He is an ACM Fellow, a Fellow of the Royal Society of Edinburgh, and editor-in-chief of Proceedings of the ACM for Programming Languages. Philip Wadler is Professor of Theoretical Computer Science at the University of Edinburgh and Senior Research Fellow at IOHK. The YouTube video of his Strange Loop talk Propositions as Types has over 75,000 views. He is a principal designer of the Haskell programming language, contributing to its two main innovations, type classes and monads. An example of practice into theory: Featherweight Java specifies the core of Java in less than one page of rules. An example of theory into practice: GJ, the basis for Java with generics, derives from quantifiers in second-order logic. Philip Wadler likes to introduce theory into practice, and practice into theory. In this talk I will describe three things I learned from writing PFLA, and I will touch on the role Agda plays in IOHK's new cryptocurrency. Finding an abstruse mathematical proof becomes as simple and as fun as hacking a program.Īccordingly, I have written a new textbook, Programming Language Foundations in Agda (PLFA), as a literate script for the proof assistant Agda. To prove properties of programming languages in Agda, all we need do is program a description of those languages Agda. Dependently-typed programming languages, such as Agda, exploit this pun. The proof of an implication is a function, proof by induction is just recursion. The doctrine of Propositions as Types asserts that propositions correspond to types, proofs to programs, and simplification of proofs to evaluation of programs.
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The most profound connection between logic and computation is a pun.
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Bachelor of Science in Computer Science.A strong type system is the opposite of a weak type system. The opposite of a dynamic type system is a static type system, not a strong type system. When you get an error message, the compiler is only telling you at compile time what a language with dynamic types would tell you at runtime. Haskell also features type inference which alleviates verbosity when compared to languages like C++ and Java. People who program tend to, even when using dynamic languages, follow typing conventions that can be encoded using Haskell's type system. The type system shouldn't be a huge obstacle. If you want a broad and rounded education in computer science and programming language design in particular, Haskell would be an excellent choice as one of the languages that you should learn. Haskell is a very good example of a language with a strong, static type system. Unless you can isolate effects in another way or you remove effects entirely, a strong static type system is a requirement for pure functional programming.
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Haskell's type system is key to its ability to isolate effects from pure code. Finally, I realized that Haskell's type system was actually very expressive and started designing my programs around types. I even had a lazy phase where I did refactoring by changing a function type and letting the compiler tell me what else needed to be changed. I then discovered that programs that passed the type check were usually correct, or at least close to correct. accidentally using map instead of concatMap). I soon discovered that many of the type errors the compiler complained about things that wouldn't have worked anyway even if the compiler had let me do them (e.g. When I first started using Haskell, I considered the type system to be annoying, and only tolerated it because of type inference. Both definitely have their strong points, so you may want to consider Clojure if you really don't like Haskell's rigidity (but see below). Clojure is dynamically-typed, and almost as pure as Haskell, so there's a good argument that the Haskell's type system was more of a design choice than an absolute requirement.