When comparing Scheme vs Pharo, the Slant community recommends Scheme for most people. In the question“What is the best programming language to learn first?” Scheme is ranked 2nd while Pharo is ranked 28th. The most important reason people chose Scheme is:
Scheme syntax is extremely regular and easy to pick up. A *formal* specification of the syntax fits onto just a few pages; it can be introduced informally in a paragraph or two. Students are not distracted by remembering how to write if statements or loops or even operator precedence because every syntactic follows the same pattern. Ultimately, everything looks something like this: (func a b c) This includes not only user-defined functions but even control flow: (if cond then-clause else-clause) or even primitive operations like `define` and `set`: (define foo 10) (set! foo 11) This means that nothing really has special syntactic treatment in the language. There are essentially no weird edge-cases to memorize, and different concepts are given a more equal weight in the language. (Unlike Algol-like languages which tend to given undue weight to loops and assignment statements, for example.)
Ranked in these QuestionsQuestion Ranking
Pro Simple syntax
Scheme syntax is extremely regular and easy to pick up. A formal specification of the syntax fits onto just a few pages; it can be introduced informally in a paragraph or two. Students are not distracted by remembering how to write if statements or loops or even operator precedence because every syntactic follows the same pattern.
Ultimately, everything looks something like this:
(func a b c)
This includes not only user-defined functions but even control flow:
(if cond then-clause else-clause)
or even primitive operations like
(define foo 10) (set! foo 11)
This means that nothing really has special syntactic treatment in the language. There are essentially no weird edge-cases to memorize, and different concepts are given a more equal weight in the language. (Unlike Algol-like languages which tend to given undue weight to loops and assignment statements, for example.)
Pro No Magic - it's clear how everything works
Scheme has far less built into the language itself, helping students see that things like OOP are not magical: they are just patterns for organizing code. Everything in Scheme is built up from a very small set of primitives which compose in a natural and intuitive fashion.
Having a language that does not accord many things special status helps keep students open minded. This will help students later go between different languages and paradigms from procedural to object-oriented to functional.
Pro Great at teaching fundamental programming ideas
Scheme teaches the important, fundamental ideas immediately without the distraction of unnecessary syntax or language features.
Pro Great, well known textbooks
There is a set of very strong textbooks introducing CS and programming using Scheme. These books are available for free online.
The most famous example--and one of the most famous CS books full stop--is Structure and Interpretation of Computer Programs usually known as SICP. This book introduces fundamental ideas in computer science and covers an incredible amount of material quickly and clearly without requiring any prior knowledge.
However, some people find SICP a bit challenging as a first text. Happily, there are other more introductory texts as well. Simply Scheme is a book designed to be read before SICP, easing beginners into the language as well as CS and programming in general. How to Design Programs is another text used in introductory college courses.
Pro Robust metaprogramming
The quotation functionality of Lisp allow for extremely powerful, yet syntactically straightforward metaprogramming via macros. This is more powerful than the C preprocessor while being less involved than something like Template Haskell or F# quotations.
Using macros to properly decompose a problem domain teaches new developers good habits, improving composibility and reliability when tackling large programs. Scheme metaprogramming also serves as a gentle introduction to domain specific languages.
Unlike most languages, Scheme actually accords both functional programming and imperative programming roughly equal status. Many other languages like Python and Java are staunchly imperative while SML and Haskell are primarily functional; Scheme is a nice middle ground.
Additionally, since Scheme syntax is extremely flexible, it can easily be re-purposed for teaching non-deterministic and logic programming. There is no need to learn a new language like Prolog when the same ideas can easily be expressed with Scheme syntax.
This gives students a good perspective on different ways to think about and organize programs, which makes it much easier to move forward to other languages and technologies.
Pro Multi platform
GNU/Linux, OS X, and Windows versions available.
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 Advanced code analysis tools
MOOSE environment provides extensive, easily leveraged and class leading tools for code analysis and improvement.
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 Can run headless for production
Pro Highly productive
Pro Remote debugging
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 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
Con Little Job Market
There are little to none jobs searching for a Scheme programmer. The ones that exist are more related to Research in Maths or Artificial Intelligence.
Con Fragmented ecosystem
Scheme is an IEEE standard, not an implementation. Unfortunately, the standard is too minimal and practical implementations have diverged--they had to expand on the standard to get anything done, but did so in incompatible ways.
The later de facto standard R6RS tried to correct this, but lost Scheme's minimalist elegance in the process. The newer R7RS standard takes the best of both worlds with an elegant minimalist core and a practical standard library.
Con Very different semantics from mainstream programming languages
Con A language that is purely academic
If someone said "I am starting a project in Scheme" then they are either talking about their homework or they are starting a joke.
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 No 64 bit VM
Although 64 bit support is on its way, there is no official VM to work in a 64 bit system, requiring you to use 32 bit libraries.
Available in Pharo 5.