A REPL for Dart.

Prior art

Based on early version of a proof of concept REPL environment for Dart from a pair of articles by Andreas Kirsch and an example in the Dart SDK tests and the recharge package


  • X MVP with expression evaluation
  • X Use code from BlackHC's work to parse input for statements vs expressions
  • X Use cli_repl for better repl ergonomics
  • X Use standard pub activate for package to run its binary instead of shell script
  • X Improve usage documentation
  • X Use hotreload with a scratchpad file
  • ?? Support built in package imports
  • ?? Support arbitrary package imports
  • ?? Use scratchpad with dedicated Isolate

?? - not clear if this is a workable approach


To install the repl use:

dart pub global activate repl

Then as long as the pub system cache is on your path you can run it using: drepl

Supported features

You can currently use expressions and statements as well as a few built-in's are supported (see below), its already possible to do a few useful things with the REPL.

For instance you can do JS style IIFE's:

> (){final data = ['this', 'is', 'a', 'test']; for(int i = 0; i < data.length; i++) print(data[i]); }()

But of course that is a bit contrived an example as you could also do:

> ['this', 'is', 'a', 'test'].forEach((x) => print(x))

Some statements are also possible, eg.

> int sqr(int a) => a*a;

> sqr(5)
> 25


print() - print to output reload() - trigger a hot-reload (doesn't work well at the moment)

Editing, History, Shortcuts

see the cli_repl package documentation for supported short-cut keys.


Clone this repo, then from the top level of this repo and then run using:

dart bin/main.dart

Future plans

A more powerful though much more involved implmentation route would be to use the Dart embedding API, perhaps via FFI to avoid needing to deal with too much c/c++ dev, assuming its possible for DartVM to call into itself via FFI using the embedding api?


All contributions: PRs, bug reports, feature requests, documentation are most welcome.

Contribution guidelines: TODO.