When comparing TypeScript vs Haskell, the Slant community recommends TypeScript for most people. In the question“What is the best programming language to learn first?” TypeScript is ranked 6th while Haskell is ranked 26th. The most important reason people chose TypeScript is:
Typescript has optional static typing with support for interfaces and generics, and intelligent type inference. It makes refactoring large codebases a breeze, and provides many more safeguards for creating stable code.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Optional static typing
Typescript has optional static typing with support for interfaces and generics, and intelligent type inference.
It makes refactoring large codebases a breeze, and provides many more safeguards for creating stable code.
Pro Strong typed language
Lot of benefits of it, you can read this.
Pro Strict superset of Javascript
Every existing Javascript program is already a valid TypeScript program giving it the best support for existing libraries, which is particularly useful if you need to integrate with an existing Javascript code base.
Pro First party Visual Studio support
As a Microsoft developed project, it has first party Visual Studio support that's on par with its C# support with features like syntax sensitive statement completion.
Pro Has a repository of high quality TypeScript type definitions for popular libraries
There are many ready to use and high quality TypeScript definitions for popular libraries including jquery, angular, bootstrap, d3, lodash and many-many more.
Pro Adds support for object-oriented programming
Typescript enables familiar object-oriented programming patterns: classes, inheritance, public/private methods and properties, et cetera.
Pro Polyfill for ES6 fat-arrow syntax
Typescript implements the fat arrow syntax, which always maintains the current context for this
and is a shorter/more convenient syntax than traditional function definition.
Pro Great support for React, integrated typed JSX parsing
Strongly typed react components, so UI "templating" automatically gains type safety.
Pro Great support for editors (Sublime, Code, Vim, IntelliJ...)
Pro Works well with existing Javascript code
Both can call Javascript code and be called by Javascript code. Making transitioning to the language very easy.
Pro Compiles to very native looking code
Compiles to simple looking Javascript making it easy to understand what is happening and learn the language (if you already know Javascript).
Pro Built and supported by Microsoft
Being built by Microsoft, TypeScript is much more likely than most other similar open-source projects to receive continued long-term support, good documentation, and a steady stream of development.
Pro Ability to do functional programming
Pro Clear roadmap
TypeScript has a clear and defined roadmap with rapid and constant releases.
Pro Low number of logical errors brought in by built-in type annotations
TypeScript's built-in type signatures allow developers to fully document interfaces and make sure that they will be correctly compiled. Therefore, cutting down on logical errors.
Pro Works well with Angular 2
Angular 2 is built using TypeScript and applications built using it can make use of that (or not).
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 Too similar to Javascript
Presents some advantages compared to Javascript, but because it is designed to be a superset of Javascript, it means all the bad parts of Javascript are still present.
Con Type checking not enforced by default
You have to use compiler flags to make sure it catches flaws like usage of implicit any, etc.
Con Type inference coverage is incomplete
The default type when declaring and using a variable is any
. For example, the following should break but does not:
function add(a:number) { return a + 1 }
function addAB(a, b) {return add(a) + b}
addAB("this should break but doesn't :(", 100)
In order to avoid this, you have to declare type signatures for every variable or parameter or set the flag --noImplicityAny
when running the compiler.
Con Requires "this" for field access
Even in cases were there is no ambiguity, you still have to use "this.fieldName" instead of just "fieldName".
Con Syntax is too verbose
Con No support for dead code elimination
Typescript compiler does not remove dead code from generated file(s), you have to use external tools to remove unused code after compilation. This is harder to achieve, because Typescript compiler eliminated all type information.
Con No support for conditional compilation
There is no clean way to have debug and release builds compiled from the same source, where the release version removes all debugging tools and outputs from the generated file(s).
Con Awful error messages
Comparing to Elm or Rust for example, TypeScript's error messages won't say you very much. For example if you change method of interface which your class implements it won't say your class have incorrect implementation. Instead it'll show error in usage of instances of class. In some cases it can spoil hours of your work trying to figure out why your parameters are incorrect.
Con Technical debt
As consequence of not enforcing type checking.
Con No Java-like package structure
If you prefer a Java-like approach of partitioning your code into different packages, the module system of typescript will confuse you.
Con Small community
Con No option to declare that a function throws errors
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.
Con Curried type signatures obfuscate what were the in and out types originally
