Macro hygiene is the concept of macros that work in all contexts; they don't affect and aren't affected by anything around them. Ideally all macros would be fully hygienic, but there are lots of pitfalls and traps that make it all too easy to accidentally write unhygienic macros. This guide attempts to provide a comprehensive resource for writing the most hygienic macros.
First, a little aside on the details of Rust's module system, and specifically paths; it is
| #lang racket | |
| (require syntax/parse/define "foods.rkt" (for-syntax "foods.rkt")) | |
| (add-delicious-food! "pineapple") | |
| (add-delicious-food! "sushi") | |
| (add-delicious-food! "cheesecake") | |
| (define-simple-macro (add-food-combinations! [fst:string ...] | |
| [snd:string ...]) | |
| #:do [(for* ([fst-str (in-list (syntax->datum #'[fst ...]))] |
Here's a list of mildly interesting things about the C language that I learned mostly by consuming Clang's ASTs. Although surprises are getting sparser, I might continue to update this document over time.
There are many more mildly interesting features of C++, but the language is literally known for being weird, whereas C is usually considered smaller and simpler, so this is (almost) only about C.
struct foo {
struct bar {
int x;
If you're looking to write fast code in Rust, good news! Rust makes it really easy to write really fast code. The focus on zero-cost abstractions, the lack of implicit boxing and the lifetime system that means memory is managed statically means that even naïve code is often faster than the equivalent in most other languages out there, and certainly faster than naïve code in any equivalently-safe language. Maybe, though, like most programmers you've spent your whole programming career safely insulated from having to think about any of this, and now you want to dig a little deeper and find out the real reason that
| # output binary | |
| BIN := test | |
| # source files | |
| SRCS := \ | |
| test.cpp | |
| # files included in the tarball generated by 'make dist' (e.g. add LICENSE file) | |
| DISTFILES := $(BIN) |
If you need a small makefile introduction/reference you can take a look at my notes https://www.mauriciopoppe.com/notes/os/bin/make/
Project structure
. project
├── Makefile
├── build
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |