Glojure
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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.
Prerequisites
Before you get started with Glojure, make sure you have installed
and have knowledge of Go (version 1.19 or higher).
Installation
Glojure is currently available from source for all platforms where Go
can run, and it requires at least go 1.19.
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=>
Usage
Here's a small example program that starts an HTTP server with a
simple handler function that responds with the request body:
;; example.glj
(ns example.server)
(defn echo-handler
[w r]
(io.Copy w (.Body r))
nil)
(net$http.Handle "/" (net$http.HandlerFunc echo-handler))
(net$http.ListenAndServe ":8080" nil)
Run it with the glj
command:
$ glj ./example.glj
$ curl localhost:8080 -d "sicp"
sicp
Interop
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.
Accessing additional Go packages
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"
)
// ...
Differences from Clojure
Numbers
Clojure Type |
Glojure Type |
Notes |
long |
int64 |
|
double |
float64 |
|
float |
float32 |
|
double |
float64 |
|
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 . |
Comparisons to other Go ports of Clojure
Aspect |
Glojure |
Joker |
let-go |
Hosted[^1] |
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!
[^1]: 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.