Crystal vs. Haskell vs. Java vs. Ruby Comparison Chart

Every expression in Haskell has a type that is determined at compile time. All the types composed together by function application have to match up. If they don't, the program will be rejected by the compiler. Types become not only a form of guarantee, but a language for expressing the construction of programs. Every function in Haskell is a function in the mathematical sense (i.e., "pure"). Even side-effecting IO operations are but a description of what to do, produced by pure code. There are no statements or instructions, only expressions that cannot mutate variables (local or global) nor access state like time or random numbers. You don't have to explicitly write out every type in a Haskell program. Types will be inferred by unifying every type bidirectionally. However, you can write out types if you choose, or ask the compiler to write them for you for handy documentation.

Wondering why Ruby is so popular? Its fans call it a beautiful, artful language. And yet, they say it’s handy and practical. Since its public release in 1995, Ruby has drawn devoted coders worldwide. In 2006, Ruby achieved mass acceptance. With active user groups formed in the world’s major cities and Ruby-related conferences filled to capacity. Ruby-Talk, the primary mailing list for discussion of the Ruby language, climbed to an average of 200 messages per day in 2006. It has dropped in recent years as the size of the community pushed discussion from one central list into many smaller groups. Ruby is ranked among the top 10 on most of the indices that measure the growth and popularity of programming languages worldwide (such as the TIOBE index). Much of the growth is attributed to the popularity of software written in Ruby, particularly the Ruby on Rails web framework.