Category Archives: SAoC

SAOC 2021 Projects

Digital Mars D logo

The applications have been reviewed, the results decided, and the applicants notified. Five coders will be participating in the 2021 edition of the Symmetry Autumn of Code, one of whom will be the first to take part in SAOC two times.

Following is a brief introduction to each participant and an equally brief summary of their projects. The project planning phase officially kicks off on September 1st, so any details I could provide from their applications would likely change by the time they finalize their initial milestones with their mentors. If you’re eager for more detail, please hold out a little while longer. The participants will start posting updates in the forums once their projects are underway. Their first updates should include more information.

Rethinking the default class hierarchy

If you followed SAOC 2020, you may recall that Robert Aron was a fourth-year student at University POLITEHNICA of Bucharest who worked on implementing D client libraries for the Google APIs, along with a tool to generate client libraries for said APIs (all of which can be found in his GitHub repositories). He also was a recipient of the final SAOC payment (one of two last year, where usually we have only one) and is owed a free trip to a future real-world DConf.

Robert is now working toward an MSc in Security of Complex Networks at the same university, and he’s back with us for SAOC 2021. His project this time around is a DIP for and implementation of the ProtoObject concept that Eduard Staniloiu described in his DConf 2019 talk. This will set a ProtoObject class as the root class of D’s object hierarchy and the ancestor of the existing Object class. It will allow users to opt-in to features currently provided by default through Object, such as the inclusion of a monitor to support synchronization.

Once again, Robert will be working with Eduard Staniloiu and Razvan Nitu as his mentors.

Welcome back, Robert!

Replace DRuntime hooks with templates

Teodor Dutu is also at university in Bucharest working on a master’s degree in Advanced Cybersecurity. He has experience in C and Java, and it’s the low-level experience he gained working on projects like a file system, a kernel module, and an asynchronous HTTP server that he wants to apply toward improving the D ecosystem. The D language grabbed his interest when he participated in Razvan and Edi’s D Summer School, and he is eager to help out where he can.

To that end, Teodor is entering SAOC to work on a change to DRuntime. Currently, certain operations in user code are rewritten to call functions in the runtime known as runtime hooks (if you’ve ever seen a linker error mentioning something like _d_newArrayT or a symbol with a similar name, that was a runtime hook). There are some significant downsides to this approach, such as code bloat (the entire DRuntime library is linked in when linking statically), negative performance impact (due to the use of TypeInfo to pass runtime information to the hooks), and code that’s hard to maintain (the hooks are inserted at the IR level, a component of the compiler that’s difficult to understand).

Teodor’s plan is to replace each of the runtime hooks with templates. Dan Printzell already did some work on this, and Teodor will be following in his footsteps intending to take it all the way.

Eduard Staniloiu and Razvan Nitu will be Teodor’s mentors.

Implement support for D in LLVM Debugger (LLDB)

Luís Ferreira has extensive experience with C, C++, and D. He has contributed to DMD, DRuntime, and Phobos, and has a WIP implementation of DIP 1029 (Add throw as a Function Attribute) underway.

One of the projects Luís has been working on in his free time is a rewrite of DRuntime’s demangler to avoid exceptions, taken on because of his interest in mangling and demangling. He also has an interest in LLVM. The combination sparked the idea for his SAOC project. His rough goals for the project are to add support to LLDB for demangling D symbols, recognizing D-specific data structures, and parsing D expressions.

Mathias Lang has taken on the role of mentor for this project.

Light Weight DRuntime (LWDR)

Dylan Graham made waves on this blog when he wrote about the custom gearbox controller he built, using D for its firmware. That project led him to a new one: D needs a runtime that is suitable for embedded, Internet of Things, and real-time operating systems. That’s when he started work on LWDR.

You can see from that link that LWDR is not a port of DRuntime, but “a completely new implementation for low-resource environments”, and you’ll find a list of features that are currently supported. For SAOC, Dylan will be working on expanding feature support, shoring up what’s already there and adding new features along the way.

Dylan is a university student in Australia, currently pursuing a Bachelor of Computer Science through Monash University. He’s been programming since he was 11 years old, starting with C on the Arduino Uno and BASIC on the Maximite. His courses have exposed him to several other languages, and he has shown he’s a good hand with D.

His mentor for SAOC 2021 is Adam D. Ruppe.

Improve DUB: solve dependency hell

Ahmet Sait Koçak is a Computer Engineering student from Turkey. He has a strong background in C#, but considers D his second-most comfortable language. Some might be familiar with his work maintaining bindbc-harfbuzz.

For his SAOC project, he made use of our Projects repository and settled on the idea of solving the “dependency hell” problem that can arise when using DUB. Essentially, if library A depends on libraries B and C, which in turn depend on two different versions of library D, dub will error out without any effort to resolve the version conflict.

In reviewing the application, the judges identified some issues with the project as proposed, but it was still accepted with the understanding that Ahmet may need to take a different approach. His project subsequently gained the distinction of being the first SAOC project application discussed in a D Language Foundation meeting. The goal was to determine if there might be another way.

Ahmet’s mentor is Max Haughton, who was present for the meeting. He will be working with Ahmet to investigate the solution arrived at in the meeting and, if that proves infeasible, to move forward with the initial idea. Either way, you’ll hear the details from Ahmet in his weekly forum updates.


The SAOC judges (Átila Neves, Robert Schadek, and John Colvin) were impressed with the quality of the applications this year and are eager to see how the projects turn out. Please keep an eye out for the weekly updates that should start arriving in the forums around September 22nd, a week after Milestone 1 begins. This will help you keep abreast of the progress of each project and also provide an opportunity for suggestions that might help our SAOC 2021 coders along their paths.

Milestone 1 kicks off on September 15th, and Milestone 4 will end on January 15th. The D Language Foundation and our sponsors, Symmetry Investments, wish these five coders well in all they do over those four months. Their success is the D community’s success, so we hope everyone will join us in ensuring they have all the support and help they need to get through their four milestones and see this thing through to the end.

D News Roundup

Version 2.097.0 of DMD, the D programming language reference compiler, was released on June 5th in the middle of new GDC and LDC release announcements, while preparations for two major D community events were underway: the Symmetry Autumn of Code 2021 and DConf Online 2021. We’ll cover it all in this post, with a focus first on the events.

Symmetry Autumn of Code 2021

Symmetry Investments logo

As I write, Symmetry Investments employs in the neighborhood of 180 full-time workers and manages over US$8 billion of capital, and they’re always on the lookout for more employees, including programmers to work with D and other languages. They sponsored DConf 2019 in London and have sponsored the annual Symmetry Autumn of Code since 2018, in which a handful of programmers are paid to work for four months on projects of benefit to the D ecosystem.

This year marks the fourth annual SAoC, and we are now accepting applications. Participants will plan four milestones for projects that benefit the D ecosystem and will be expected to work at least 20 hours per week on each milestone. Each participant will be rewarded US$1000 for the successful completion of each of the first three milestones. At the end of the final milestone, the SAoC committee will review the overall progress of each of the remaining participants. One will be rewarded with a final $US1000 payment and a free pass to the next real-world DConf, with reimbursement for travel and lodging. In last year’s event, a second participant was also awarded a fourth US$1000 payment.

Participation in SAoC has led to jobs for some lucky coders and has generally been a valuable learning experience for those who have completed it. Students currently enrolled in graduate or postgraduate university programs will be given priority, but applications are open to all. The application deadline is August 18th. Project ideas can be found in the D community’s projects repository at GitHub. See the Symmetry Autumn of Code page here at the D Blog for all the details on how to apply as a participant or as a mentor.

DConf Online 2021

For the second consecutive year, we were unable to hold a real-world DConf. Last year we launched the first annual DConf Online. And when I say annual, I mean annual! We’re doing it again this year and will continue to do it going forward even after the real-world DConfs are back on.

DConf Online 2021 will take place November 20 and 21 on the D Language Foundation’s YouTube channel. Once again, we’re looking for pre-recorded talks, livestream panels, and livecoding sessions. If you’d like to propose something in one of those categories, the application deadline is September 5. Please visit the DConf Online 2021 homepage for all the details.

And if you haven’t seen them yet, the DConf Online 2020 and DConf Online 2020 Q & A playlists are available on the same channel. You can also find a full list of talks and all the links (talk videos, slides, and Q & A videos) on the DConf Online 2020 homepage.

New compiler releases

D 2.097.0 is live in the latest release of DMD and the beta release of LDC, the LLVM-based D compiler. The new version of GDC also came into the world as part of GCC 11.1 at the end of April.

DMD 2.097.0

Digital Mars D logo

This version of DMD comes with 29 major changes and 144(!) fixed Bugzilla issues courtesy of 54 contributors. Changes include a few deprecations and several improvements to the standard library. Two things stand out:

  • while(auto n = expression) has been on a few wishlists for a while. Now it’s a reality. The same syntax that was already possible with if statements is considered idiomatic in certain circumstances (such as when checking if an item exists in an associative array). Expect the while condition assignment to start popping up in open-source D projects soon.
  • std.sumtype is another wishlist item that is a wish no more. The new SumType is a replacement for std.variant.Algebraic. It’s a discriminated union that makes good use of Design by Introspection with a nice match syntax for those looking for that sort of thing. It’s been quite a while since the last time a new module was added to the D standard library. Many thanks to Paul Backus for putting in the effort to see it through, and a very big Congratulations!

LDC 1.27.0-beta1

LDC logo

On the same day the new DMD was released, the first beta of LDC 1.27.0, which also supports D 2.097.0, was announced in the D forums.

On top of 2.097.0 support, this version of LDC provides greatly improved DLL support on Windows. The prebuilt Windows packages ship with DRuntime and Phobos DLLs. This is big news for D developers on Windows. We’ve long had issues with D DLLs that have prevented heavy use outside of simple interfaces (with APIs exported as extern(C) being the most reliable).

There are some limitations to be aware of, such as the inability to directly access TLS variables across DLL boundaries (though it’s fine with accessor functions). Please see the release page for the details.

Thanks to Martin Kinkelin and all the LDC maintainers and contributors for their continued work on LDC. They aren’t getting paid for this. If you are a happy LDC user or just like the idea of the project, you can support their work by sponsoring Martin Kinkelin on GitHub.

GDC 11.1

In the GCC world, Iain Buclaw continues to make strides on the GDC compiler.

GDC 11.1 still uses the old C++ version of the D frontend, which feature-wise is mostly (see below) at D 2.076.1. There were significant issues in upstream DMD that prevented Iain from making the switch to the D version of the frontend in time to make the release window. He is currently aiming to make the switch in time for GDC 12. As a consolation, this release has support for three BSDs, Mac OS X, and MinGW!

Despite the older frontend, Iain has backported several fixes and optimizations, and even a few features, so it isn’t your grandfather’s D 2.076.1 that GDC supports. For example, the new bottom type that recently made its way through the D Improvement Proposal review process has found its way into this GDC release. See the forum announcement for details of all the new D goodness in GDC 11.1 and Please consider sponsoring his work on GitHub.

One-off donations

If you aren’t up for sponsoring Martin or Iain but would still like to support them financially, you can make one-time donations through the D Language Foundation. You can send money to the D General Fund, the D Open Collective, or to our PayPal account. Whichever method you choose, please be sure to leave a note that the donation is intended for LDC, GDC, or any D project you would like to support. We’ll make sure the appropriate person receives the money.

Other options for supporting the D programming language: visit the D Language Foundation donation page and donate to one of our funds, head to the DLang Swag Emporium and purchase any items that catch your eye (the D Rocket stuff rocks, and DConf Online 2021 swag will be available shortly), or consider using and selecting the D Language Foundation as your charity the next time you shop at (we are only available through the .com domain; browser extensions like SmartAmazonSmile for Firefox and AmazonSmileRedirect for Chrome make it easy to do).

Thanks to everyone who has, will, or continues to support the D programming language, either through donations of time or money. We’ve gotten where we are through community effort, and community effort will keep pushing us forward. D rocks!

Symmetry Autumn of Code 2020 Projects and Participants

Symmetry Investments logoThe verdict is in! Five programmers will be participating in the 2020 edition of the Symmetry Autumn of Code. Over the next three weeks, they will be working with their mentors to take the goals they outlined in their applications and turn them into concrete tasks across four milestones. Then, on September 15th, the first milestone gets under way.

Throughout the event, anyone can follow the progress of each project through the participants’ weekly updates in the General forum. Please don’t ignore those posts! You might be able to offer suggestions to help them along the way.

And now a little about the SAOC 2020 participants and their projects.

  • Robert Aron is a fourth-year Computer Science student at University POLITEHNICA of Bucharest. For his project, he’ll be implementing D client libraries for the Google APIs. When it’s complete, we’ll be able to interact with Google service APIs, such as GDrive, Calendar, Search, and GMail, directly from D. The goal is to complete the project by the end of the event.
  • Michael Boston is currently developing a game in D. For his SAOC project, he’ll be taking some custom data structures he’s developed and adapting them to be more generic. The ultimate goal is to get Michael’s modified implementation merged into Phobos. Should that not happen, the library will still be part of the D ecosystem once it’s complete.
  • Mihaela Chirea is a fourth-year Computer Engineering student at University POLITEHNICA of Bucharest. Mihaela will spend SAOC 2020 improving DMD as a library. Part of this project will involve soliciting community feedback regarding proposed changes, so anyone interested in using DMD as a library should keep an eye out for Mihaela’s posts in the D forums.
  • Teona Severin is a first-year master’s degree student at University POLITEHNICA of Bucharest who will be working on a mini DRuntime in order to bring D to low-performance microcontrollers based on ARM Cortex-M CPUs. Currently, D can run on such systems when compiled as -betterC, but the end goal of this project is to get enough of a functional DRuntime to write “a simple application that actively uses a class.“
  • Adela Vais is yet another fourth-year Computer Engineering student at University POLITEHNICA of Bucharest. For her project, she’ll be implementing a new D backend for GNU Bison. Currently, Bison has an experimental LALR1 parser for D. Adela’s implementation will be a GLR parser intended to overcome the limitations of the LALR1 parser.

The strong showing from Bucharest is down to the work of Razvan Nitzu and Eduard Staniloiu. They have introduced a number of students to the D programming language and encouraged them in seeking out projects beneficial both to their education and to the D community. Plus, Razvan and Edi will be participating in SAOC 2020 as mentors.

On behalf of the SAOC 2020 committee, the D Language Foundation, and Symmetry Investments, I want to thank everyone who submitted an application and wish the participants the best of luck in the coming months.

Deadlines and New Swag

SAOC 2020 Application Deadline

Symmetry Investments logoThe deadline for Symmetry Autumn of Code (SAOC) 2020 applications is on August 16th. There’s work to be done and money to be paid (courtesy of Symmetry Investments). If you know of a project that can keep an eager programmer busy for at least 20 hours a week over the course of four months, please advertise it in the forums and add it to the project ideas list if it isn’t already there.

As for potential applicants, remember that experience with D is not necessary. Experience with another language can be transferred to D “on the job”, with a mentor to guide the way. Tell your friends and spread the word to other programming communities. This is a great way to bring new faces to the D community and the new ideas they may bring with them. All the information on how to apply and how to become a mentor is available on the SAOC 2020 page.

DConf Online 2020 Swag

DConf Online 2020 Logo

The DConf Online 2020 submission deadline of August 31 will be here before we know it. If you haven’t put a submission together yet, head over to the DConf Online 2020 home page (and/or the announcement here on the blog) for the details on what we’re looking for and how to go about it. Everyone whose submission is accepted for the event schedule will receive a t-shirt and coffee mug to commemorate the occasion.

For everyone else, those t-shirts and mugs are on sale now at the DLang Swag Emporium along with tote bags and stickers. Remember, all of the money we raise through the store goes straight into the General Fund, which we’ll dip into to provide DConf Online 2020 speakers with their free stuff and a few lucky viewers with prizes. Donations made directly to the General Fund, or to any of our ongoing campaigns, are also greatly appreciated.

DConf Online 2020: Call For Submissions

DConf Online 2020 LogoDConf Online 2020 is happening November 21 & 22, 2020 in your local web browser! We are currently taking submissions for pre-recorded talks, livstreamed panels, and livecoding events. See the DConf Online 2020 web site for details on how you can participate. Keep reading here for more info on how it came together and what we hope to achieve, as well as for a reminder about the 2020 edition of the Symmetry Autumn of Code (the SAOC 2020 registration deadline is just over three weeks away!).

Maybe Next Time, London!

Due to the onset of COVID-19, the D Language Foundation and Symmetry Investments decided in early March to cancel DConf 2020, which had been scheduled to take place June 17–20 in London. DConf has been the premiere D programming language event every year since 2013, the one chance for members of the D community from around the world to gather face-to-face outside of their local meetups for four days of knowledge sharing and comradery. It was a painful decision, but the right one. As of now, we can’t say for sure there will be a DConf 2021, but it’s looking increasingly unlikely.

Immediately upon reaching the decision to cancel DConf, the obvious question arose of whether we should take the conference online. It was something none of the DConf organizers had any experience with, so we were unwilling to commit to anything until we could figure out a way to go about it that makes sense for our community. As time progressed and we explored our options, the idea became more attractive. Finally, we settled on an approach that we think will work for our community while still allowing outsiders to easily drop by to get a look at our favorite programming language.

We also decided that this is not going to be an online substitute for the real-world DConf. That’s why we’ve named it DConf Online 2020 and not DConf 2020 Online. We’re planning to make this an annual event. The real-world DConf will still take place in spring or summer (barring pandemics or other unforeseen circumstances), and DConf Online six months or so later. Without the DConf cancellation, we never would have reached this point, so for us that’s a bit of a bright side to these dark days.

DConf on YouTube

DConf Online will take place on the D Language Foundation’s YouTube Channel. The event will kick off with a pre-recorded keynote from Walter Bright, the creator and co-maintainer of D, on November 21, scheduled to premiere at a yet-to-be-determined time. Other pre-recorded talks will be scheduled to premiere throughout the weekend, including a Day Two keynote on November 22 from co-maintainer Átila Neves. Presenters from the pre-recorded talks will be available for livestreamed question and answer sessions just as they would be in the real-world DConf.

We’ll also be livestreaming an Ask Us Anything session, a DConf tradition, with Walter and Átila. We’re looking for other ideas for livestream panels. Anyone submitting a panel proposal should either be willing to moderate the panel or have already found someone to commit to the position.

And we really, really want to have at least two livecoding sessions. Anyone familiar with D who has experience livecoding is welcome to submit a proposal. Ideally, we’re looking for sessions that present a solid demonstration of D in use, preferably a small project designed exclusively for the livestream, something that can be developed from start to finish in no more than 90 minutes. We aren’t looking for tutorial style sessions that go into great detail on a feature or two (though that sort of thing is great for a pre-recorded talk submission!), but something that shows how a D program comes together and what D features look like in action.

Everything you need to know to submit a pre-recorded talk, panel, or livecoding session to the D Language Foundation can be found at the DConf Online 2020 web site. We’ll have more details here and on the web site in the coming weeks as our plans solidify. Oh, and everyone whose submission is accepted will receive some swag from the DLang Swag Emporium (DConf Online 2020 swag is coming soon).


It’s a DConf tradition that a gathering spot is selected where attendees can get together each evening for drinks, food, and conversation. For many attendees, this is a highlight of the conference. The opportunity to engage in conversation with so many smart, like-minded people is not one to be missed. Ethan Watson dubbed these evening soirees “BeerConf”, and the name has stuck.

Recently, Ethan and other D community members have been gathering for a monthly online #BeerConf. Given that it’s such an integral part of the DConf experience, we hope to make use of the lessons they’re learning to run a BeerConf in parallel to DConf Online, starting on the 20th. Despite the name, no one will be expected to drink alcohol of any kind. It’s all about getting together to socialize as close to face-to-face as we can get online.

More details regarding BeerConf will be announced closer to the conference dates, so keep an eye on the blog!

SAOC 2020

Symmetry Autumn of Code is an annual event where a handful of lucky programmers get paid to write some D code. Sponsored by Symmetry Investments, SAOC 2020 is the third edition of the event. Although priority is given to university students, SAOC is open to anyone over 18.

Applicants send a project proposal and a short bio to the D Language Foundation. Those who are selected will be required to work on their project at least 20 hours per week from September 15, 2020, until January 15, 2021. The event consists of four milestones. Participants who meet their goals for the first three milestones will each receive a payment of $1000. For the fourth milestone, the SAOC Committee will evaluate each participant’s progress for the entire event. On that basis, one will be selected to receive a final $1000 payment and a free trip to the next real-world DConf (no registration fee; travel and lodging expenses reimbursed on the same terms as offered to DConf speakers). The lucky participant will be asked to submit a proposal for the same DConf they attend, but their proposal will be evaluated in the same manner as all proposals (i.e., acceptance is not guaranteed), but they are guaranteed free registration and reimbursement regardless.

Although Roberto Romaninho, our SAOC 2019 selectee, was robbed of the opportunity to attend DConf 2020, he will still be eligible to make use of his reward at our next real-world event along with the 2020 selectee. Francesco Gallà, who was selected in the inaugural SAOC 2018, gave a presentation about his project and the SAOC experience at DConf 2019. The runner up, Franceso Mecca, wrote about his own project for the D Blog.

SAOC 2020 applications are open until August 16. See the SAOC 2020 page for all the details on how to apply.

SAOC 2020 and Other News

Symmetry Autumn of Code 2020

Symmetry Investments logo

The 3rd annual Symmetry Autumn of Code (SAoC) is on!

From now until August 16th, we’re accepting applications from motivated coders interested in getting paid to improve the D ecosystem. The SAoC committee will review all submissions and, based on the quality of the applications received, select a number of applicants to complete four milestones from September 15th to January 15th. Each participant will receive $1000 for the successful completion of each of the first three milestones, and one of them will receive an additional $1000 and a free trip (reimbursement for transportation and accommodation, and free registration) to the next real-world DConf (given the ongoing pandemic, we can’t yet be sure when that will be).

Anyone interested in programming D is welcome to apply, but preference will be given to those who can provide proof of enrollment in undergraduate or postgraduate university programs. For details on how to apply, see the SAoC 2020 page here at the D Blog.

The participants will need mentors, so we invite experienced D programmers interested in lending a hand to get in touch and to keep an eye out in the forums for any SAoC applicants in search of a mentor. As with the previous edition of SAoC, all mentors whose mentee completes the event will be guaranteed a one-time payment of $500 after the final milestone (mentors of unsuccessful mentees may still be eligible for the payment at the discretion of the SAoC committee). Potential mentors can follow the same link for details on their responsibilities and how to make themselves available.

We’re also looking for community input on potential SAoC projects. If there’s any work you’re aware of that needs doing in the D ecosystem and which may keep a lone coder occupied for 20 hours per week over four months, please let us know! Once again, details on how submit your suggestions and what sort of information we’re looking for can be found on the SAoC 2020 page.

Our SAoC 2019 selectee, Roberto Rosmaninho, was all set to attend DConf 2020 and we were all looking forward to meeting him. He’ll still be eligible to claim his free DConf trip at the next available opportunity.

SAoC would not be possible without the generosity of Symmetry Investments. A big thanks to them for once again funding this event and for the other ways, both financial and otherwise, they contribute back to the D programming language community.


Thanks to everyone who has shopped in the DLang Swag Emporium! To date, the D Language Foundation has received over $177 in royalties and referral fees. Thanks are also in order to those who have supported the foundation through Your purchases have brought over $288 into the General Fund. Amazon Smile is perhaps the easiest way to support D financially if you shop through Amazon’s .com domain (the D Language Foundation is unavailable in other Amazon domains). If you’ve never done so, you can select a charitable foundation (the D Language Foundation, of course) on your first visit to Then, every time you shop through that link, the foundation will receive a small percentage of your total purchase. Check your browser’s extension market for plugins that convert every link to a link!

On the Task Bounties front, we may have closed out a big bounty for bringing D to iOS and iPadOS, but there are still several other bounties waiting to be claimed. The latest, currently at $220, is a bounty to improve DLL support on Windows by closing two related Bugzilla issues; 50% of the total bounty will be paid for the successful closure (merged PR and DMD release) of each issue. We welcome anyone interested in fixing these issues to either up the bounty or roll up their sleeves and start working toward claiming it. If you’d like to contribute to multiple bounties with a single credit card payment, or seed one or more new bounties with a specific amount, visit the Task Bounty Catch-All and follow the instructions there.

Finally, the question was recently raised in the forums about how to view the D Language Foundation’s finances. Because the foundation is a 501(3)(c) non-profit public charity, the Form 990 that the organization is required to submit to the IRS every year is publicly available. There are different ways you can obtain the documents for multiple years, such as searching online databases or contacting the IRS directly. Several websites, such as, provide details on how to do so. The Form 990 does not break down specific expenditures or sources of income except for special circumstances (like scholarship payments). With Andrei’s help, I’m currently working on gathering up more information on the past five years of the foundation’s finances so that we can put up an overview page at It won’t be at line-item detail, but we hope to provide a little more detail than the Form 990. I can’t provide a timeline on when it will be available (I don’t consider it a high priority task, so I’m working on it sporadically), but expect it sometime in the next few months.

DConf Online?

Rumor has it that online conferences are actually a thing. Voices in the wind speak of the potential for an annual event related to D. I don’t usually listen to voices I hear in the wind, but this time I’m intrigued…

DConf 2020: Submission Deadline, Early-Bird Registration, and Invited Keynote

In early January, I announced that Symmetry Investments is bringing DConf back to London for our 2020 edition. At the same time, I said we’d start taking submissions from anyone who wanted to send them in. In the interim, we’ve fixed our deadlines and prepared to start accepting reservations. There was only one thing remaining before I was ready for the formal call for submissions and opening of early-bird registrations: confirming our invited keynote speaker. Now that he has confirmed, it’s all official!

Invited Keynote

We’re excited to welcome Roberto Ierusalimschy to DConf 2020! You may know him from his work as the leading architect of the Lua programming language. He’s the author of Programming in Lua and an Associate Professor of Computer Science at PUC-Rio (the Pontifical Catholic University of Rio de Janeiro).

We don’t know yet what his talk will about, but it can be about any topic he wants. We’ll have more information on that for you when we publish the schedule of all selected talks after April 19.

Call for Submissions

We are accepting submissions for DConf 2020 until April 12. Authors will be notified of their final status by April 19.

We’re eager to see some new faces on the stage this year. If you’ve never presented at a DConf before, please don’t hesitate to send us one or more submissions. One person has already sent in seven!

Unless you’re Roberto Ierusalimschy, we prefer topics that are directly or indirectly related to D. We aren’t intransigent, though, so we’re willing to consider other topics. If someone sends us a proposal that isn’t about D but piques our collective interest, we’ll certainly give it serious consideration.

Having a talk selected is a great way to get to DConf if you’re on a budget. You’ll pay no registration fee, plus we’ll reimburse your transportation and lodging costs (within reason—five-star hotels and business- or first-class plane tickets aren’t on the menu). That’s a pretty good deal.

You can find instructions for writing and submitting your submissions on the DConf 2020 homepage.

Early-Bird Registration

Early-bird registration is available at $340, which is 15% off the regular $400 rate. Because we’re being sponsored by Symmetry in London once more, we once again must include a 20% VAT. So the total early-bird rate is $408 (similarly, the regular rate with VAT will be $480). We’re required by UK law to show you the basic rate and VAT in GBP based on the current HMRC exchange rate. That changes every month, so you can see the latest GPB rates in the registration section of the DConf 2020 homepage.

There, you’ll find options for Flipcause and PayPal. From our perspective, we prefer you use our Flipcause form. That gives you the option to cover the credit card processing fee for us so that 100% of your payment can be put toward DConf expenses. If you choose to uncheck that option, that’s fine, too! It will still save us from paying other fees. Every penny we can put toward the expenses helps.

If you do choose to go through PayPal, you have an option for USD and one for GBP. Some registrants told me last year that they get a GBP option even when clicking the USD button. And of course, some register with GBP-based credit cards. However, the GBP button on the DConf 2020 homepage is a fixed amount based on the current HMRC exchange rate. It changes, but only once a month. It may turn out to be cheaper for you than the rate you get from PayPal or your credit card provider. Of course, it could turn out to be more expensive, so if you’re looking to save a few pounds, you may want to investigate the different exchange rates if they apply to your situation.

And Now For Something Completely Different

DConf isn’t the only event Symmetry Investments is sponsoring these days. We recently wrapped up the 2019 edition of the Symmetry Autumn of Code.

This year, we started with five participants working on five interesting projects. Each participant was to complete a total of four milestones over four months with guidance from a mentor. At the successful completion of the first three milestones, each participant would receive $1000. At the end of the fourth and final milestone, one participant would be selected to receive one more $1000 payment and an all-expense paid trip to DConf.

As the event played out, we lost one of the participants at the end of Milestone 2. Two more were unable to fully commit to the Milestone 4 deadline (though they promised to continue working on their projects after SAOC). That left two participants for the SAOC review committee to select from. It was a very difficult decision, as both participants did excellent work and received glowing evaluations from their mentors.

Now I can announce that the SAOC 2019 finalist was Roberto Rosmaninho!

Roberto, with his mentor Nicholas Wilson, worked on adding support for Multi-Level Intermediate Representation (MLIR) to LDC, the LLVM-based D compiler. He is currently working on putting together pull requests for LDC and intends to work on optimizations going forward. He has also confirmed that he will take advantage of his reward so that we will have at least two Robertos at DConf this year.

As we did last year with Francesco Gallà, the SAOC 2018 finalist, we’ve asked Roberto to submit a talk this year. He promised to do so. We can’t promise his talk will be selected (though the odds are high out of the gate), but he still gets a free trip if it isn’t! Besides, we’re looking forward to meeting him.

On behalf of the D Language Foundation and Symmetry Investments, I want to thank everyone who participated in SAOC 2019. Keep an eye on this blog for news about future events.

Now go prep your DConf 2020 submissions!

DMD 2.088.0 Released

Digital Mars logoThe newest DMD has rolled off the assembly line and is ready for download. A total of 58 contributors fixed 58 bugs and introduced 27 major changes to version 2.088.0 of the compiler.

I’m always looking for the big ticket items in a new DMD release to highlight on the blog, but this is a workaday release that isn’t showing off anything too shiny in the changleog. Much of it is run-of-the mill maintenance: deprecations, removals, and behavior adjustments. All of that is important, and we all welcome it, but it doesn’t make for great reading on the blog. That said, there are a handful of useful additions that I can point to, one of which actually is a big deal when it comes to C++ interop.

std::string and std::vector

Thanks to the work Manu Evans has been performing and advocating, C++ interoperability gets a big boost in this release with bindings to std::string and std::vector in the DRuntime modules core.stdcpp.string and core.stdcpp.vector, respectively.  There’s one caveat with the std::string binding that anyone intending to use it must be aware of.

When compiling on Linux, where DMD makes use of the GCC libraries and linker, there’s a compatibility issue when using the modern version of std::string which is compliant with C++11. It contains an interior pointer, which in D is both illegal and incompatible with move semantics. The work around is to pass -D_GLIBCXX_USE_CXX11_ABI=0 to g++ and compile your D application with -version=_GLIBCXX_USE_CXX98_ABI. This will be resolved in the future when work on move constructors in D is complete.

New Utilities

The language gets an interesting new compile-time trait in the form of getLocation. Given a symbol, this trait will return a tuple containing the file name, line number, and column number at which the symbol appears in the source code. This opens the door to more informative debug logging and error reporting beyond the functionality already available via __FILE__ and __LINE__. And I’m sure folks will find other uses for it.

The standard library utility module std.file, which provides a lot of convenience functions for working with files as a unit, now has the new function getAvailableDiskSpace. Give it a directory path on Windows, or the path to a directory or file on Posix, and it will give you the number of bytes available on that path.

Other News

The Symmetry Autumn of Code 2019 participants all have mentors now and they are hard at work laying out their milestones. Milestone 1 officially kicks off on September 15, after which we can expect to see weekly updates from the participants in the General forum.

Google Summer of Code 2019 has come to an end. Five of our students submitted their work at the end of August. You can find information about their projects and view their code submissions from our GSOC projects page. Congratulations to all who participated!

The D Language Foundation is currently in discussions to put some of the Human Resource Fund to use in finalizing LDC support for iOS and Android. Hopefully, I’ll have details to report on that front in the very near future. In the meantime, please help us raise the HR Fund even higher than it is now. There’s some important work waiting to be done that will require as much money as we can throw at it. You can donate any amount directly to the HR Fund Campaign or use the special campaign we set up to send $60 to the HR Fund and get a DConf 2019 t-shirt in return.

Speaking of t-shirts, thanks to everyone who has made a purchase in our DLang Swag Emporium. You’ve helped us raise over $77 so far, all of which will go to the General Fund. If you haven’t yet dropped in, what are you waiting for? We’ve got t-shirts, stickers, and coffee mugs, with updates coming soon. It’s an easy way to support our favorite programming language!


SAOC 2019 Projects and Participants

Symmetry Investments logoLast Sunday, August 18, was the deadline for Symmetry Autumn of Code 2019 applications. We received a total of eight applications, which is the same number we saw last year. This time around we were able to accept more than three: five of the applicants will be participating.

The applications were reviewed by the five members of the SAOC 2019 Committee. Each member independently ranked the applications in order of preference. Points were assigned based on the rankings and the top five applications were accepted.

Before we get into the details of the projects, on behalf of the D Language Foundation and the SAOC team, I’d like to publicly thank all eight applicants for taking the time to submit an application. I’d also like to thank Laeeth Isharc and Symmetry Investments for sponsoring the event again this year, and our five SAOC Committee members for volunteering their time throughout the event:  John Colvin, Mathias Lang, Átila Neves,  Robert Schadek, and Ethan Watson. They will be monitoring the progress of each project through the milestone reports and ultimately will select one participant to receive an extra $1000 payment and an all-expense paid trip to DConf 2020.

The Projects

  • Multi-Level Intermediate Representation Support for LDC – According to the MLIR project README, it’s “a common intermediate representation” intended to “unify the infrastructure required to execute high performance machine learning models in TensorFlow and similar ML frameworks”. Roberto Rosmaninho’s primary project goal is to provide the LDC D compiler with “a new level of abstraction to support the integration of MLIR into the D ecosystem”. Roberto is working on a Computer Science major and is an undergraduate research assistant at Federal University of Minas Gerais in Brazil. His mentor for the project is Nicholas Wilson.
  • Implement DIP 1014 and expand support for C++ STL containers – Suleyman Sahmi’s main goal is to “advance the existing work on [the] D interface to C++ STL containers”. There is a project at GitHub geared toward that end which Manu Evans and Laeeth Isharc have been working on and which is blocked on the lack of an implementation for DIP 1014, along with a few issues with the D ABI and name mangling. He first intends to implement DIP 1014, then he’ll resolve several of the related DMD bugs and will use the remaining time to expand support for the C++ STL. Suleyman is a self-taught programmer from Morocco and already has become a contributor to DMD.
  • DPP with Linux kernel headers – The DPP tool, which allows D modules to directly #include C and C++ headers, currently is unable to work with the Linux kernel headers. Cristian Becerescu aims to fix that. If he is able to do so with time remaining, he will work on further improvements and refinements to DPP, including ironing out issues it might have with other C library headers the community brings to his attention. Cristian is a 4th-year Computer Science and Engineering student at University Politehnica of Bucharest. He is fortunate to have two mentors for this project in the form of Edi Staniloiu and Razvan Nitu.
  • Create a CI or other infrastructure for measuring D’s progress and performance – Max Haughton, an 18-year-old British physics student, will be taking on the task of “creating a mechanism by which we can measure various properties of the D ecosystem in a deterministic manner”. This includes properties such as compilation time, compile-time memory usage, and profiling the compiler to determine “why performance is what it is”. He also intends to extend it to run-time performance by “forming a set of benchmarks by which we can profile Phobos and druntime both against their versions…and the version of the compiler”.
  • Solve Dependency Hell: link with more than one version of the same project – When a project has dependencies that in turn rely on different versions of the same library, steps must be taken to reconcile the version difference in order to successfully compile. If it’s even possible, it’s cumbersome and introduces new difficulties. Tiberiu Lepadatu aims to solve this problem of Dependency Hell by making it possible to compile a project with multiple versions of the same library. This is considered as a crucial first step in making Phobos available via the DUB registry. Tiberiu is no stranger to D and has contributed to the core projects in the past. He will likely be working with Sebastian Wilzbach as his mentor.

Getting Under Way

The SAOC participants will spend the next three weeks preparing to get their projects started. They’ll be compiling their Milestones, doing research, and those without a mentor will be searching for one. Things officially kick off on September 15, with Milestone deadlines falling on the 15th of each month through January.

This year, we’ll be expecting the participants to make weekly updates in the forums. We will also encourage them to spend time on IRC, Slack, or Discourse to get to know the community, discuss their projects, and find inspiration in solving the challenges they’ll face. We encourage all members of the D community to show their support and help keep up motivation.

Each of these projects will improve the D ecosystem.We’re fortunate to have this opportunity, along with out participation in the currently ongoing Google Summer of Code, to get so much done without the need to raise more money or dig into our Human Resource Fund. We should all be willing to do what we can to help these projects succeed.

On a personal level, I’m looking forward to working with these five programmers in the coming months and to seeing all of them make it through to the end of a successful Symmetry Autumn of Code!


Symmetry Autumn of Code Experience Report: Porting a fork-based GC

Symmetry Investments logoThe 2018 edition of the Symmetry Autumn of Code was a wonderful opportunity for me and two other students to dive into an interesting programming challenge and contribute to the D community. I am going to describe the process that led to my participation in SAOC and what this four months of work meant to me.

Who I am

I am an MSc student in Computer Science at the University of Turin in Italy. My interests mainly revolve around type systems, language theory, formal languages and compilers, and concurrent programming techniques. I am 23 years old and I have been programming since I was 20.

What happened before SAOC

While browsing Hacker News one day, one comment caught my attention: “the [D] community seems second to none as far as signal to noise ratio goes”. From that day I started lurking on the D forums and later read Andrei Alexandrescu’s book, The D Programming Language. While I think it alone wasn’t sufficient to learn the language, it was worth the read for all the discussions about compiler internals, the compromises about the syntax, and the details on ranges and concurrency by message passing.

After reading the book, I had enough confidence to start exploring some real-world code and I decided to dig into the codebases of the D standard library (Phobos) and vibe.d, a popular web app framework. My colleague Francesco Gallà, who also would participate in SAOC (see his DConf 2019 presentation about his experience), started learning D and we approached the community together by discussing one of the past Google Summer of Code proposals, HTTP2 support, on the vibe.d forum.

At the same time, I bought the Garbage Collection Handbook as a personal reading. At the time it seemed totally unrelated to what I was doing with D.


On July 14, 2018, the D Language Foundation announced the Symmetry Autumn of Code. It seemed the right occasion to boost my skills with D and get even more involved with the community. I was also thrilled by the possibility of learning new methodologies for writing code with a remote mentor.

I gathered information about a past project, a concurrent garbage collector that was used in D1 in the Tango library. I decided that my SAOC project proposal would be to port it to D2 with the goal of incorporating it into the D runtime.

The original work was done by Leandro Lucarella as his master thesis, and he documented it extensively on his blog. I contacted him and received confirmation that he could mentor such a project. After that, I wrote my proposal. It consisted of two documents, one about me and the other about the project.

The concurrent GC project

The project document had the objective of showing my efforts in understanding the garbage collector currently shipping with the D runtime—a conservative mark and sweep GC that does the following whenever an allocation is issued and memory needs to be reclaimed:

  1. stop all threads except the current one
  2. “hijack” the work of the current thread in order to run the GC routines
  3. start scanning recursively every root memory pointer in order to find every memory block that has been used or is being used by the program
  4. mark all GC-allocated blocks that are no longer referenced
  5. resume all other threads
  6. run destructors from unreachable memory that has been marked in phase 4 and free the remaining unreachable memory
  7. continue execution of the current thread.

The program is paused during steps 1 to 4 (the mark phase) and memory is reclaimed during step 6, where the GC thread hijacks the flow of the thread that triggered the collection. There are various approaches for reducing the pause time, such as using threads to scan and mark the memory objects in parallel; work is being done in that direction.

My proposal highlighted another strategy. By sacrificing memory consumption on systems that support Posix’s fork() system call, pause time could be drastically reduced. A fork-based concurrent GC would be represented by the following sequence of routines:

  1. a thread triggers the GC collection (such a thread is called the mutator)
  2. the GC clones the address space of the current program with the fork() system call
  3. while the parent process continues execution, the child process starts the mark phase
  4. at the end of the mark phase, before exiting, the child process communicates the marked bits (that can be reused) to the parent
  5. the GC uses the unmarked blocks for future allocations (lazy sweep).

With this schema, the pause time of the marking phase is reduced to the duration of the fork() call only. There are many advantages, such as the fact that the other threads do not need to be stopped and that the reclaim phase could run concurrently without hijacking the mutator. In particular, this strategy shows its strength in potentially long-running programs that have large heaps with a high number of live objects.

The implementation resulted in a bit more than 500 lines of code, given that the calling process (called the parent) generates a duplicate of itself in a different address space. This removes the need for synchronization, which has a high overhead both in terms of runtime performance and code implementation. Moreover, Unix and Linux systems provide very efficient fork() implementations with the use of COW memory.


The first thing that I did with Leandro was to correct the milestones that I had predicted. Based on his experience, we put a bigger focus on defining the tests rather than the programming. After that he specified the workflow to me. We setup a test suite in place, mainly composed of dustmite, the runtime benchmarks and tests, and some D1 programs that I ported.

After discussing and applying every change to the codebase in a different branch, I had to run the tests and then open a pull request on my GitHub repository asking for a review from Leandro. Commits had to be very granular and he always provided a lot of feedback. He was always prompt in replying and we had a number of exchanges by email before applying a change. Many times we discussed benchmarks and regressions, and sometimes I asked for help with debugging. I can confidently say that I spent more time researching, reading, debugging, and discussing code than I spent writing it.

I was alone in managing my time and my commitment. Leandro and the D Foundation were always present in discussing things by email, but they didn’t force any time sheet on me nor did they micromanage my work.

The end of SAOC

At the end of the four months of SAOC, I had a working implementation, but I decided to delay a pull request to the D runtime in order to work on some profiling code that could help developers understand in which cases the fork-based garbage collector brings advantages. After a precise garbage collector was announced for DMD 2.085.0, I decided to adapt my work to it. It was very straightforward given the clarity of the added code and the separation of concerns in place.

Leandro was available for mentoring even after SAOC. We exchanged many emails and he showed me how the D garbage collector is being profiled at Sociomantic.

The pull request

A pull request to the D runtime was my final milestone. I was ready at the beginning of February, but I started to procrastinate. I’d had no previous communication with any of the reviewers and I was timorous about engaging with them. I spent a lot of time refactoring my code back and forth and delaying my pull request. At a certain point, I even considered abandoning the final milestone and providing the GC as a library. In the meantime, Rainer Scheutze published a threaded implementation of the mark phase that reduced the mark time in the GC and I lost faith in my project.

Luckily for me, I had the opportunity to attend DConf 2019 in London. There I found many great people who talked with me and convinced to resume my work. I had a brief discussion with Rainer and I started testing against his implementation (I also found a related bug in the CPU detection code) and on the last day, during the annual Hackathon, I finally opened the pull request.

Since May 11, I have discussed changes to my code, reduced the number of lines of code, refactored and collapsed some functions, and resolved bugs related to program termination. The pull request is still open given that there were many rough edges, but overall I am very satisfied about the feedback received and with the whole process. Reviewers responded to every commit and provided guidance when needed. Whenever something wasn’t clear, I replied on GitHub or asked for help in the #D IRC on

In retrospect, I should have opened the PR much earlier and presented the reviewers with every doubt that I had along the path.

Experience analysis

SAOC helped me in understanding the dynamics behind contributing to a community project such as D. I was already spending a fixed amount of time reading the forum every day and I started to direct some of that effort to GitHub. Checking pull requests, commits, and issues was expensive work, but it was necessary to gain knowledge about the methodologies regarding the development of Phobos and the runtime.

I also learned that there are many changes that go unnoticed if you don’t closely follow the discussions on the PR queue. One example is Manu Evans’s work on core.stdcpp that is very difficult to follow when it’s scattered across different forum threads and lacks a proper announcement.

I think that overall, communication was a weak point of my experience. Regarding SAOC, we defined the work in detail but we didn’t put any effort on communicating the status of my work to the community. That could have triggered helpful suggestions from the community that could have helped me to discover holes in my implementation. Again, I benefited from this great amount of freedom in managing my work, but I think it could have coexisted with some effort on communicating more.

Finally, I had previously used D for higher level code, but SAOC forced me to discover D from a new angle; I dived into low-level code. I was amazed by the flexibility of the language and found myself becoming familiar with this different style of writing code very quickly.


The Symmetry Autumn of Code was a very rewarding experience. It was a period of discovery, self-growth, and involvement in a new community.

I am very grateful to Symmetry Investments and the D Language Foundation for this opportunity. Moreover, I want to thank my mentor, Leandro, for all of his help and for all the positive exchanges that we had.