REPL

Interactive Elixir REPL with AST-based sandboxing. Three safety levels: wide open for local use, locked down for SSH. Bindings persist between evaluations, IO gets captured, and runaway code hits a timeout.

Quick Start

mix raxol.repl
mix raxol.repl --sandbox standard
mix raxol.repl --sandbox strict
mix raxol.repl --timeout 10000

Evaluator

Raxol.REPL.Evaluator is a functional wrapper around Code.eval_string. It spawns evaluation in a monitored process with a timeout, swaps the group leader to capture IO, and carries bindings forward between calls.

alias Raxol.REPL.Evaluator

evaluator = Evaluator.new()

{:ok, result, evaluator} = Evaluator.eval(evaluator, "x = 1 + 2")
result.value      # => 3
result.output     # => "" (captured IO -- empty here)
result.formatted  # => "3"

# Bindings carry over
{:ok, result, evaluator} = Evaluator.eval(evaluator, "x * 10")
result.value      # => 30

# IO gets captured
{:ok, result, _} = Evaluator.eval(evaluator, ~s[IO.puts("hello")])
result.output     # => "hello\n"

# Runaway code times out (default 5000ms)
{:error, "Evaluation timed out", evaluator} =
  Evaluator.eval(evaluator, "Process.sleep(:infinity)", timeout: 1000)

Evaluator.bindings(evaluator)  # => [x: 3]
Evaluator.history(evaluator)   # => [{"x * 10", result}, ...]

evaluator = Evaluator.reset_bindings(evaluator)  # clears bindings, keeps history
evaluator = Evaluator.clear_history(evaluator)    # clears history, keeps bindings

Sandbox Levels

Raxol.REPL.Sandbox walks the AST with Macro.prewalk and rejects code that calls blocked modules or functions -- before it ever runs.

alias Raxol.REPL.Sandbox

Sandbox.check("Enum.map([1,2,3], & &1 * 2)", :standard)  # => :ok
Sandbox.check("System.cmd(\"rm\", [\"-rf\", \"/\"])", :standard)  # => {:error, ["..."]}

Standard blocks: System.cmd, System.shell, File.rm, File.rm_rf, File.write, Port.open, Code.eval_string, Code.eval_quoted, :os.cmd, and friends.

Strict only allows: Enum, Stream, Map, Keyword, List, Tuple, MapSet, String, Integer, Float, Atom, IO, Kernel, Range, Regex, Date, Time, DateTime, NaiveDateTime, Calendar, Access, Base, URI, Jason, Inspect. Everything else gets rejected.

Over SSH

The playground serves a REPL demo over SSH:

mix raxol.playground --ssh

Use :strict sandbox for anything exposed to the network.

Playground Demo

The REPL is one of the playground demos (mix raxol.playground -> REPL). It has input history (up/down), formatted output, a bindings panel, and shows the active sandbox level.