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FunctionalDependentlyTyped Metaprogramming (in Agda)Conor McBride gave an 8lecture summer course on Dependently typed metaprogramming (in Agda) at the Cambridge University Computer Laboratory:
The lecture notes, code, and video captures are available online. As with his previous course, the notes contain many(!) mind expanding exploratory exercises, some of which quite challenging. By Ohad Kammar at 20130830 07:34  Category Theory  Functional  Lambda Calculus  MetaProgramming  Paradigms  Semantics  Teaching & Learning  Theory  Type Theory  5 comments  other blogs  13342 reads
Extensible Effects  An Alternative to Monad TransformersExtensible Effects  An Alternative to Monad Transformers, by Oleg Kiselyov, Amr Sabry and Cameron Swords:
A followup to Oleg's delimited continuation adaptation of Cartwright and Felleisen's work on Extensible Denotational Language Specifications, which is a promising alternative means of composing effects to the standard monad transformers. This work embeds a userextensible effect EDSL in Haskell by encoding all effects into a single effect monad using a novel open union type and the continuation monad. The encoding is very similar to recent work on Algebraic Effects and Handlers, and closely resembles a typed clientserver interaction ala coroutines. This seems like a nice convergence of the topics covered in the algebraic effects thread and other recent work on effects, and it's more efficient than monad transformers to boot. By naasking at 20130729 14:53  Functional  Logic/Declarative  Theory  Type Theory  22 comments  other blogs  28953 reads
How OCaml type checker works  or what polymorphism and garbage collection have in commonHow OCaml type checker works  or what polymorphism and garbage collection have in common
As usual with Oleg, there's a lot going on here. Personally, I see parallels with "lambda with letrec" and "callbypushvalue," although making the connection with the latter takes some squinting through some of Levy's work other than his CBPV thesis. Study this to understand OCaml type inference and/or MLF, or for insights into region typing, or, as the title suggests, for suggestive analogies between polymorphism and garbage collection. By Paul Snively at 20130310 16:25  Functional  Implementation  Type Theory  1 comment  other blogs  14895 reads
Visi.ioVisi.io comes from David Pollak and aims at revolutionizing building tablet apps, but the main attraction now seems to be in exploring the way data flow and cloud computing can be integrated. The screencast is somewhat underwhelming but at least convinces me that there is a working prototype (I haven't looked further than the website as yet). The vision document has some nice ideas. Visi.io came up recently in the discussion of the future of spreadsheets. By Ehud Lamm at 20121027 09:36  Functional  Logic/Declarative  Parallel/Distributed  2 comments  other blogs  11711 reads
Milner Symposium 2012The Milner Symposium 2012 was held in Edinburgh this April in memory of the late Robin Milner.
The programme consisted of academic talks by colleagues and past students. The talks and slides are available online. I particularly liked the interleaving of the personal and human narrative underlying the scientific journey. A particularly good example is Joachim Parrow's talk on the origins of the pi calculus. Of particular interest to LtU members is the panel on the future of functional programming languages, consisting of Phil Wadler, Xavier Leroy, David MacQueen, Martin Odersky, Simon PeytonJones, and Don Syme. By Ohad Kammar at 20121016 17:31  Functional  General  History  Parallel/Distributed  Semantics  Theory  3 comments  other blogs  12961 reads
CUFP 2012 TutorialsIf you are in Denmark in September you should attend. If not, raise a glass to salute what is now abundantly clear: FPLs are conquering the ("real") world. Koka a function oriented language with effect inference
Koka extends the idea of using row polymorphism to encode an effect system and the relations between them. Daan Leijen is the primary researcher behind it and his research was featured previously on LtU, mainly on row polymorphism in the Morrow Language. So far there's no paper available on the language design, just the slides from a Lang.Next talk (which doesn't seem to have video available at Channel 9), but it's in the program for HOPE 2012. By Daniel Yokomizo at 20120816 05:40  Functional  Software Engineering  Type Theory  3 comments  other blogs  17746 reads
Mechanized Î»<sub>JS</sub>Mechanized Î»_{JS}
More work on mechanizing the actual, implemented semantics of a real language, rather than a toy. By Paul Snively at 20120627 15:28  Functional  Javascript  Lambda Calculus  Semantics  6 comments  other blogs  12548 reads
How to Make Ad Hoc Proof Automation Less Ad HocHow to Make Ad Hoc Proof Automation Less Ad Hoc
If you've ever toyed with Coq but run into the difficulties that many encounter in trying to construct robust, comprehensible proof scripts using tactics, which manipulate the proof state and can leave you with the "ground" of the proof rather than the "figure," if you will, in addition to being fragile in the face of change, you may wish to give this a read. It frankly never would have occurred to me to try to turn Ltac scripts into lemmas at all. This is much more appealing than most other approaches to the subject I've seen. By Paul Snively at 20120622 15:41  Functional  Implementation  Logic/Declarative  Type Theory  9 comments  other blogs  8185 reads
Validating LR(1) parsers
I've always been somewhat frustrated, while studying verified compiler technology, that the scope of the effort has generally been limited to ensuring that the AST and the generated code mean the same thing, as important as that obviously is. Not enough attention has been paid, IMHO, to other compiler phases. Parsing: The Solved Problem That Isn't does a good job illuminating some of the conceptual issues that arise in attempting to take parsers seriously as functions that we would like to compose etc. while maintaining some set of properties that hold of the individuals. Perhaps this work can shed some light on possible solutions to some of those issues, in addition to being worthwhile in its own right. Note the pleasing presence of an actual implementation that's been used on the parser of a realworld language, C99. By Paul Snively at 20120618 15:15  DSL  Functional  Implementation  Theory  4 comments  other blogs  8885 reads

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