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Compile and run Haskell code online instantly with HCODX. Our free cloud-based Haskell compiler supports real-time execution, standard input, syntax highlighting, and code download. No installation or configuration required. Start coding in Haskell now.
Run Haskell instantly without installing any IDEs or configuring environments. Our cloud-based Haskell handles libraries, runtimes, and dependencies automatically so you can focus on writing code.
Whether you are studying algorithms in Haskell, practicing data structures in Haskell, or exploring functional programming, our tool provides real-time stdout/stderr feedback with interactive standard input support.
HCODX is a free online compiler and code runner: write code in your browser, execute it on a cloud sandbox, and interact with your program through a live terminal. Students use it for coursework and interview practice; developers use it to test snippets in 85+ languages without setting up a local environment.
Haskell is the reference point for pure functional programming — the language other languages cite when they add lambdas, algebraic data types, or type inference. Defined by committee in 1990 and compiled today by GHC (the 9.x series is current), it enforces purity: functions can't sneak in side effects, IO is tracked in the type system, and evaluation is lazy by default. That rigor made it the darling of programming-languages research and a fixture of university PL courses, while industry users like Standard Chartered, Meta (the Sigma anti-abuse system), and fintech firms run it in production. This page compiles and runs Haskell in a live terminal, where getLine reads your actual typed input — no GHC installation required.
import System.IO
fibs :: [Integer]
fibs = 0 : 1 : zipWith (+) fibs (tail fibs)
main :: IO ()
main = do
hSetBuffering stdout NoBuffering
putStr "What's your name? "
name <- getLine
putStrLn ("Hello, " ++ name ++ "!")
putStr "How many Fibonacci numbers? "
n <- readLn :: IO Int
print (take n fibs)
putStrLn ("The largest is " ++ show (fibs !! (n - 1)) ++ ".")Haskell is a rite of passage in programming-languages and functional programming courses at universities across the US, UK, and Australia — think folds, typeclasses, monads, and lazy infinite structures on problem sets. This page removes the classic first hurdle (installing GHC and cabal) so you can focus on the ideas: test a fold, check what type inference deduces, or step through a recursive definition. It's equally useful for interview prep at FP-friendly companies and for working through 'Learn You a Haskell' or CIS 194 exercises from any browser. HCODX is a free online Haskell editor, runner and interpreter — an IDE-grade compiler and playground to write and run code online, execute code with live output and live preview, no downloads or web server required.
Yes, getLine blocks until you type a line into the live terminal. If a putStr prompt seems delayed, that's GHC's output buffering — add hSetBuffering stdout NoBuffering (from System.IO) at the top of main, as the example does, and prompts flush to the screen immediately before input is read.
Yes — your file is compiled by GHC, the standard Haskell compiler, and then executed, so type errors surface exactly as they would locally and runtime behavior (laziness included) matches a native binary. It isn't a toy interpreter or a subset; language extensions supported by the installed GHC work via pragmas.
Only libraries bundled with the GHC installation are importable — base is always safe, and GHC ships with a few core libraries, but there is no cabal or stack to fetch Hackage packages. For coursework this rarely matters: Prelude, Data.List, Data.Char, and Control.Monad cover the standard exercises.
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