It will be nice to write a Crystal program and when there is a need to squeeze more performance, to use call a Rust code from the Crystal program. In addition it will just be a fun way to learn both languages. Can someone share a step by step instructions for doing it? Google search sent me to this forum but it didn’t give me concrete steps I can follow. Thanks!

I believe it’s the same way you call C from Crystal. Read this: https://crystal-lang.org/reference/syntax_and_semantics/c_bindings/ And this: https://www.greyblake.com/blog/2017-08-10-exposing-rust-library-to-c/ (might be outdated, I don’t know where are the official Rust instructions for this) Essentially, Rust can provide an API like C does. Then you link your object from file from Crystal and that’s it.

[image] oren: when there is a need to squeeze more performance, to use call a Rust code from the Crystal program I’m confused. How do you expect to gain more performance from Rust? Rust and Crystal should be roughly on par performance wise. Both compile to a LLVM backend, so even the optimizations are pretty similar. There are some differences in the runtimes, but I’m not aware that makes a big difference. Many benchmarks show Rust and Crystal performing pretty similar. Even if one had a slight edge over the other, it would most likely not justify the overhead for switching to the other. This could still be a fun endevour, I just don’t think this makes sense when you’re looking for performance improvement.

[image] straight-shoota: I’m confused. How do you expect to gain more performance from Rust? Rust and Crystal should be roughly on par performance wise. Rust has a more mature and performant multi-threading environment than Crystal currently has, which could be leveraged.

Hello, Perfs are similar. I use FFI to be able to use some crates in Crystal, it allows to use Rust’s echo-system. If it helps, here’s a little POC in bulk. ├── Cargo.lock ├── Cargo.toml ├── Makefile ├── shard.yml ├── spec │ ├── myapp_spec.cr │ └── spec_helper.cr ├── src │ ├── lib.rs │ └── myapp.cr Makefile ifeq ($(shell uname),Darwin) EXT := dylib else EXT := so endif all: target/debug/myrust.$(EXT) LIBRARY_PATH=$(PWD)/target/debug:$(LIBRARY_PATH) crystal build src/myapp.cr -o myrust LD_LIBRARY_PATH=./target/debug ./myrust target/debug/myrust.$(EXT): src/lib.rs Cargo.toml cargo build cd src clean: rm -rf target myrust myrust.dwarf Cargo.tml [package] name = "crystal-rust" version = "0.1.0" [lib] name = "myrust" crate-type = ["dylib"] shard.yml name: myapp version: 0.1.0 authors: - Nicolas Talle targets: myapp: main: src/myapp.cr crystal: 0.32.1 license: MIT lib.rs #[no_mangle] pub extern "C" fn string() -> *const u8 { "Hello World\0".as_bytes().as_ptr() } myapp.cr @[Link("myrust")] lib R fun string() : UInt8* end module Myapp VERSION = "0.1.0" msg = String.new(R.string()) puts "from Rust #{msg}" end And to compile: make I use FFI (Rust) with the v0.34, but I have tested this POC only with Crystal v0.32. To go further, callbacks help well. Pay attention to who has the ownership of the variables.

I love stuff like this because it’s like “mad scientist” type stuff :laughing: I can’t wait to see what else you come up with this.

There is plenty reason to do this. For example, Rust can compile to WASM and Crystal cannot. Moreover. Rust has many blockchain SDKs whereas Crystal none. Yet Crystal can be used for a lot of the logic and interop. Rails has Helix to do this. Doing this with Crystal would be nice.

Crystal can generate WASM as it uses LLVM and WASM is one of LLVM targets

I thought there were still issues with this because Crystal was missing a few things to be able to do this? [image] Crystal in (possible) WASM everywhere future? It goes a little bit beyond that, but that’s generally the case. I’ve investigated porting Crystal to wasm32-wasi a few times over the last year and been able to get some simple programs compiling and running via various WASM runtimes. I’ve documented some of this here: GitHub - maxfierke/crystal-wasm-tools: Tools for compiling Crystal dependencies, bindings, etc. for use with wasm. I had to disable a lot of features within the stdlib to get anything working, so it’s very very rough, and not sup…

This is correct. Without the WASM ABI added to Crystal, there’s no WASM codegen support (plus allllll the other things outlined in the above post)

I know that garbage collection was a proposal on WASM a year or two ago; has that been officially included as part of the standard (/ is it available in the LLVM implementation)? It seems like that would be a major blocker (in addition to threads), and even then we’d probably need to write something to fit that standard (or use someone else’s implementation of WASM libgc).

Using Rust inside a Crystal program

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jzakiya April 18, 2020, 2:31pm 4

Rust has a more mature and performant multi-threading environment than Crystal currently has, which could be leveraged.

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Using Rust inside a Crystal program

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