>>> and am hypothesizing that an expression of something like "Type?" is
>>>>> somehow mapped to an attribute, but I'm really just stumbling around in the
>>>>> dark.
>>>>> In terms of what I've tried, I've gone through a lot of the source in
>>>>> the swift-clang lib/Basic and lib/AST directories, and I've read through
>>>>> the "Clang CFE Internals Manual" on the Clang website.
>>>>> Help is much appreciated!
>>>>> Thanks in advance,
>>>>> Seth
>>>>> _______________________________________________
>>>>> swift-dev mailing list
>>>>> swift-dev at swift.org
>>>>> https://lists.swift.org/mailman/listinfo/swift-dev
> --
> Seth Friedman
> *Software Development Engineer II*
> *Amazon.com*
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