Haskell vs. PureScript vs. RemObjects Mercury vs. V Programming Language 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.

Mercury is an implementation of the BASIC programming language that is fully code-compatible with Microsoft Visual Basic.NET™, but takes it to the next level, and to new horizons. With Mercury, you will be able to build your existing VB.NET projects and leverage your Visual Basic™ language experience to write code for any modern target platform. You can mix Mercury code with any of the other five Elements languages in the same project if you like! The Mercury language will be deeply integrated into our development environments. Develop your projects in our smart yet lightweight IDEs, Water on Windows or Fire on Mac, with project templates, code completion, integrated debugging for all platforms, and many other advanced development features. Of course, Mercury will also integrate into Visual Studio™ 2017, 2019 and 2022. With Elements, all languages are created equal. Even within the same project, you can mix Mercury, C#, Swift, Java, Oxygene and Go.