TREPL: A REPL for Torch

  ______             __   |  Torch7
 /_  __/__  ________/ /   |  Scientific computing for LuaJIT.
  / / / _ \/ __/ __/ _ \  |
 /_/  \___/_/  \__/_//_/  |  https://github.com/torch
                          |  http://torch.ch

th>

A pure Lua REPL for LuaJIT, with heavy support for Torch types.

Uses Readline for tab completion.

This package installs a new binary named th, which comes packed with all these features:

Features:

Tab-completion on nested namespaces
Tab-completion on disk files (when opening a string)
History
Pretty print (table introspection and coloring)
Auto-print after eval (can be stopped with ;)
Each command is profiled, timing is reported
No need for '=' to print
Easy help with: ? funcname
Self help: ?
Shell commands with: $ cmd (example: $ ls)
Print all user globals with who()
Import a package's symbols globally with import(package)
Require is overloaded to provide relative search paths: require('./mylocallib/')
Optional strict global namespace monitoring
Optional async repl (based on async)

Install

Via luarocks:

luarocks install trepl

Launch

We install a binary, simple to remember:

th
> -- amazing repl!

Alternatively, you can always bring up the repl by loading it as a lib, from anywhere:

luajit
> repl = require 'trepl'
> repl()

Use

Completion:

> cor+TAB   ...  completes to: coroutine

History:

> ARROW_UP | ARROW_DOWN

Help (shortcut to Torch's help method):

> ? torch.FloatTensor
prints help...

Shell commands:

> $ ls
README.md
init.lua
trepl-scm-1.rockspec

[Lua # 2] > $ ll
...

> $ ls
...

History / last results. Two variables are used:

_RESULTS: contains the history of results:

> a = 1
> a
1
> 'test'
test
> _RESULTS
{
   1 : 1
   2 : test
}

_LAST: contains the last result
> _LAST
test

Convenient to get output from shell commands:
> $ ls -l
> _LAST
contains the results from ls -l, in a string.

Hide output. By default, TREPL always tries to dump the content of what's evaluated. Use ; to stop it.

> a = torch.Tensor(3)
> a:zero()
0
0
0
[torch.DoubleTensor of dimension 3]

> a:zero();
>

Helpers

Colors libraries can be loaded independently:

> c = require 'trepl.colorize'
> print(c.red('a red string') .. c.Blue('a bold blue string'))

Globals

Global variables are a well known issue with Lua. th can be run with a flag -g that will monitor global variables creation and access.

Creation of a variable will generate a warning message, while access will generate an error.

th -g
> require 'sys';
created global variable: sys @ [c-module]
> a = 1
created global variable: a @ a = 1
> b
error: attempt to read undeclared variable b

Async repl [BETA]

An asynchronous repl can be started with -a. Based on async, this repl is non-blocking, and can be used to spawn/schedule asyncrhonous jobs. It is still beta, and does not yet have readline support:

th -a
> idx = 1
> async.setInterval(1000, function() print('will be printed every second - step #' .. idx) idx = idx + 1 end)
will be printed every second - step #1
will be printed every second - step #2
will be printed every second - step #3
> idx = 20
will be printed every second - step #20
will be printed every second - step #21