St Andrews Functional Programming Group

Who are we?

We are the functional programming group at the University of St Andrews. Functional programming involves writing programs using pure functions. Unlike conventional programming (including much object-oriented programming), side-effects are completely eradicated. This allows a very clean, very high-level, very concise programming model.

Functional programs are

Quick to write.

Easy to reason about.

Easy to modify and debug.

Easy to make parallel.

Previous work at St Andrews has focused on Parallel Implementation and Functional Persistence. Our parallel implementation work uses the Glasgow Parallel Haskell dialect of the non-strict functional language Haskell that has been developed in collaboration with researchers at Glasgow, Heriot-Watt and the Open University. Work on functional persistence has been done in collaboration with researchers from UCL and Universidade da Coruña, Spain.

News and Events

The latest St Andrews Functional Programming Group posts from the School of Computer Science blog.

Bidirectional-Curious? – Dr. Conor McBride

Event details

  • When: 22nd November 2017 13:00 - 14:30
  • Where: Cole 1.33b
  • Format: Talk

Type systems are often presented in a declarative style, but with an emphasis on ensuring that there is some sort of type synthesis algorithm. Since Pierce and Turner’s “Local Type Inference” system, however, there has been a small but growing alternative: bidirectional typing, where types are synthesized for variables and elimination forms, but must always be proposed in advance for introduction forms and checked. You can still get away without any type annotations, as long as you write only normal forms. But where’s the fun in that? If you want to write terms that compute, you need to write type annotations at exactly the point where an introduction form collides with its elimination form, showing exactly the type at which computation is happening.

For type systems with some sorts of value dependency, the bidirectional approach seriously cuts down on the amount of annotation required in terms, needed only to achieve type synthesis. We have a real opportunity to reduce clutter and also to give a clearer account of the connections between types and computation.

But it doesn’t stop there. A disciplined approach to the construction of bidirectional type systems makes it easier to get their metatheory right. I’ll show this by reconstructing Martin-Löf’s 1971 type theory (the inconsistent one) in a bidirectional style and show why it has type
preservation, even without normalization.

PhD viva success: Adam Barwell

Congratulations to Adam Barwell, who successfully defended his thesis yesterday. Adam’s thesis was supervised by Professor Kevin Hammond. He is pictured with second supervisor Dr Christopher Brown, Internal examiner Dr Susmit Sarkar and external examiner Professor Susan Eisenbach from Imperial College, London.