Haskell Practice (Basics)

Intuition

Learning through practice: Practice problems are like training drills — they help you apply knowledge and identify areas that need more study.

Why it matters: Regular practice builds confidence and reveals patterns in how concepts are tested. Each problem reinforces key programming concepts.

The key insight: Making mistakes during practice is valuable — each error points to a concept that needs clarification.

Haskell — Interactive Practice

10 auto-graded practice problems covering core Haskell concepts. Select an answer, submit, and review the explanation.

Types and Functions

Pattern Matching

Type Classes

Monads

Lazy Evaluation

Common Mistakes

Confusing = with ==: = is binding/definition; == is equality comparison from the Eq type class. Using = in a guard or condition causes a parse error.

Assuming ++ works on non-list types: ++ only concatenates lists. For other types like Seq or Vector, use their specific append functions. Type errors from using ++ on non-lists are common for beginners.

Forgetting that Haskell is lazy by default: Evaluating take 5 [1..1000000] doesn’t create a million-element list. But forcing strict evaluation with seq or foldl' can prevent space leaks. Understanding when laziness helps vs hurts is essential.