Scheme Interview Questions and Answers for 10 years experience

1. What is the difference between `define` and `lambda` in Scheme?

   • Answer: `define` creates a named procedure, binding a name to a piece of code. `lambda` creates an anonymous procedure, a function without a name that can be passed around or used immediately. `define` is for top-level definitions, while `lambda` allows for creating functions within other functions or expressions.

2. Explain tail recursion and its importance in Scheme.

   • Answer: Tail recursion occurs when a recursive call is the very last operation performed in a function. Scheme interpreters can optimize tail-recursive functions to avoid stack overflow errors, essentially turning recursion into iteration. This is crucial for handling large recursive computations efficiently.

3. How does Scheme handle lists? Describe common list operations.

   • Answer: Scheme represents lists as linked lists. Common operations include `car` (returns the first element), `cdr` (returns the rest of the list), `cons` (adds an element to the beginning), `append` (concatenates lists), `map` (applies a function to each element), `filter` (selects elements based on a predicate), and `fold` (accumulates a result from the list).

4. Describe the concept of continuations in Scheme.

   • Answer: Continuations represent the rest of the computation that needs to be performed after a particular point in the program. They capture the execution context, allowing for non-local control flow and features like exceptions and coroutines. Scheme's ability to manipulate continuations directly is a powerful, though potentially complex, feature.

5. Explain the difference between `eq?`, `eqv?`, and `equal?`.

   • Answer: `eq?` checks for object identity (whether two variables point to the same memory location). `eqv?` checks for equality of simple data types (numbers, characters, symbols) and checks for object identity for other objects. `equal?` performs a deep comparison, checking for structural equality of complex data structures like lists.

6. How would you implement a factorial function in Scheme using iteration and recursion?

   • Answer: Iterative: (define (factorial-iter n) (let loop ([n n] [acc 1]) (if (= n 0) acc (loop (- n 1) (* n acc))))) Recursive: (define (factorial-rec n) (if (= n 0) 1 (* n (factorial-rec (- n 1)))))

7. What are macros in Scheme, and how are they useful?

   • Answer: Macros are code transformers. They take code as input and produce modified code as output, extending the language's syntax. They're useful for creating domain-specific languages (DSLs) within Scheme, improving code readability, and implementing new control structures or syntactic sugar.

8. Explain the concept of higher-order functions in Scheme and provide examples.

   • Answer: Higher-order functions are functions that take other functions as arguments or return functions as results. Examples include `map`, `filter`, and `fold`, which all operate on functions and data.

9. How would you implement a function to flatten a nested list in Scheme?

   • Answer: (define (flatten lst) (cond ((null? lst) '()) ((pair? (car lst)) (append (flatten (car lst)) (flatten (cdr lst)))) (else (cons (car lst) (flatten (cdr lst))))))

Thank you for reading our blog post on 'Scheme Interview Questions and Answers for 10 years experience'.We hope you found it informative and useful.Stay tuned for more insightful content!