When comparing C# vs Elm, the Slant community recommends C# for most people. In the question“What is the best programming language to learn first?” C# is ranked 7th while Elm is ranked 13th. The most important reason people chose C# is:
C# runs on top of the .NET framework, which provides many libraries containing classes used for common tasks such as connecting to the Internet, displaying a window or editing files. Unlike many other languages, you don't have to pick between a handful of libraries for every small task you want to do.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro .NET is a great toolbox
C# runs on top of the .NET framework, which provides many libraries containing classes used for common tasks such as connecting to the Internet, displaying a window or editing files. Unlike many other languages, you don't have to pick between a handful of libraries for every small task you want to do.
Pro Incredibly Well-Engineered Language
Where other languages invoke the feeling of being a product of organic growth over time, C# just feels like an incredibly well-designed language where everything has its purpose and almost nothing is non-essential.
Pro Awesome IDE for Windows
On Windows, Visual Studio is the recommended C# IDE. It provides a very flexible GUI that you can rearrange the way you want and many useful features such as refactorings (rename a variable, extract some code into a method, ...) and code formatting (you can pick exactly how you want the code to be formatted).
Visual Studio also highlights your errors when you compile, making your debug sessions more efficient since you don't have to run the code to see the mistakes. There's also a powerful debugger that allows you to execute the code step-by-step and even change what part of the code will be executed next. In addition to giving you all the line-by-line information you'll need in a hassle-free manner, Visual Studio has stuff you can click on in the errors window that will take you to the documentation for that error, saving you several minutes of web searching.
In addition to all of this, Visual Studio has an intuitive, intelligent, and helpful graphical user interface designer that generates code for you (the best of WYSIWYG, in my opinion), which is helpful for new programmers. Being able to create a fantastic-looking UI with one's mouse and then optionally tweak with code helps make programming fun for beginner developers.
Visual Studio also has the best code completion --Intellisense is every bit as intelligent as the name says it is. It, as well as VS's parameter hinting, is context-, type-, user-, and position-sensitive, and displays relevant completions in a perfectly convenient yet understandable order. This feature allows a new programmer to answer the questions "What does this do?" and "How do I use it?" right then and there rather than having to switch to a browser to read through extensive documentation. This allows the programmer to satisfy their curiosity before it is snuffed out by several minutes of struggling through exhaustive documentation.
And for the more adventurous and text-ready developer, Microsoft does the best job of ensuring that everything, from interfaces and wildcard types down to Console.WriteLine("") and the + operator, is well-documented and easy to understand, with relevant and well-explained usage examples that manage to be bite-size yet complete, simple yet truly helpful. The reference site is easy to navigate, well-organized, clean and uncluttered, up-to-date, and fresh and enjoyable to look at, and every page is well-written with consideration for readers who are not C# experts yet want to read about changing the console background color.
The best part? It's free! Visual C# Express contains all of the features described above, at zero cost. If you are a student, you can probably get Visual Studio Professional from your university, which also includes tools for unit testing and supports plugins.
Pro Supports some functional features
C# is primarily object-oriented, but it also supports some features typically found in functional languages such as lambdas, delegates and anonymous classes. Methods can be treated like any other object, and the Linq query system operates on monads with lazy evaluation (though it hides this with a lot of syntactic sugar).
You don't need to use these features to code in C#, though, so you can start with OOP and then learn about them.
Pro Great introduction to object-oriented programming
Object-oriented programming is the most widely-used paradigm. C# offers support for common OOP features such as classes, methods and fields, plus some features not found in competing languages like properties, events and static classes.
C# code is much more readable thanks to the syntactic sugar it offers. You can truly concentrate on your code, not on the way it's implemented.
Pro Best language for Windows programs
C# is clearly the best choice for Windows programs. The .NET framework contains everything you need to build great-looking apps, without having to learn the confusing Win32 API or download a ton of external libraries. C# can also be used to build Windows 8's "modern" apps.
Pro Very high demand in the industry
C#'s been around for just the right amount of time, is regularly updated with useful additions, is versatile, easy to write & read, & has excellent tooling support. This means it is a top choice for many organizations & will remain so for the foreseeable future.
Pro Can mix high and low level programming
You can code at the high level without worrying about pointers and memory management, but if you so choose you can switch to lower level programming with direct memory management and pointer manipulation (though you need to compile to specifically allow this).
Pro Awesome IDE for cross-platform development
Visual studio has embraced cross platform development over the past 3 years. With Visual Studio Code, you now have a light, and quick IDE variant available for free as well.
Pro With ASP CORE a good language to learn
With CORE you are no longer just limited to Windows, so a language worth learning.
Pro Supported on many platforms
C# can be used for Windows apps, Linux apps, OS X apps, Windows 8 "modern" apps, websites, games, iPhone apps, Android apps, Windows Phone apps, and more.
If you want to create a cross-platform application, you can share most of the code and write one GUI for each platform.
Pro .NET truly universal
With .NET core it is a truly universal programming language which support desktop apps (Windows), Mobile apps (Xamarin), Web Apps (ASP.Core MVC). Also is perfectly fit to serverless programming for micro services. Soon it will be also support Web assembly (Blazor).
Pro Great language for Unity game engine
Unity provides a selection of programming languages depending on preference or knowledge - C#, JS, Boo and UnityScript. C# is arguably the most powerful with better syntax and stronger language structure. It allows using script files without attaching them to any game object (classes, methods inside unattached scripts that can be used at any time). There are more tutorials and information for C# than UnityScript and Visual Studio can be used to code for unity in C#. Additionally, learning C# allows using it outside of Unity as well unlike UnityScript.
Pro No run-time exceptions
Lack of run-time exceptions makes it easy to produce large swathes of reliable front-end code without drowning in tests.
Pro Inferred static typing
ML static typing is great because it's always there, you just choose how explicit you want to be and how much you want the compiler to do.
Pro Super easy refactoring with very helpful compiler errors
In no other language you can refactor so easy without any worries, since the compiler will guide you through. It is like TDD but than compiler-error driven.
Pro Designed around high-level front-end development
As Elm was designed as a front-end langauge, it has out of the box support for things like DOM-element creation, letting programmers focus on their application logic, rather than implementation details specific to the web.
Pro Great and simple way to learn Purely Functional Programming
You can try to apply some functional programming ideas in other languages that have an imperative basis, but you haven't seen the real power unless you tried it in the environment of purely functional programming. Elm is a simple language with great learning resources and easy graphical output, which makes it easy to explore the power of functional programming. Plus programming in Elm is very readable.
Pro Good tooling
All major editors have great support. With Atom for example, Elm plugins are available for linting, formatting, make/compiler support and Elmjutsu will simply overflow you with super useful functions, like navigate to referenced definition and show expression type.
Pro Batteries included
The Elm Architecture means you don't need to spend valuable time and effort choosing the right frameworks, state management libraries, or build tooling. It's all built in.
Pro Static module system
Elm uses easy to use modules.
Use:
import List
import List as L
import List exposing (..)
import List exposing ( map, foldl )
import Maybe exposing ( Maybe )
import Maybe exposing ( Maybe(..) )
import Maybe exposing ( Maybe(Just) )
Creation:
module MyModule exposing (foo, bar)
Pro Missing syntactic sugar
Easy to learn, most functions have only one way, not 5 alternatives where you must study where to best use what.
Pro Growing community
Pro Interactive Programming and Hot Swapping
Support for hot swapping and interactive programming is included.
Pro Easy to code review
The lack of side-effects and simple, consistent language semantics make it easy to quickly review incoming changes.
Pro Higher confidence in code correctness and quality
Pure functions, immutable data structures, amazing compiler, clean and homologous syntax used for HTML, logic, and optionally to replace CSS, elimination of entire classes of bugs so you don't even need most unit tests. These factors lead to better code, better programs, higher confidence, and ultimately, more satisfaction.
Pro Not quite Haskell semantics
Luckily you do not have to learn Haskell to be able to do any Elm. It is meant to be a language that compiles to Javascript, so for Javascript programmers (Front end) not for CS students who want to learn as many different algorithms as possible.
Cons
Con Older versions lacks standard-library support for immutable data structures
Con Complex syntax
Too many syntactic constructs to learn before it becomes usable.
Con .NET is a mess
Continual drama with standards, updates, Microsoft, and being really cross-platform.
Con Excessively class based OOP oriented
Limits users into overly using awkward paradigm and creating another kind of spaghetti code.
Con A pale imitation of Java
C# is a Java-like language, but Microsoft failed to imitate Java's consistency. For instance, C# has types that cannot be passed by address (e.g. DateTime), forcing the developer to use ugly workarounds.
Con Too easy to write multithreading apps that are buggy
Many web frameworks or GUI libraries will push novice users to writing multithreaded code, which leads to frustrating race condition bugs.
Other languages with multithreading push users towards safe constructs, like passing messages and immutable or synchronized containers. But in C# the data structures aren't synchronized by default, and it's too easy to just set a field and observe the result from another thread (until you compile with Release, and now you have a heisenbug).
Con Often-used products in most C# development environments get expensive
The majority of the C# development community uses Microsoft products which are not all free and open-source. As you get into the enterprise level of some of these products and subscriptions, the expense is multiple factors of 10 greater.
While you can use a fully open-source and free C# environment, the community around that is much smaller. While this can be said for other languages as well, the majority of C# falls into the for-pay Microsoft realm.
Con Popularly used on Visual Studio (proprietary)
Most people learn and depend on Visual Studio (proprietary) to write C#. The result is people learn how to use an IDE and not the concepts or fundamentals of good programming. However, you don't need VS to develop in C#, all you need is the dotnet CLI and a text editor that supports OmniSharp like VSCodium, Vim and Emacs.
Con Large Library and eco system makes it unsuitable for beginers
yes, all the information about the .net framework is in one place, but it is so extense that it introduces a steep learning curve for newcomers to the field of programming languages.
Con Lack of typeclasses
Elm doesn't have typeclasses which means some code needs to be duplicated. A fix in a function that needs typeclasses means all of the duplicates need to be fixed too.
Con limited js interop
only one way ports are available as a crude js FFI. This means you can only call functions both directions but will not get a result.
Con Harder to get buy-in from devs and mgmt
It's a total divergence from what most people are used to in the JS ecosystem. The change in syntax can be scary, the change in approaching problems can be scary. The fact that it's not backed by FANG can be scary. The fact that it's not v1.0 can be scary. The governance model and the deliberately slow release cadence can be scary. There are a couple harsh medium articles, hackernews/reddit posts out there made by people with an ax to grind that can be scary if you don't have a better picture of the Elm community, the tradeoffs that have been made, or the benefits to be had over other options. None of these are good reasons to write off further investigation of a great tech, but it happens.
Con Code Repetition
Because of the lack of genericness Elm needs a lot of code to be repeated. There are 130+ implementations of map in elms core libraries.
Con Features get removed without warning
Often features that are deemed to be misused by the community like infix operators get removed without much of a warning.
Con Community harsh if criticised
If one even dares to start a discussion about a feature on elms slack, discord, subreddit or github one will be aggressively shut down often argueing that one should use purescript instead
Con Poor Windows support
Few if any of Elm's core contributors are Windows users and breaking bugs are sometimes left for weeks or months.
Con Good for beginners not good for experts
Development in elm is quite nice until you need some more advanced features. These however are actively discontinued and removed because elm wants to establish a "single way of doing things" philosophy
Con Updates break existing code often
The last few updates of elm broke existing code in major ways.
Con Adds an additional layer of abstraction
Some users claim that Elm adds an additional layer of abstraction, meaning that it is one more hurdle between the brain and the product.
Con Functional programming itself has quite a steep learning curve
Functional programming can be quite difficult to get your head around. It takes time to unlearn object orientational habits.
Con No Genericness in the future
Currently there is no code genericness like typeclasses possible, it has been officially stated that this will never change.
Con Not database-friendly
It is lots of work to make a server or database your "one source of truth", as Elm makes you write endless JSON parse boilerplate to talk to the server.
Con No Syntactic Sugar
Often you need to write longer and less readable code because there are no alternatives that are more concise.