Clojure Hosted on Go

Gopher image derived from @egonelbre, licensed under Creative Commons 1.0 Attributions license. Glojure is an interpreter for Clojure, hosted on Go. Glojure provides easy access to Go libraries, similar to how Clojure provides easy access to Java frameworks. Glojure is in early development; expect bugs, missing features, and limited performance. Backwards compatibility is not guaranteed until a v1 release. That said, it is used successfully in hobby projects and runs a significant subset of the (transformed) core Clojure library. Note that unlike most other Go implementations of Clojure, Glojure is a "hosted" language - a term used to describe languages that are implemented in terms of a host language (in this case, Go). This means that all Go values can be used as Glojure values and vice versa. Before you get started with Glojure, make sure you have installed and have knowledge of Go (version 1.19 or higher). Glojure is currently available from source for all platforms where Go can run, and it requires at least go 1.24. Install it with the go install command: $ go install github.com/glojurelang/glojure/cmd/glj@latest After installation, you can start the REPL (Read-Eval-Print-Loop) with the glj command: $ glj user=> (println "Hello, world!") Hello, world! nil user=> Glojure can be used in two ways: as a standalone command-line tool (glj ) or embedded within Go applications. The glj command provides a traditional Clojure development experience: Show the help: $ glj --help # or glj -h Show the version: $ glj --version glojure v0.3.0 Start a REPL (interactive session): user=> *glojure-version* {:major 0, :minor 3, :incremental 0, :qualifier nil} $ glj user=> (+ 1 2 3) 6 user=> (println "Hello from Glojure!") Hello from Glojure! nil The interactive REPL includes: - Vi and emacs editing modes -- vi is the default; configure via ~/.inputrc - Multiline editing -- incomplete expressions continue on the next line with auto-indent - Tab completion -- symbols, namespaces, and aliases with descriptive labels - Smart indentation -- Tab inserts 2 spaces; Backspace removes a full indent level - Persistent history -- saved to ~/.glj_history across sessions - Bracketed paste -- paste blocks of code instantly - Job control -- Ctrl+Z suspends, fg resumes cleanly - Interrupt -- Ctrl+C cancels input or interrupts evaluation Evaluate expressions: $ glj -e '(println "Hello, World!")' Hello, World! $ glj -e '(apply + (range 3 10))' 42 $ glj -e ' (defn factorial [n] (if (<= n 1) 1 (* n (factorial (dec n))))) (factorial 5)' 120 Run a Clojure script: ;; hello.glj (println "Hello," (first *command-line-args*)) $ glj hello.glj World Hello, World Create executable programs: ;; server.glj (ns example.server) (defn echo-handler [w r] (io.Copy w (.Body r)) nil) (net:http.Handle "/" (net:http.HandlerFunc echo-handler)) (println "Server starting on :8080...") (net:http.ListenAndServe ":8080" nil) $ glj server.glj Server starting on :8080... You can also embed Glojure as a scripting language within your Go applications. This is useful when you want to: - Add scriptable configuration to your Go application - Allow users to extend your application with Clojure plugins - Mix Go's performance with Clojure's expressiveness - Control the execution environment (custom I/O, sandboxing) Basic embedding example: package main import ( "fmt" _ "github.com/glojurelang/glojure/pkg/glj" // Initialize Glojure "github.com/glojurelang/glojure/pkg/runtime" ) func main() { // Evaluate Clojure code result := runtime.ReadEval(` (defn factorial [n] (if (<= n 1) 1 (* n (factorial (dec n))))) (factorial 5) `) fmt.Printf("5! = %v\n", result) // 5! = 120 } Calling Go from Clojure and vice versa: package main import ( "fmt" "github.com/glojurelang/glojure/pkg/glj" "github.com/glojurelang/glojure/pkg/runtime" ) // Define a Go function func greet(name string) string { return fmt.Sprintf("Hello, %s from Go!", name) } func main() { // Make the Go function available to Clojure runtime.ReadEval(`(def greet-from-go nil)`) // placeholder greetVar := glj.Var("user", "greet-from-go") greetVar.SetRoot(greet) // Use it from Clojure result := runtime.ReadEval(`(greet-from-go "Clojure")`) fmt.Println(result) // "Hello, Clojure from Go!" // Call a Clojure function from Go runtime.ReadEval(`(defn add [x y] (+ x y))`) addFn := glj.Var("user", "add") sum := addFn.Invoke(10, 32) fmt.Printf("Sum: %v\n", sum) // Sum: 42 } Accessing your own Go packages: When embedding Glojure, you can also expose your own Go packages or additional standard library packages using the package map approach described in the Accessing additional Go packages section below. This allows embedded Clojure code to access any Go packages you choose to expose: import ( _ "github.com/glojurelang/glojure/pkg/glj" _ "your.app/gljimports" // Your generated package map ) // Now Clojure code can access your exposed packages runtime.ReadEval(` (your$package.YourFunction "arg") (another$package.Method) `) Use glj command for: - Writing standalone Clojure programs - Interactive development with the REPL - Running Clojure scripts - Evaluating expressions directly from the command line - Learning Clojure with Go interop Embed Glojure for: - Adding scripting to an existing Go application - Building a platform that users extend with Clojure - Custom control over the Glojure execution environment - Mixing Go and Clojure in a single binary Glojure ships with interop with many standard library packages out-of-the-box. Go package names are munged to avoid ambiguity with the use of / to refer to namespaced symbols; instances of / in package names are replaced with : . Here's a simple example: user=> (println (fmt.Sprintf "A couple of HTTP methods: %v" [net:http.MethodGet net:http.MethodPost])) A couple of HTTP methods: ["GET" "POST"] nil The following standard library packages are included by default: bytes context errors flag fmt io io/fs io/ioutil math math/big math/rand net/http os os/exec os/signal regexp reflect sort strconv strings sync sync/atomic time unicode To expose additional packages, you must generate a "package map" and compile your own executable that imports both your package map and the Glojure API. See the section below for more details. Expect improvements to both the availability of standard library packages and interop workflows. The gen-import-interop can be used to emit the contents of a .go file that will export a function that can be used to add the exports of additional packages to the Glojure package map. $ go run github.com/glojurelang/glojure/cmd/gen-import-interop \ -packages=:comma-separated-package-list: \ > your/package/gljimports/my_package_map.go Then, in your own program: package main import ( // Add your packages' exports to the pkgmap. _ "your.package/gljimports" ) // ... | Clojure Type | Glojure Type | Notes | |---|---|---| long | int64 | | double | float64 | | float | float32 | | byte | byte | Note that Go bytes are unsigned, whereas JVM bytes are signed. | short | int16 | | int | int | Note that JVM ints are 32-bit, whereas Go ints are 32- or 64-bit depending on the platform. | char | lang.Char | The Glojure type is a tagged rune (type Char rune ). JVM chars are 16-bit whereas Go runes are 32-bit. | BigInt | *lang.BigInt | The Glojure type wraps *big.Int . | BigDecimal | *lang.BigDecimal | The Glojure type wraps *big.Float . | Ratio | *lang.Ratio | The Glojure type wraps *big.Rat . | BigInteger | *big.Int | Native JVM BigInteger corresponds to *big.Int . | | Aspect | Glojure | Joker | let-go | |---|---|---|---| | Hosted1 | Yes | No | No | | Extensible Go interop | Yes | No | No | | Concurrency | Yes | Yes (with GIL) | Yes | | Clojure tooling (e.g. linter) | No | Yes | No | | Execution | Tree-walk interpreter | Tree-walk interpreter | Bytecode Interpreter | If you'd like to see another port in this table, or if you believe there is an error in it, please file an issue or open a pull request! Footnotes - What does it mean to be a hosted language? For Clojure on the JVM, it means that all Java values are also Clojure values, and vice versa. Glojure strives to maintain the same relationship with Go. ↩