Small Clojure Interpreter

A tiny implementation of Clojure in Clojure.

Rationale

You want to evaluate code from user input, but eval isn't safe or simply doesn't work.

This library works with:

• Clojure on the JVM
• Clojure compiled with GraalVM native
• ClojureScript, even when compiled with :advanced

It is used as the interpreter for babashka.

Status

Experimental. Breaking changes are expected to happen at this phase.

Installation

Use as a dependency:

[borkdude/sci "0.0.1"]

Usage

(require '[sci.core :as sci])
(sci/eval-string "(inc 1)") => ;; 2
(sci/eval-string "(inc x)" {:bindings {'x 2}}) ;;=> 3

Anonymous function literals are allowed with currently up to three positional arguments. This is an arbitrary limit and may be changed in the future.

(sci/eval-string "(#(+ %1 %2 %3) 1 2 3)") => ;; 6

Currently, only the following special forms/macros are supported: quote, if, when, let, and, or, ->, ->>, as->.

By default sci only enables access to the pure non-side-effecting functions in Clojure. More functions can be enabled, at your own risk, using :bindings:

user=> (sci/eval-string "(println \"hello\")" {:bindings {'println println}})
hello
nil

More examples of what is currently possible can be found at babashka.

Test

Required: lein, the clojure CLI and GraalVM.

To succesfully run the GraalVM tests, you will have to compile the binary first with script/compile.

To run all tests:

script/test

License

Copyright © 2019 Michiel Borkent

Distributed under the Eclipse Public License 1.0. This project contains code from Clojure and ClojureScript which are also licensed under the EPL 1.0. See LICENSE.