When comparing Smalltalk vs APL, the Slant community recommends Smalltalk for most people. In the question“What is the best programming language to learn first?” Smalltalk is ranked 15th while APL is ranked 55th. The most important reason people chose Smalltalk is:
You can modify the system as it's running. You're "swimming with the fish", instead of probing a black box by remote control.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Environment of live objects
You can modify the system as it's running. You're "swimming with the fish", instead of probing a black box by remote control.
Pro Easy to learn and experiment
Pro Inspector makes objects transparent
Programmers must make detailed mental models of the system they are developing. Bugs usually happen when the mental model does not match the actual system. This is one of the greatest difficulties beginners have because most systems are so opaque. It takes a lot of effort to see what's really going on. But in Smalltalk this is much easier, thanks to the powerful tools included in the environment, like the object inspector.
Pro Superb Integrated Development Environment (IDE)
All tools (Inspector, Browser, Debugger etc.) are written in Smalltalk and are live objects in the environment. All sources are present, so that the tools can easily be studied, changed and experimented with.
The same goes for the other components like the compiler, OS-Integration etc.
Pro Pure and easy object orientation
Smalltalk is one of few languages that are purely object oriented. This provides a solid and easy to understand base on which to learn object oriented programming, the most popular approach to programming.
Pro Elegant syntax fits on a postcard
The syntax was designed to be easy enough for children to learn. Beginners can learn the language rules very quickly and then focus on programming without fighting the syntax at the same time. Things that have to be baked into the grammar in other languages are simple message sends with block arguments in Smalltalk. Expressions have only three precedence levels to worry about.
Pro Agile "interactive" test-driven development
Smalltalk had the original (and still the best) unit test system that inspired it in many other languages (like Java's JUnit). Working with interactive live objects in Smalltalk style TDD makes it easy to teach and learn TDD.
Pro Powerful integrated debugger
You can edit code and swap it in while the program is still running after an exception has already been signaled, or restart from anywhere in the call stack. You can inspect and modify the state of any object. Some Smalltalkers write unit tests and then program exclusively in the debugger.
Pro Internal source code and documentation
You can explore how everything works easily.
Pro Incremental compilation
Smalltalk provides an extremely fast code-compile-run-debug cycle. You don't have to stop and reset the world to tweak your program, since you can compile one method at a time while the environment is still running. This is great for beginners to experiment and prototype ideas.
Pro Inspired many other languages' object systems
Pro Open source
MIT licensed implementations Pharo, Squeak, Cuis & Dolphin
and GPL licensed GnuSmalltalk.
Pro Save and restore virtual machine image
A Smalltalk environment can save the state of a running program and later restore and resume execution. This includes the internal state of live objects, multiple thread stacks, and debugging sessions, making it easier for beginners to take the exact problem to an expert for assistance.
Pro Language uniformity
This leads to a very simple programming model (pure OO) that is still very powerful. A lot of stuff that is hard to implement in other languages is easier in Smalltalk.
Pro Graphical user interface
Beginners are usually stuck making command-line applications in other languages, because GUIs are too hard. Smalltalk GUIs are easy enough to start with.
Pro First-class functions with lexical closures
Also known as "blocks". These objects contain reusable snippets of code and as first-class objects they can be passed as arguments to other methods or blocks and also returned from them. "lexical closures" mean they retain access to the variables in the lexical environment they were written in, that is, in the surrounding code.
Pro It invented a lot of stuff
Smalltalk is the inventor of Just-in-Time compilation and the MVC concept, refactoring through their so-called refactoring browser and it was also one of the first adopters of a language virtual machine, closures, live programming, test driven development, an IDE and the development of GUI`s.
Pro As a first language, almost forces you to learn OO design
Hybrid languages (e.g., Java, C#, C++) make it easy to slip into procedural thinking. Smalltalk's pure OO approach makes it hard not to think in object-oriented terms. In addition, since the entire IDE and runtime components are there in the image for you to browse, you have plenty of examples of good OO design to learn from.
Pro Provides a functional way to interact with objects
Many languages today use object orientation, while the most of them stock on the half way in that perspective.
Smalltalk sees literally everything as an object and this includes things like the classes and primitive data types. There is are zero control structures such as selection and iteration, since all is done by sending messages to objects.
It use a lot of concepts from Lisp in order to provide a nice experience for this pure kind of object orientation.
It provides immutable data structures, closures, anonymous functions and higher order functions, while all those functions are objects. This is what makes Smalltalk so simple, elegant, and easy.
All this counts for Pharo, while other implementations as Amber are probably feature complete to it.
Pro High-level
No complicated loop processing to apply a function to a array of arrays. Functions are defined in a way that they will typically operate the same way on any number of array dimensions. This, along with the clear syntax, leads to very compact code that can be comprehended in a single line, rather than spread out over many pages.
Pro Iverson award in 2016
Pro Very concise
Pro Clear syntax
There is no operator precedence to memorize, as everything is evaluated right-to-left. E.g., in APL 3*10+3 = 39. You do have to type in some otherwise unusual characters, such as ↓ and ∊, but those are easy enough to pick up -- and they have the advantage of being easily remembered once understood, as they often have some connection to common mathematical symbols.
Pro Terse
You can seriously implement Conway's Game of Life in one line. There's a reason we do algebra with symbols instead of story problems. APL is good as a language of thought, since you can hold entire algorithms in your head at once.
Cons
Con OO is becoming obsolete
Smalltalk did it best, but the whole paradigm is a poor fit for the expected future multicore processors. Isolated mutable variables with no compile checks is a recipe for race conditions in multithreaded code. Beginners would be better off learning a functional language.
Con Not common
Smalltalk missed an opportunity to become mainstream when its implementations cost $5000 per seat versus $0 open source. New open source implementations (Pharo, Squeak) have minor corporate backers but not yet an IT behemoth. Direct jobs are scarce (but indirectly Smalltalk experience is very well regarded). Online communities are relatively small.
Con Not useful for mobile development
While Smalltalk is very powerful and easy to learn, it doesn't have a well supported mobile distribution, but you'll be spoiled for working in mainstream languages like Java, Swift or Kotlin where jobs are more readily available.
Con Virtual machine in its own isolated world
Smalltalk wants to be the whole OS. While this has tremendous advantages internally, interacting with the world outside the VM is not as easy as pure Smalltalk and must be done via a Foreign Function Interface.
Con Non-standard arithmetic ordering
Since every operation is considered a message sent sent is a specific order, all arithmetic operators have the same precedence. E.g. 2 + 3 x 4 translates to 2 + 3, and the result is multiplied by 4, giving an answer of 24 (instead of the correct answer - 14). Once you are learn this, it can easily handled using brackets, e.g. 2 + (3 x 4), but still a momentary suprise for beginners.
Con Hieroglyphics
APL symbols are only used by APL. You have to learn how to type them and how to read them. It doesn't work well with standard text editors , version control systems, search engines, or web forums. This makes it difficult for a beginner to find help.
Con Does not prepare you for most of the practical programming languages of today
While APL does have a strong use in certain areas (mostly mathematically intensive applications), it is a Domain-Specific language. That along with the fact that its syntax is not similar to C-like or other common syntax forms means that learning APL and expecting it to help you with learning other languages is like learning Calculus and expecting it to make English easier.
Con Write-only language
Maybe you can learn to read it with experience. And an interpreter. Reading APL is like reading a college math book. You might have to study a single line for fifteen minutes to understand what it's doing. And that's if you're an expert at APL. This also applies if you wrote it yourself more than a month ago. hopefully you have comments.
Con Flawless diamond
You can't extend the language itself. (J does this better.) Of course, what's built in is quite powerful.