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Small Clojure Interpreter

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A tiny implementation of Clojure in Clojure.


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.


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


Use as a dependency:

[borkdude/sci "0.0.4"]


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

Currently the following special forms/macros are supported: function literals (#(inc %)), fn, defn, quote, do,if, when, let, and, or, ->, ->>, as->.

In sci, defn does not mutate the outside world, only the evaluation context inside a call to sci/eval-string.

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}})

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


To make the rand-* functions behave well when compiling to a GraalVM native binary, use this setting:



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:


For running individual tests, see the scripts in script/test.


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.

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