Crystal vs. D vs. SQL vs. Unlambda Comparison Chart

D is a general-purpose programming language with static typing, systems-level access, and C-like syntax. With the D Programming Language, write fast, read fast, and run fast. D is made possible through the hard work and dedication of many volunteers, with the coordination and outreach of the D Language Foundation, a 501(c)(3) non-profit organization. You can help further the development of the D language and help grow our community by supporting the Foundation. Discuss D on the forums, join the IRC channel, read our official Blog, or follow us on Twitter. Browse the wiki, where among other things you can find the high-level vision of the D Language Foundation. Refer to the language specification and the documentation of Phobos, D's standard library. The DMD manual tells you how to use the compiler. Read various articles to deepen your understanding.

Unlambda is a programming language. Nothing remarkable there. The originality of Unlambda is that it stands as the unexpected intersection of two marginal families of languages. Functional programming languages, of which the canonical representative is Scheme (a Lisp dialect). This means that the basic object manipulated by the language (and indeed the only one as far as Unlambda is concerned) is the function. Rather, Unlambda uses a functional approach to programming: the only form of objects it manipulates are functions. Each function takes a function as an argument and returns a function. Apart from a binary “apply” operation, Unlambda provides several built-in functions (the most important ones being the K and S combinators). User-defined functions can be created, but not saved or named, because Unlambda does not have any variables.