What is Haskell?

Haskell is a purely functional programming language that lets you write programs by describing what to compute rather than how to compute it. It emphasizes immutability, strong static typing, and lazy evaluation, making code concise and mathematically reliable.

Let's break it down

  • Purely functional: Every function always gives the same output for the same input and doesn’t change any outside data.
  • Programming language: A set of rules and symbols we use to tell a computer what to do.
  • Describe what to compute: You focus on the relationships between data, not on step-by-step instructions.
  • Immutability: Once a value is created, it cannot be changed.
  • Strong static typing: The language checks the kinds of data you use before the program runs, catching many errors early.
  • Lazy evaluation: The computer only calculates values when they are actually needed, which can save work.

Why does it matter?

Because Haskell forces you to think about problems in a clear, mathematical way, it helps you write code that is easier to reason about, test, and maintain. Its strong type system catches bugs early, reducing costly runtime errors.

Where is it used?

  • Financial modeling: Banks and trading firms use Haskell for risk analysis and pricing engines where correctness is critical.
  • Compilers and language tools: Projects like the GHC compiler itself and the Elm front-end language are written in Haskell.
  • Data analysis pipelines: Companies leverage Haskell’s lazy streams to process large datasets efficiently.
  • Web services: Frameworks such as Yesod enable type-safe, high-performance web applications.

Good things about it

  • Very strong type system catches many bugs at compile time.
  • Pure functions make code easier to test and parallelize.
  • Lazy evaluation can improve performance by avoiding unnecessary work.
  • Concise syntax reduces boilerplate and improves readability.
  • Rich ecosystem of libraries for functional programming patterns.

Not-so-good things

  • Steeper learning curve for programmers used to imperative languages.
  • Smaller community and fewer job openings compared to mainstream languages like Java or Python.
  • Compile times can be long for large projects.
  • Interfacing with existing C/Java libraries sometimes requires extra effort.