Merge pull request #480 from mark-i-m/master

Add inside rust blog about WG-learning

Author: nikomatsakis

posts/inside-rust/2019-12-20-wg-learning-update.md

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+---
+layout: post
+title: "An Update from WG-Learning"
+author: mark-i-m
+team: the Learning Working Group <https://www.rust-lang.org/governance/teams/compiler#wg-learning>
+---
+
+# An update from WG-Learning
+
+In our last post in [October][oct] we gave an overview what the Learning WG is
+and what we are doing. We have made a lot of progress since that post, and we
+have also held a meeting to decide what to work on next. So let's dig in...
+
+## Work completed
+
+We mentioned before that we are in the process of producing [rustc-guide][rg]
+chapters from the "Compiler Lecture Series" videos. The goal is to try to
+produce guide chapters that are approachable for beginners and give a good
+foundation for exploring and hacking on the compiler.
+
+Recently, we merge a [chapter][salsach] on [`salsa`][salsa] by `@Karrq`.
+`salsa` is a crate that makes incremental computation easier. While it is not
+used in `rustc` itself, it is heavily inspired by it, and it is used by
+[`rust-analyzer`][ra].
+
+We also collectively have been working on a chapter about [`ty::Ty`][ty] and
+the way that rustc represents types internally. You can find that PR
+[here][typr]. This has been a big effort for a few months now, and we are excited
+to have this new chapter in the guide.
+
+## What's next?
+
+We just had a [planning meeting][meeting] to discuss what to work on next. The
+guide has some long-standing holes and shortcomings that we would like to address.
+
+Specifically, the Learning WG decided that we wanted to pursue the following goals next:
+- Write an overview chapter
+- Gather source material for chapters on monomorphization and LLVM
+
+### Overview chapter
+
+One of the challenges with big software systems is understanding how everything
+fits together. We have seen this problem come up with the rustc-guide; the chapters
+tunnel down into a single part of the compiler, but it is hard to get a good
+view of all the things that happen to a piece of code between lexing and linking.
+
+We want to remedy this problem by creating an Overview chapter that walks
+through some example from the beginning of the compiler to the end of the
+compiler at a high level.  We plan to put this chapter at the beginning of
+(part 2 of) the guide, so that it guide readers as to what part of the
+compilation they are reading about in the subsequent chapters.
+
+### Monomorphization, Codegen, LLVM
+
+One of the biggest gaps in the guide currently is what happens to your code
+after the MIR is produced. We have chapters on almost everything that happens
+before that (though many of them are pretty slim), but we have almost nothing
+after the MIR is produced, borrow checked, and optimized.
+
+In particular, after the MIR is optimized, we need to [monomorphize][glos] it,
+produce LLVM IR from it, call LLVM to produce executable code, and then link
+everything to form a final binary object.
+
+The Learning WG will work on collecting information to write chapters on these
+topics.
+
+## Getting involved
+
+Did any of this sound interesting to you? We would love for you to join us! You
+can the Learning WG on the [`t-compiler/wg-learning`][zulip] stream on Zulip.
+Feel free to stop by and ping us.
+
+
+[oct]: https://blog.rust-lang.org/inside-rust/2019/10/28/rustc-learning-working-group-introduction.html
+[rg]: https://rust-lang.github.io/rustc-guide/
+[salsa]: https://crates.io/crates/salsa
+[salsach]: https://rust-lang.github.io/rustc-guide/salsa.html
+[ra]: https://github.com/rust-analyzer/rust-analyzer
+[ty]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc/ty/type.Ty.html
+[typr]: https://github.com/rust-lang/rustc-guide/pull/530
+[meeting]: https://rust-lang.zulipchat.com/#narrow/stream/196385-t-compiler.2Fwg-learning/topic/planning.20meeting
+[glos]: https://rust-lang.github.io/rustc-guide/appendix/glossary.html
+[zulip]: https://rust-lang.zulipchat.com/#narrow/stream/196385-t-compiler.2Fwg-learning