When comparing Lua vs Haskell, the Slant community recommends Lua for most people. In the question“What is the best programming language to learn first?” Lua is ranked 16th while Haskell is ranked 26th. The most important reason people chose Lua is:
One of the best features of Lua is its very well designed C API. This is very useful if you have an existing C library you need to integrate with Lua or quickly get a Lua script running on the C side of the game. Finally Lua plays so nice with C that if you need to optimise for speed you can re-write it in C a lot easier than other languages.
Specs
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Pros
Pro Very easy to integrate with C and C++
One of the best features of Lua is its very well designed C API. This is very useful if you have an existing C library you need to integrate with Lua or quickly get a Lua script running on the C side of the game.
Finally Lua plays so nice with C that if you need to optimise for speed you can re-write it in C a lot easier than other languages.
Pro Great documentation
The official Lua documentation is very helpful and thorough. There are also a large number of online resources or books with lots of helpful information for beginners and advanced users alike.
Pro Portable
Lua can be built on any platform with a ANSI C compiler.
Other than that, Lua is extremely small. For example, the tarball for Lua 5.2.1 is only 245K compressed and 960K uncompressed (including documentation).
When built on Linux, the Lua interpreter built with the standard libraries takes 182K and the Lua library takes 243K.
The small size and the ability to build with a C compiler make Lua an extremely portable language that can run on a lot of different systems and computers.
Pro Simple
Easy to learn.
Pro Fast
Lua's performance compares very well to other languages, If performance needs to be further improved you can:
- Implement critical parts in C
- Use the LuaJIT compiler. The LuaJIT compiler is a drop in replacement for the stock compiler and provides significant performance improvements. From the overview page:
LuaJIT speeds can rival code written in C.
Pro Embeddable
Many different game engines (e.g. Elder Scrolls series, ToME) use Lua for scripting, and it's runtime is designed for embedded use.
Pro Clean and simple syntax suitable for beginners
The Lua syntax is modeled from Modula, a language known for being a fantastic introduction to programming.
The Lua syntax also has the following key characteristics:
- Semicolon as a statement separator is optional (mostly used to resolve ambiguous cases as in a = f; (g).x(a)).
- Syntactic sugar for function calls (f'string', f"string", f[[string]], and f{table}) and method calls (obj:m()).
Pro Helpful community
Due to the growing popularity, Lua has a rather large and helpful community surrounding it.
Pro Highly transferable concepts
Haskell's referential transparency, consistency, mathematics-oriented culture, and heavy amount of abstraction encourage problem solving at a very high level. The fact that this is all built upon little other than function application means that not only is the thought process, but even concrete solutions are very transferable to any other language. In fact, in Haskell, it's quite common for a solution to simply be written as an interpreter that can then generate code in some other language. Many other languages employ language-specific features, or work around a lack of features with heavy-handed design patterns that discourage abstraction, meaning that a lot of what is learned, and a lot of code that is needed to solve a particular problem just isn't very applicable to any other language's ecosystem.
Pro Forces you to learn pure functional programming
It is pure and does not mix other programming paradigms into the language. This forces you to learn functional programming in its most pure form. You avoid falling back on old habits and learn an entirely new way to program.
Pro Open source
All Haskell implementations are completely free and open source.
Pro Mathematical consistency
As Haskell lends itself exceedingly well to abstraction, and borrows heavily from the culture of pure mathematics, it means that a lot more code conforms to very high-level abstractions. You can expect code from vastly different libraries to follow the same rules, and to be incredibly self-consistent. It's not uncommon to find that a parser library works the same way as a string library, which works the same way as a window manager library. This often means that getting familiar and productive with new libraries is often much easier than in other languages.
Pro Referentially transparent
Haskell's Purely Functional approach means that code is referentially transparent. This means that to read a function, one only needs to know its arguments. Code works the same way that expressions work in Algebra class. There's no need to read the whole source code to determine if there's some subtle reference to some mutable state, and no worries about someone writing a "getter" that also mutates the object it's called on. Functions are all directly testable in the REPL, and there's no need to remember to call methods in a certain order to properly initialize an object. No breakage of encapsulation, and no leaky abstractions.
Pro Hand-writeable concise syntax
Conciseness of Haskell lets us to write the expression on the whiteboard or paper and discuss with others easily. This is a strong benefit to learn FP over other languages.
Pro Very few language constructs
The base language relies primarily on function application, with a very small amount of special-case syntax. Once you know the rules for function application, you know most of the language.
Pro Quick feedback
It's often said that, in Haskell, if it compiles, it works. This short feedback loop can speed up learning process, by making it clear exactly when and where mistakes are made.
Pro Functions curry automatically
Every function that expects more than one arguments is basically a function that returns a partially applied function. This is well-suited to function composition, elegance, and concision.
Pro Easy to read
Haskell is a very terse language, particularly due to its type inference. This means there's nothing to distract from the intent of the code, making it very readable. This is in sharp contrast to languages like Java, where skimming code requires learning which details can be ignored. Haskell's terseness also lends itself to very clear inline examples in textbooks, and makes it a pleasure to read through code even on a cellphone screen.
Pro Popular in teaching
Haskell is really popular in universities and academia as a tool to teach programming. A lot of books for people who don't know programming are written around Haskell. This means that there are a lot of resources for beginners in programming with which to learn Haskell and functional programming concepts.
Pro Easy syntax for people with a STEM degree
Since the basic syntax is very similar to mathematics, Haskell syntax should be easy for people who have taken higher math courses since they would be used to the symbols used in maths.
Pro Powerful categorical abstractions
Makes categorical higher order abstractions easy to use and natural to the language.
Cons
Con Easy to make mistakes when declaring variables
When writing a function, if a programmer forgets to declare a variable, that variable will be declared at global scope. The code will seem to run fine at first, but if another function uses a variable with the same name, but fails to declare it, it will create subtle, incredibly difficult to find bugs.
Con Some concepts may not be applied to other "mainstream" programming languages
Lua features a prototye-based inheritance model. While this is also used by Javascript, it's not used by many other mainstream languages, and so some of the concepts learned while learning Lua won't be very applicable to other languages.
Another thing that makes Lua different from other programming languages, is the fact that Arrays start at 1 instead of 0. While helpful for beginners, it can complicate logic and make it very confusing when switching languages.
Con Batteries not included
Lua is so small mainly due to many of the components not being included in the core package. A lot of people need the functionality provided by the Lua module management system LuaRocks and libraries such as Penlight.
Con Language extensions lead to unfamiliar code
Haskell's language extensions, while making the language incredibly flexible for experienced users, makes a lot of code incredibly unfamiliar for beginners. Some pragmas, like NoMonomorphismRestriction, have effects that seem completely transparent in code, leading beginners to wonder why it's there. Others, like ViewPatterns, and particularly TemplateHaskell, create completely new syntax rules that render code incomprehensible to beginners expecting vanilla function application.
Con Difficult learning curve
Haskell lends itself well to powerful abstractions - the result is that even basic, commonly used libraries, while easy to use, are implemened using a vocabularly that requires a lot of backround in abstract mathematics to understand. Even a concept as simple as "combine A and B" is often, both in code and in tutorials, described in terms of confusing and discouraging terms like "monad", "magma", "monoid", "groupoid", and "ring". This also occasionally bears its ugly head in the form of complicated error messages from type inference.
Con Package manager is unstable & lacking features
Cabal (There are other choices but this is the most popular) can not uninstall a package. Also working at a few locations it is difficult to have the same environment for each one be the same.
Con You have to learn more than just FP
Haskell is not only a functional language but also a lazy, and statically typed one. Not only that but it's almost necessary to learn about monads before you can do anything useful.
Con Symbols everywhere
Haskell allows users to define their own infix operators, even with their own precedence. The result is that some code is filled with foreign looking operators that are assumed to be special-case syntax. Even for programmers who know they're just functions, operators that change infix precedence can potentially break expectations of how an expression is evaluated, if not used with care.
Con Obscure ugly notation
0 = 1
Using "=" like this: <code>
-- Using recursion (with pattern matching)
factorial 0 = 1
factorial n = n * factorial (n - 1) </code> Example from https://en.wikipedia.org/wiki/Haskell_(programming_language)
is quite simply annoying aesthetics.
Con Documentation for most packages is short and lacking
A few Haskell packages are well documented but this is the exception, not the rule.
Most of the time a list of function signatures is what passes for documentation.
Con Too academic, hard to find "real world" code examples
Con You need some time to start seeing results
Haskell's static typing, while helpful when building a project, can be positively frustrating for beginners. Quick feedback for errors means delaying the dopamine hit of code actually running. While in some languages, a beginner's first experience may be their code printing "Hello World" and then crashing, in Haskell, similar code would more likely be met with an incomprehensible type error.
Con Lazily evaluated
Haskell's lazy evaluation implies a level of indirection - you're not passing a value, you're passing a thunk. This is often difficult to grasp not just for beginners, but for experienced programmers coming from strictly evaluated languages. This also means that, since for many, strict evaluation is their first instinct, initial expectations of a function's performance and complexity are often broken.
Con Only pure functional programming
Not proper functional programming but a subset of the style called pure functional programming.