chaser

A little something to go with your dialtone.

A terminal nREPL client, taken neat. chaser speaks the plain nREPL protocol, so it works with dialtone (Erlang), repartee (Elixir), and any other conformant server - Clojure's included. Following family tradition, the drink name sits on the client side of the bar, next to CIDER, Port and neat.

A session

$ chaser                       # picks up .nrepl-port automatically
chaser 0.1.0 | nrepl://127.0.0.1:51234 | dialtone 0.1.0 / erlang 29
127.0.0.1:51234> io:format("computing~n"), 6 * 7.
computing
=> 42
127.0.0.1:51234> 1 div 0.
!! error:badarith
   exception error: an error occurred when evaluating an arithmetic expression
     in operator  div/2
        called as 1 div 0
127.0.0.1:51234> F = fun(X) ->
             ..>   X * 2
             ..> end.
=> #Fun<erl_eval.42.39164016>
127.0.0.1:51234> :doc lists:map
lists:map map(Fun, List1)
  ...
127.0.0.1:51234> :quit

Printed output streams as the program writes it; values arrive on their own line behind a green =>; errors behind a red !! with the trace indented. The separation survives NO_COLOR and pipes.

The good parts

• TAB completion, server-side. Completion candidates come from the server's completions op, so they know your session: your variables, your aliases, the modules actually loaded. Candidates render grouped by kind (functions / modules / variables), the way the Erlang shell displays them. One TAB extends the common prefix, another lists.
• Language-aware input. chaser infers the server's language from describe: Erlang input submits on a terminating ., Elixir when brackets and do/end balance, anything else on Enter (--lang overrides). A ..> prompt continues multi-line forms.
• Interrupts without ceremony. A long-running eval prints a hint after a second; bare Enter interrupts it. Session state survives - that's the server's contract.
• stdin round-trips. When evaluated code reads input, the server says need-input and whatever you type next is fed to the program.
• Line editing and history for free: chaser rides OTP's own edlin/tty machinery (shell:start_interactive/1), with persistent history under your user cache directory.
• Pipes work. With stdin or stdout not a terminal, chaser drops prompts and colors: echo '1 + 2.' | chaser :51234 prints => 3.

Usage

chaser [HOST][:PORT] [--host HOST] [--port PORT]
       [--lang erlang|elixir|none] [--no-color] [--pipe]

Without a port, chaser walks up from the current directory looking for an .nrepl-port file - the convention every nREPL server follows, dialtone and repartee included.

Build it with rebar3 escriptize (OTP 26+); the result is a single chaser file you can put on your PATH. bin/chaser builds on demand during development.

Commands

Input	Effect
TAB	complete via the server's completions op
:doc SYM	documentation via the server's lookup op
:help	list commands
:quit	leave (Ctrl-D at the prompt does the same)
Enter	during a running eval: interrupt it

License

Apache License 2.0.