Haskell Programming Interview Questions And Answers

Haskell is an advanced purely functional programming language. The product of more than twenty years of cutting edge research, it allows rapid development of robust, concise, correct software. With strong support for integration with other languages, built-in concurrency and parallelism, debuggers, profilers, rich libraries and an active community, Haskell makes it easier to produce flexible, maintainable high-quality software.

Haskell distinguishes function calls from infix operators syntactically, but not semantically. Function names which are composed of punctuation characters can be used as operators, as can other function names if surrounded with backticks; and operators can be used in prefix notation if surrounded with parentheses.

Haskell is a general purpose programming language. It was designed without any application niche in mind. Although it takes a strong stand on how programs should be written, it does not favor one problem domain over others.

Languages that use simple static type systems have been the mainstay of the programming world for decades. Haskell is statically typed, but its notion of what types are for, and what we can do with them, is much more flexible and powerful than traditional languages. Types make a major contribution to the brevity, clarity, and efficiency of Haskell programs.

Although powerful, Haskell's type system is often also unobtrusive. If we omit explicit type information, a Haskell compiler will automatically infer the type of an expression or function. Compared to traditional static languages, to which we must spoon-feed large amounts of type information, the combination of power and inference in Haskell's type system significantly reduces the clutter and redundancy of our code.

Over the past decade, dynamically typed, interpreted languages have become increasingly popular. They offer substantial benefits in developer productivity. Although this often comes at the cost of a huge performance hit, for many programming tasks productivity trumps performance, or performance isn't a significant factor in any case.

Brevity is one area in which Haskell and dynamically typed languages perform similarly: in each case, we write much less code to solve a problem than in a traditional language. Programs are often around the same size in dynamically typed languages and Haskell.

For practical work, almost as important as a language itself is the ecosystem of libraries and tools around it. Haskell has a strong showing in this area.
The most widely used compiler, GHC, has been actively developed for over 15 years, and provides a mature and stable set of features.

► Compiles to efficient native code on all major modern operating systems and CPU architectures
► Easy deployment of compiled binaries, unencumbered by licensing restrictions
► Code coverage analysis
► Detailed profiling of performance and memory usage
► Thorough documentation
► Massively scalable support for concurrent and multicore programming
► Interactive interpreter and debugger