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Question-1. What is Idris?
Answer-1: Idris is a functional programming language with dependent types, similar to Agda and Haskell.
Question-2. What are dependent types in Idris?
Answer-2: Dependent types allow types to be defined based on values, enabling strong compile-time verification.
Question-3. What is the file extension for Idris source files?
Answer-3: .idr
Question-4. How do you define a function in Idris?
Answer-4: f : Type; f = expression, e.g., add : Int -> Int -> Int; add x y = x + y.
Question-5. What is totality checking in Idris?
Answer-5: It ensures functions are well-defined and terminate for all inputs.
Question-6. What is an inductive data type in Idris?
Answer-6: A type defined by constructors, e.g., `data Nat = Z
Question-7. What is the purpose of data in Idris?
Answer-7: It defines algebraic data types, e.g., `data Bool = True
Question-8. How do you pattern match in Idris?
Answer-8: Using case expressions, e.g., not : Bool -> Bool; not True = False; not False = True.
Question-9. What is Set in Idris?
Answer-9: Set represents the universe of types, similar to Agda's Set.
Question-10. How do you define a dependent pair in Idris?
Answer-10: Using (x : A ** B x), which is similar to Sigma types.
Question-11. How does Idris ensure correctness of programs?
Answer-11: By using dependent types to encode constraints in types.
Question-12. How do you define a record in Idris?
Answer-12: Using record Name where field fieldName : Type.
Question-13. What is interface in Idris?
Answer-13: It defines type classes, e.g., interface Eq a where (==) : a -> a -> Bool.
Question-14. What are implicit arguments in Idris?
Answer-14: Arguments enclosed in curly braces {} that are inferred automatically.
Question-15. What is a theorem in Idris?
Answer-15: A function that proves a property using dependent types.
Question-16. How do you define an indexed data type in Idris?
Answer-16: Using type parameters, e.g., `data Vec : Type -> Nat -> Type where Nil : Vec a Z
Question-17. What is an equality type in Idris?
Answer-17: x === y represents equality proofs.
Question-18. How do you prove equality in Idris?
Answer-18: Using Refl : x === x.
Question-19. What is auto in Idris?
Answer-19: A keyword that allows automatic solving of constraints.
Question-20. How do you handle interactive proofs in Idris?
Answer-20: Using the Idris REPL and interactive proof tactics.
Question-21. What is believe_me in Idris?
Answer-21: It is an unsafe escape hatch for type-checking, bypassing type safety.
Question-22. How does Idris handle side effects?
Answer-22: Using monads, such as IO for input/output operations.
Question-23. What is a pi type in Idris?
Answer-23: A dependent function type, written as (x : A) -> B x.
Question-24. How do you define an infinite data structure in Idris?
Answer-24: Using coinductive types or laziness with Stream.
Question-25. What is do notation in Idris?
Answer-25: A syntax for sequencing monadic computations, similar to Haskell.
Question-26. How do you define a polymorphic function in Idris?
Answer-26: Using type variables, e.g., id : a -> a; id x = x.
Question-27. What is a where clause in Idris?
Answer-27: It defines local helper functions, e.g., f x = y where y = x + 1.
Question-28. How do you define a higher-order function in Idris?
Answer-28: By passing functions as arguments, e.g., map : (a -> b) -> List a -> List b.
Question-29. What is Total in Idris?
Answer-29: It enforces that functions terminate and cover all cases.
Question-30. What is partial in Idris?
Answer-30: It allows defining non-total functions without termination proof.
Question-31. How do you work with lists in Idris?
Answer-31: Using `data List a = Nil
Question-32. What is Dec in Idris?
Answer-32: A type for decidable propositions, allowing proof checking.
Question-33. How do you define a monad in Idris?
Answer-33: Using interface Monad m where (>>=) : m a -> (a -> m b) -> m b.
Question-34. What is cong in Idris?
Answer-34: A function that applies equality proofs to functions.
Question-35. What is rewrite in Idris?
Answer-35: It is used in proofs to substitute equal terms.
Question-36. What is induction in Idris?
Answer-36: A proof technique using recursive pattern matching on data types.
Question-37. How do you enable dependent type checking in Idris?
Answer-37: It is enabled by default as part of the language.
Question-38. What is void in Idris?
Answer-38: A type that has no values, used to indicate impossible cases.
Question-39. How do you define a functor in Idris?
Answer-39: Using interface Functor f where map : (a -> b) -> f a -> f b.
Question-40. Can Idris compile to executable programs?
Answer-40: Yes, Idris can compile to C, JavaScript, and other backends.
Question-41. What is intros in Idris proof mode?
Answer-41: It introduces variables into a proof context.
Question-42. How do you define a custom operator in Idris?
Answer-42: Using (operator) : Type; (operator) x y = expression.
Question-43. What is hole in Idris?
Answer-43: A placeholder (?name) used to generate type suggestions in the REPL.
Question-44. How do you optimize Idris programs?
Answer-44: Using total functions, avoiding excessive dependent types, and enabling optimizations.
Question-45. What are homotopy types in Idris?
Answer-45: Higher-dimensional types used in homotopy type theory (HoTT).
Question-46. How do you prove a property about lists in Idris?
Answer-46: Using induction on list structure.
Question-47. What is a Nat in Idris?
Answer-47: A type representing natural numbers, defined as `data Nat = Z
Question-48. How do you install Idris?
Answer-48: Using apt-get install idris (Linux) or brew install idris (Mac).
Question-49. How do you run an Idris program?
Answer-49: Using idris filename.idr -o output && ./output.
Question-50. Where can you learn more about Idris?
Answer-50: The official site: https://www.idris-lang.org.
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