Haskell Questions and Answers for Viva

Answer-1: Haskell is a statically-typed, purely functional programming language named after the logician Haskell Curry.

Answer-2: Haskell was developed by a committee of researchers in the late 1980s.

Answer-3: Key features include lazy evaluation, type inference, immutability, and strong static typing.

Answer-4: Lazy evaluation delays computation until the result is actually needed.

Answer-5: In Haskell, functions have no side effects and always produce the same output for the same input.

Answer-6: A monad is a design pattern that encapsulates computations, chaining operations while managing side effects.

Answer-7: The IO monad is used to handle input/output operations in a purely functional way.

Answer-8: Type inference allows Haskell to automatically deduce types without requiring explicit annotations.

Answer-9: A higher-order function is a function that takes other functions as arguments or returns a function.

Answer-10: Algebraic data types are types formed by combining other types using data and constructors.

Answer-11: A type class defines a set of functions that can be implemented for different types.

Answer-12: = is used for defining values, while == checks equality of values.

Answer-13: A lambda function is an anonymous function written using the syntax \x -> x + 1.

Answer-14: Pattern matching is a way to decompose data structures by matching patterns in function definitions.

Answer-15: Guards are boolean expressions used to choose between function definitions or code branches.

Answer-16: A list is a collection of elements of the same type, defined using square brackets. Example: [1, 2, 3].

Answer-17: Use the ++ operator. Example: [1, 2] ++ [3, 4].

Answer-18: A tuple is a collection of fixed-size, ordered elements that can have different types. Example: (1, "Haskell").

Answer-19: Maybe is used to represent optional values. It can be Just value or Nothing.

Answer-20: Either represents two possible values: Left for errors and Right for successful results.

Answer-21: Recursion is a technique where a function calls itself to solve smaller instances of a problem.

Answer-22: List comprehensions provide a concise way to generate lists using an expression and filters.

Answer-23: Use the syntax functionName arguments = expression. Example: add x y = x + y.

Answer-24: let defines local bindings within an expression. Example: let x = 5 in x + 1.

Answer-25: where defines local bindings after an expression. Example: add x y = result where result = x + y.

Answer-26: Currying transforms a function with multiple arguments into a series of functions each with one argument.

Answer-27: Infinite lists are lazily evaluated lists that can generate values indefinitely. Example: [1..].

Answer-28: A fold reduces a list to a single value by applying a binary function. Example: foldr (+) 0 [1, 2, 3].

Answer-29: foldr folds a list from the right, while foldl folds it from the left.

Answer-30: map applies a function to each element of a list. Example: map (+1) [1, 2, 3].

Answer-31: filter selects elements of a list that satisfy a predicate. Example: filter even [1, 2, 3].

Answer-32: seq forces evaluation of its first argument before returning the second.

Answer-33: do notation simplifies chaining monadic operations in a readable syntax.

Answer-34: A pure function's output depends only on its input and has no side effects.

Answer-35: GHC stands for Glasgow Haskell Compiler, the most widely used Haskell compiler.

Answer-36: The $ operator is used to avoid parentheses, applying functions with lower precedence.

Answer-37: A thunk is a deferred computation created by lazy evaluation.

Answer-38: Use Either, Maybe, or the Control.Exception module for structured error handling.

Answer-39: >> sequences monadic actions, while >>= also passes the result to the next action.

Answer-40: A functor is a type class that applies a function to a wrapped value.

Answer-41: An applicative functor allows applying functions wrapped in a context to values in a context.

Answer-42: Type synonyms give existing types a new name using the type keyword. Example: type String = [Char].

Answer-43: newtype creates a distinct type from an existing one with zero runtime overhead.

Answer-44: MonadPlus is a type class for monads that support choice and failure.

Answer-45: The deriving clause automatically generates type class instances for a data type.

Answer-46: Lazy patterns allow deferred evaluation of pattern matches using ~.

Answer-47: Enum defines sequentially ordered types that can be enumerated.

Answer-48: Data.List is a module providing functions for list manipulation.

Answer-49: span splits a list while a condition is true, while break splits when the condition becomes true.

Answer-50: Combinators are higher-order functions that operate on functions to build complex behavior.