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Hire only the best haskell developers among the 20K+ engineers who have applied to UltraGenius


Freelance Haskell Developer

Rishabh is a software engineer having 7+ years of experience in software development using Haskell programming language. He is an expert in functional programming and researches.

Expert in


Core Java




10 Years


Full Time


Haskell Freelance Developer

Mahesh is a software engineer having 3+ years of experience developing software applications using Haskell programming language. He is also expertise using Javascript.

Expert in






10 Years


Full Time


Part-time Haskell Freelancer

John is a software engineer having 10+ years of experience in software development using Haskell programming language. He is an expert in functional programming and researches.

Expert in






10 Years


Full Time

Hire top talented Haskell freelance developers with UltraGenius

Haskell is a general purpose functional programming language used for mathematical computation and researches. Haskell helps freelance Haskell developers to deliver high performance and quality software to use.

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Developers' Reviews for UltraGenius

UltraGenius offers a great opportunity to work in mission-driven U.S. companies with a great salary. I am glad that I chose UltraGenius to find my dream job.
Jason Martin
Senior Haskell Freelance Developer
Once you are part of UltraGenius, you don't have to look for another platform which leads you to your dream job. UltraGenius's vetting tests and assessments are unmatchable and helped me a land an excellent job.
Barbara Smith
Freelance Haskell Developer
I will thank to UltraGenius wholeheartedly. It helped me securing a career-growing high paid job which I couldn't think would be possible for me without this top connecting network.
Mark Sommers
Part-time Haskell Developer

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Want to hire freelance Haskell developers on your own? Here are the skills you must look for while hiring a freelance Haskell developer

Hiring freelance Haskell developers might be an intricate task for you if you are a non-technical manager. Haskell is one of the well known languages used for research purposes and implementing functional programming in applications, and hiring the most skilled freelance Haskell developers among thousands of developers is a challenging task for anyone. So, UltraGenius is here to assist you while recruiting the top talented freelance Haskell developers on your own. UltraGenius understands your job requirements and gets you only the top developers who have in-depth knowledge of software development.

The following skills you must look for while hiring a freelance Haskell developer –¬†

Steadfast knowldege of HTML and CSS

Knowledge of HTML (Hypertext Markup Language) and CSS (Cascading Style Sheets) is very important for a freelance Haskell developer. You must hire such a Haskell freelance developer who has practiced and worked deeply with these technologies. Knowledge of Flexbox and CSS Grid, in addition to Bootstrap, Semantic and Structural Styling, and Foundation is a must to a freelance Haskell developer. Along with this, the freelance Haskell developer should be well-versed in Javascript libraries especially jQuery and CSS grid systems. 

Javascript fundamentals + ES6

Javascript is most widely used language in developing dynamic web applications and helps freelance Haskell developers integrate back-end with the front-end easily. The Haskell freelance¬†developer¬†must be clear with the fundamental concepts of Javascript language. ECMAScript 6 (or ES6) is the current version of ECMAScript and is widely used by developers up to a large extent. The¬†freelance LAMP developers must be familiar with these ES6 skills ‚Äst¬†

  • Arrow functions
  • Blocked scope constructors let and const
  • Advanced object literals
  • Template literals
  • Multi-line strings
  • Modules
  • Module loaders
  • Binary and octal literals
  • Reflect API
  • Proxies
  • Classes
  • Destructuring assignment
CSS Pre-processors and Frameworks

A CSS pre-processor is a program that extends the functionality of CSS and compiles it into regular CSS. SASS, PostCSS, SCSS, and LESS are the extensions of regular CSS and developers use them for useful functions such as math functions, color manipulation, to write better inline documentation, to easily integrate CSS tools and CSS codebase, and much more. It makes developers write lines of code in very less time because of its in-built functionalities.

You must check the¬†freelance Haskell developer’s knowledge of Bootstrap and Material UI, as these components streamlines the development process and ensures that a web application looks best.

Knowledge of Haskell libraries

Haskell libraries helps a Haskell freelance developer while Haskell development. Check if the freelance Haskell developer knows about these popular libraries Рvect, vector, binary, Hascore, attoparsec, aeson, stringsearch, moo, and text. Other most frequently used libraries include conduit, functional graph library, graph automorphism library, streams, arrays and references library, edison, Yesod, http-client, Pointless Haskell, GenUtil, hspec, and many more.

Experienced in working with Version Control System (VCS)

Freelance Haskell developers must possess very good knowledge of version control systems, like Git, SVN, TFS, and Mercurial. Mostly, developers use Git for their work. It is the version control system that helps the team in collaborating and organizing your code, maintain the frequent changes that occur in the code. Git helps in reviewing the old codes and compares them with the newly updated code, pulling the code from their repository, and managing the commit history.

Along with this, the Haskell freelance developers developer must know how to use add, push, pull, and commit commands, branching, and merging as it allows developers to work independently on the code.

Excellent understanding of testing frameworks and tools

Rising quick-deployment needs during the development phase, testing has become the most demanding skills for a freelance Haskell developer. Therefore, freelance Haskell developers must have knowledge of Jest, Enzyme, Mocha, Chai, AVA, and Tape for unit testing. For end-to-end testing, they must know about Selenium, Webdriver, Cucumber.js, Nightwatch.js, Cypress, and Puppeteer. For integration testing, they must know about Karma.

Good grasping on functional programming

Functional programming is a paradigm of building software by composing pure functions without mutating state and data. Functional Programming enhances the productivity of the program. It provides immutable data structures that are not faced with race conditions and¬† thereby employs safe multi-threading. Functional programming comes under the ‚ÄúDeclarative Paradigm‚ÄĚ in which the program logic is written without explicitly describing the flow control.

Knowledge of front end technologies like React or Angular

Freelance Haskell developers must know about front end technologies and frameworks particularly React.js or Angular.js. These front-end frameworks are greatly required in today’s market. React is popular for its faster development of Single Page Applications while Angular uses interpolation, dependency injection, and eliminates coding mistakes by using the strongly typed Typescript that resolves many challenges faced by the developers.

Ability to cross browser compatible code

You must hire the freelance Haskell developers based on their ability to write cross browser platform compatible code. With cross-browser compatibility, your website will have an increasing traffic and it will deliver the best user driven experience, independent of the browser on which it is running on.

Well versed using Lambda expressions

Haskell’s core feature is functional programming and lambda expressions. Lambda expressions provide one line concise syntax for writing functions. These functions are not named and hence cannot be called but they can be passed as parameters to higher order functions such as map, reduce, sort, zip, and forEach are some examples of higher order functions.

Practical experience implementing higher order functions

Haskell uses higher order functions which makes your code more abstract without affecting the internal functionality. A higher order function takes another function as an argument and returns the output in the form of a function. Higher order functions make the code concise which improves its readability. Check if the Haskell freelance developers have implemented  map, sort, reduce, filter, and forEach functions and know their utility in programming.

Experience with web markup and UI, UX Concepts

The developer must have a firm understanding of element positioning, displaying the elements, and making components interactive, semantic markup, and other related UX Concepts so they can design the product with the best quality. The developer must be experienced in developing visual effects in presentational markup. For, example РHow the heading appears, making text larger and putting weight to it, and giving which color to it, and which markup can include captions, bind columns, and row headings to table cells. 

Knowledge of OO Programming

Haskell follows OO programming approach which makes every object in Haskell immutable. When you want to change the contents of any object, you have to make a replica (or copy) of that object and replace only the bits which needs to be changed.

Proficient in writing optimized and readable code

To streamline the development process,  the freelance Haskell developers must be proficient writing clean and high-performance optimized code that is understandable by all the team members.

Pay only after one week trial period

Connect with the top 1% freelance Haskell developers of the world at the lowest prices

Haskell is widely used functional programming language in dustries like hardware designing firms, web startups, and mostly for research and academia.  But recruiting the best freelance Haskell developers is not an easy task when a large no. of Haskell freelance developers are competing to grab the job opportunities.

Top Interview Questions to ask while hiring a freelance Haskell developer

Haskell is a functional programming language designed for mathematical computations and research purposes. Haskell has a wide range of usages from aerospace to finance and many popular web startups. Haskell is used by projects like Sigma, Barclay Bank's Functional Payout Framework, NASA 's Copilot Project, and so on.

Automatic Memory Management - Haskell provides automatic memory management technique which avoids memory leaks, buffer overflows, and other memory related issues in a program that are possible in C++/C programming languages.

Compiled directly to Machine code - Haskell programming language gets directly compiled to native machine code unlike Java, Python, C++ which needs an intermediate code which then compiles to native machine code.

Rich Esoteric Libraries  - 

Haskell has a large library which provides the freelance Haskell developer to work more efficiently and effectively. Some of the popularly used Haskell libraries are - Hascore, binary, vector, vect, aeson, bytestring, and attroparsec.

Static typing like Typescript - Haskell checks the code validity and bugs in the code at the compile time only which helps developers resolve issues at the static time only. 

Versatile Toolset - Haskell provides a wide range of versatile tools for statically typed code and support for type qualities, algebraic data types, runtime inspection, parametric polymorphism, kind polymorphism, ad-hoc (class-based) polymorphism, higher-rank polymorphism, and existential qualification.

Metaprogramming - Haskell provides support for the generation and inspection of the program's syntax tree. This metaprogramming feature is also known as Template Haskell. It is used for automatic boilerplate generation and compile-time evaluation.

Concurrency - Haskell provides the concept of Green Threads, which includes wonderful libraries like async and stm, which makes applications achieve concurrency. 

Hackage and Stackage - Haskell provides a large set of centralized repository which includes over 14000 featured packages called Hackage. To provide compatibility between libraries, it also has a collection known as Stackage, which has over 2000 well handled packages.



Higher order functions take another function as an argument like lamda expressions or returns the output in the form of a function. Freelance Haskell developers must be familiar with the functions like sort, map, reduce, forEach,and filter functions.

A lambda expression is a block of code that is passed as an argument to the higher order functions such as map, sort, reduce, forEach, and filter. Lambda expressions prevent developers write multiple lines of code and make the program look clean and concise. Lambda expressions can be stored in a variable also if the data type of that variable is an interface which contains only one method. However, the condition is that the lambda expression must have the same number of arguments with same data type and same return data type as that of the method in the interface. 

Immutable objects in Haskell are thread-safe and more secure. For example, if you want to modify array elements in Haskell, it will return you the new array with modifications. Only accessing elements is allowed in the original array. Mutable objects often have the aliasing problem associated with them which causes programming errors, but Haskell resolves this problem by making objects immutable and guarantees referential transparency. 

The $ operator is used to avoid parenthesis in the code. For example, in putStrLn(display(2+2)), you can write this line in the following ways as :

  • putStrLn $ display $ 2 + 2
  • putStrLn $ display (2+2)
  • putStrLn (display $ 2 + 2 ).

The . operator on the other hand is used to chain the functions instead of avoiding parenthesis. In the above example, you can chain display to putStrLn like this : 

(putStrLn . display)(2 + 2)

And if you want to avoid putting multiple parenthesis, just put $ operator like  :

putStrLn . display $ 2 + 2

A monad in Haskell is an abstract algebraic structure used to represent the computation as a series of steps. Monads provide a structure representing a program. There are three building blocks associated with Monad - 

  • A function that takes a value and¬† returns a computation which when executed generates that value.
  • A function which takes two computations and executes them one after another. The result of the first computation is made available to the other.
  • A type constructor that generates the type of a computation of you mention the type of the result of that computation.

Enum Type Class in Haskell provides the operations on data types in sequential order. The following commands can access the Enum Type Class - 

Succ - returns successor of a value.

Pred - returns the predecessor of that value.

Int, Char, Bool, Float, etc. can also access the Enum Type Class.



Data.Foldable.Foldr function converts an accumulator into a single value by applying the foldr function against it. For example, foldr(++) [][[10,20],[30,40],[50,60]] will return [10,20,30,40,50,60].

Ord class provides precise ordering two objects. Ord class has the following properties :-

  • Comparability -If¬† a<=b || b<=a , then True.
  • Transitivity - If a<=b && b<=c , then a<=c is Ture.
  • Antisymmetry - If a<=b && b<=a , then a==b is True.
  • Reflexivity -¬†If a<=a, then True.


Functor is an in-built higher order function which takes fmap() function as an argument and returns output as a function. fmap() function is the general representation of the map() function.

Map, List, Tree, etc.  are the instances of Functor. The function definition of Functor is given by - 

class Functor func where fmap :: (x -> y) - > func x -> func y.


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Frequently Asked Questions

UltraGenius is one of the leading platforms for hiring remote talent and connecting freelance and part-time developers with Silicon Valley businesses. We focus on finding the best talents who will perform extremely well and will be easily integrated into your teams. We filter out only the top 1% most skilled freelance developers among the 20K+ developers who have applied on our platform. Candidates have to prove their self-reported experience by giving Ultragenius’ s skill tests.

UltraGenius first tests the developer’s skill set by conducting a two and half hour hiring test. Our hiring test judges a candidate on all aspects like aptitude, case study analysis, verbal and reasoning, coding questions based on data structures and algorithms, software engineering, system design, and more. Then, there is another round for the candidates who are selected from this round called “Higher-level Assessment Skill Test‚ÄĚ, which is a video round that deeply analyzes Haskell freelance developers‚Äô major skills and asks questions about the projects they have worked upon.

Fill up the form which is on every hiring freelancers’ page and we will inform you once we select the top 1% freelance Haskell developers matching your job requirements.  After analyzing the candidates based on their resumes and two assessment tests, we provide you the feedback quickly. And if the freelancers selected by our team are fit for your job role, then we also provide the onboarding.

UltraGenius offers you only the most skilled freelance developers who are top 1% among the 20K+ freelance developers who have applied on our platform. After a rigorous selection and testing process, we sort out only the top candidates for you. You can check out UltraGenius’ s selection process for hiring freelance Haskell developers on https://www.ultragenius.club/hire-haskell-freelancer/.

UltraGenius provides you the best facility to hire freelancers in more than 50 skills like React, Angular, Javascript, Node, Java, Python, Magento, Ruby On Rails, Golang, PHP, WordPress, .NET, Android, iOS, DevOps, Machine Learning, and many more.


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