When comparing Pharo vs Boo, the Slant community recommends Boo for most people. In the question“What are the best languages to learn for someone coming from Python?” Boo is ranked 10th while Pharo is ranked 14th. The most important reason people chose Boo is:
The open-source [#develop](http://www.icsharpcode.net/OpenSource/SD/Default.aspx) comes with Boo support.
Ranked in these QuestionsQuestion Ranking
In Pharo everything is an object. Compiler - object, network - object, method - also an object. And objects communicate with messages. No operators, no control-flow statements. Just objects and messages. Few things to learn, but you can learn OOP well.
Pro Easily learnt
There is good, free documentation including several books written by experts with extensive examples. There is an online MOOC. There are many tutorial videos. Supportive conferences and community. Even a professional support option if desired.
Pro Live updates
The nature of Pharo being a "live" environment allows you to perform live updates to your system without requiring to restart it. You can upgrade/modify classes while serving requests at the same time.
Pro Highly productive
The framework for developing sophisticated web applications in Smalltalk is developed in Pharo. Seaside lets you build highly interactive web applications quickly, reusably and maintainably.
Pro Remote debugging
Pro Beautiful coding patterns in your IDE
No need to search google for compact beautiful examples of how to do things, your live environment source is available and you can easily live search, see how it works and copy how the masters would do it (examples most languages still copy too).
Pro Glamorous toolkit & GTInspector
Most languages are still copying the Smalltalk tools of yesterday - GTInspector (written in Glamorous) takes live exploration of code/running objects to a new level. It's really slick, and better yet, you can easily write your own inspectors in 10 lines of code.
Pro Code can be run on rock solid GemStone environment
Pro 64 bit support as of Pharo 7
Use 32 bit or 64 bit versions of Pharo on Windows, Mac & Linux
Pro Advanced code analysis tools
MOOSE environment provides extensive, easily leveraged and class leading tools for code analysis and improvement.
Pro Can run headless for production
Pro Really simple networking and REST with Zinc
Pro Graphics, graphing and visualisation framework - Roassal
Roassal and Mondrian provide fantastic and easily used frameworks for graphics, graphing and advanced visualisations (comparable to D3.js) but with much less code. Visualisations can be rendered into web friendly graphics (SVG, .png etc.) without additional work.
Pro IDE support
The open-source #develop comes with Boo support.
Pro Static type safety
This also improves performance as compared to IronPython. You can still use duck typing if you want, but you mostly don't need to since Boo can infer the type based on context.
Pro Inter-operates with other .NET languages
Boo runs on the .NET platform, so you can pretty much use it for anything C# is good for.
Pro One of Unity's supported languages
Use your Python skills to make games.
Pro Familiar syntax
Boo's syntax was heavily influenced by Python's, but makes some improvements like macros and multi-line lambdas.
Con Small community
But they are very friendly and supportive. Best help comes through the mailing lists so not always easily googlable. There is also a Slack community where help is nearly instantaneous.
Con Single threaded
Pharo's VM only ever uses one CPU core. If you want to write code that uses more than one CPU core, you need to jump through hoops such as running multiple VMs and synchronising your data.
Con No stable 64 bit VM on Windows yet (work-in-progress)
64 bit support is on its way for Windows (experimental). Pharo 7 has 64 bit support for Mac and Linux as of Pharo 7.
Con The documentation isn't as good as Python's
There are some Boo textbooks. You can also find examples of Boo's language features in the Git repository, but it doesn't seem to have a thorough description of the language itself like Python does.