Haskell Practice (Basics)
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
Intuition
Haskell’s type system is your ally, not your enemy: Strong static types catch errors before code runs. Pattern matching, algebraic data types, and type classes provide expressive power without sacrificing safety.
Why it matters: Haskell’s approach to types and pure functions leads to code that is easier to test, refactor, and reason about.
The key insight: List comprehensions and higher-order functions (map, filter, fold) replace loops, thinking in transformations rather than iterations is the key to functional programming.
Common Mistakes
Forgetting that Haskell uses 0-based indexing: Lists and arrays in Haskell are indexed from 0. xs !! 0 gives the first element. Using 1-based indexing from other languages causes off-by-one errors.
Confusing = (definition) with == (equality test): = defines a name; == tests equality. Using = in a guard or comparison context is a syntax error. This is a common mistake for programmers from C-family languages.
Ignoring the type checker: Haskell has one of the most powerful type systems in mainstream use. When the type checker complains, it is almost always telling you something is wrong. Read the error message carefully, it in most cases points directly to the bug.
See Also
Detailed Content
Core Concepts
Worked Examples
Common Mistakes
- Rushing through foundational material
- Not practising problems after reading
- Failing to connect concepts across topics