Elm is a functional programming language that compiles to HTML, CSS, and Javascript. Its very Haskell-like syntax allows users to build complex event-based systems with an incredibly small amount of concise, readable code, as can be seen from the examples
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Question Ranking
Pros
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 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 High-level Functional-Reactive Code
Build animations, games, and interactions with an incredibly small amount of terse, readable code.
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 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 Growing community
Elm is gaining popularity, somewhat faster than many of the other solutions here. This translates to more code examples, more documentation, and more libraries.
Pro Good documentation
Elm is gaining popularity, somewhat faster than many of the other solutions here. This translates to more code examples, more documentation, and more libraries.
Pro Haskell-like modules
Elm uses easy to use Haskell-like 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 Interactive Programming and Hot Swapping
Support for hot swapping and interactive programming is included.
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 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.
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 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.
Cons
Con Poor tooling
There are editor plugins, but neither of them support basic features yet like
- navigate to referenced definition
- show expression type
Con Missing syntactic sugar ('where' clauses, pattern guards)
Elm is missing a lot of syntactic sugar that Haskellers may consider core, such as 'do' notation, 'where' clauses, pattern guards, and operator sections.
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 Not quite Haskell semantics
Elm is a strict language, semantically different from Haskell. Elm also borrows a lot from OCaml and F#. While this makes for a nice syntax, it does mean that, for the Haskell programmer, there may be some surprises when it comes to semantics or function names.
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 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.