Use C inside Clojure, then run it on the JVM or compile a native binary.

• One source to rule them all — write code once, run it on both jvm and native binary

(ns clobits.examples.ncurses.hello-world
  (:require [clobits.native-interop :refer [*native-image*]]
            [clobits.c :as c])
  (:gen-class))

(if *native-image*
  (do (println "In native image context")
      (require '[clobits.ncurses.ni :as ncurses]))
  (do (println "In polyglot context")
      (require '[clobits.ncurses.poly :as ncurses])))

(defn -main [& args]
  (let [w (ncurses/initscr)]
    
    (ncurses/printw (c/str* "hello"))
    (ncurses/curs-set 0)
    (ncurses/refresh)
    (Thread/sleep 1000)
    
    (ncurses/endwin)))

For a bigger example, check out wasd_rect.clj

• Parse C function prototypes to Clojure maps
• Generate .h/.c-files and Clojure namespaces based off of C function prototypes or using Clojure maps
• Generate wrapper classes for easier use of c functions / structs in clojure

This project is a work in progress. I wanted to share this mostly to add another example of how to use Clojure + C using GraalVM.

I'd be very happy if you tried to use it and have questions. If you have a specific C library you want to get working, let me know. Since the generated code can be reused, it'd be nice if we could host the bits required for various C libraries at clojars. :)

• Calling variadic C functions that do not have a va_args variation (see printf vs vprintf)

If you know how to solve the problems above, please tell me how! :) Either through an issue, or @Saikyun on twitter.

• graalvm -- tested with graalvm-ce-java11-20.2.0-dev: https://github.com/graalvm/graalvm-ce-dev-builds/releases
  • download, then add the following to e.g. .zprofile
  • export GRAALVM_HOME="/path/to/graalvm-ce-java11-20.2.0-dev/Contents/Home/"
• install native-image: $GRAALVM_HOME/bin/gu install native-image (will be installed by ./compile otherwise)
• install llvm toolchain: $GRAALVM_HOME/bin/gu install llvm-toolchain
• leiningen -- https://leiningen.org/

Tested on macos and linux.

git clone https://github.com/Saikyun/clobits
cd clobits

Displays hello for a second.

make ncurses-poly

make clean ncurses-ni

Displays hello for a second.

make bounce-poly

make bounce-ni

You need libSDL2 on your path, and possibly added to "-Djava.library.path=<LIB_PATH_HERE>" under your OS profile in project.clj. I've put some defaults there, but I'm not sure they're universal.

make sdl-poly

make sdl-ni

You should see a red square, that you can control with wasd

The examples contain source code and more information about the examples.

If you start one of the examples in polyglot-mode you can connect to it using a repl. I usually go with a socket repl on port 5555, which is automatically started when you use the makefile.

• sogaiu -- support, testing and helpful discussion
• cornerwings -- java + native image example: https://github.com/cornerwings/graal-native-interaction
• u/duhace -- java + polyglot example: https://www.reddit.com/r/java/comments/8s7sr8/interacting_with_c_using_graalvm/
• borkdude -- help, project setup for clojure / native image compilation: https://github.com/borkdude/clj-kondo

Copyright © 2020 Jona Ekenberg

Distributed under the EPL License. See LICENSE.

This project contains code from:

• Clojure, which is licensed under the same EPL License.
• clj-kondo, which is licensed under the same EPL License.