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Sequent Calculus as a Compiler Intermediate LanguageSequent Calculus as a Compiler Intermediate Language
By Andris Birkmanis at 2018-04-02 17:06 | Functional | General | Lambda Calculus | Semantics | Type Theory | 2 comments | other blogs | 6187 reads
How to Write Seemingly Unhygienic and Referentially Opaque Macros with Syntax-rules
How to Write Seemingly Unhygienic and Referentially
Opaque Macros with Syntax-rules
By Oleg Kiselyov This paper details how folklore notions of hygiene and referential transparency of R5RS macros are defeated by a systematic attack. We demonstrate syntax-rules that seem to capture user identifiers and allow their own identifiers to be captured by the closest lexical bindings. In other words, we have written R5RS macros that accomplish what commonly believed to be impossible. By Andris Birkmanis at 2018-03-22 02:22 | Fun | Meta-Programming | 35 comments | other blogs | 8591 reads
Why Is SQLite Coded In CWe are nearing the day someone quips that C is an improvement on most of its successors (smirk). So reading this page from the SQLite website is instructive, as is reading the page on the tooling and coding practices that make this approach work. I think none of this is news, and these approaches have been on the books for quite a bit. But still, as I said: an improvement on most of its successors. Hat tip: HN discussion. Resource PolymorphismResource Polymorphism, by Guillaume Munch-Maccagnoni:
An ambitious goal, and it would be an incredibly useful addition to OCaml. Might even displace Rust in some places, since you can theoretically avoid triggering the GC, but you have the excellent GC available when needed. This is definitely a pain point for Rust. By naasking at 2018-03-08 14:40 | Functional | login or register to post comments | other blogs | 9508 reads
The Left Hand of EqualsThe Left Hand of Equals, by James Noble, Andrew P. Black, Kim B. Bruce, Michael Homer, Mark S. Miller:
This covers a lot of ground, not only historical, but conceptual, like the meaning of equality and objects. For instance, they consider Ralph Johnson on what object oriented programming means:
And constrast with William Cook's autognosis/procedural-abstraction view, which we've discussed here before. The paper's goal then becomes clear: "What can we do to provide an equality operator for a pure, autognostic object-oriented language?" They answer this question in the context of the Grace programming language. As you might expect from some of the authors, security and trust are important considerations. Site migrationUpdate: The migration of LtU to new servers is complete. If you notice any issues with the site, please post in this thread (if you can), or email me at antonvs8 at (gmail domain). Original announcement appears below:
By Anton van Straaten at 2018-02-04 20:03 | Site Discussion | 11 comments | other blogs | 14734 reads
Compiling a Subset of APL Into a Typed Intermediate Language
Compiling a Subset of APL Into
a Typed Intermediate Language
by Martin Elsman, Martin Dybdal Traditionally, APL is an interpreted language ... In this paper, we present a compiler that compiles a subset of APL into a typed intermediate representation, which should serve as a practical and well-defined intermediate format for targeting parallel-architectures through a large number of existing tools and frameworks. The intermediate language is conceptually close to the language Repa. It supports shape-polymorphic functions and types that classify shapes. The compiler takes a simplified approach to certain aspects of APL. Following other APL compilation approaches, the compiler is based on lexical (i.e., static) identifier scoping and has no support for dynamic compilation (APL execute).Terseness of APL is legendary, for good or bad. I keep finding more and more papers by Haskell community (and especially GHC contributors) working on efficient (parallel) arrays in Haskell. People of Programming Languages InterviewsThere is a growing set of fascinating interviews with PL folks at People of Programming Languages. By bashyal at 2017-12-31 15:17 | History | login or register to post comments | other blogs | 20625 reads
Exploiting Vector Instructions with Generalized Stream Fusion
Exploiting Vector Instructions with Generalized Stream Fusion
By Geoffrey Mainland, Roman Leshchinskiy, and Simon Peyton Jones. A.k.a. "Haskell beats C".
Our ideas are implemented in modified versions of the GHC compiler and vector library. Benchmarks show that high-level Haskell code written using our compiler and libraries can produce code that is faster than both compiler- and hand-vectorized C. This paper continues the promising line of research started in 1990 by Wadler (at least, that was how I learned of deforestation). Of course, there was a lot of development since then, but this specific paper introduces an interesting idea of multiple representations - potentially changing the game. By Andris Birkmanis at 2017-12-22 03:33 | Implementation | login or register to post comments | other blogs | 31247 reads
How efficient is partial sharing?Partial sharing graphs offer a reduction model for the lambda calculus that is optimal in a sense put forward by Jean Jacques Levy. This model has seen interest wax and wane: initially it was thought to offer the most efficient possible technology for implementing the lambda calculus, but then an important result showed that bookkeeping overheads of any such model could be very high (Asperti & Mairson 1998). This result had a chilling effect on the initial wave of excitement over the technology. Now Stefano Guerrini, one of the early investigators of partial sharing graphs, has an article with Marco Solieri (Guerrini & Solieri 2017) arguing that the gains from optimality can be very high and that partial sharing graphs can be relatively close to the best possible efficiency, within a quadratic factor on a conservative analysis (this is relatively close in terms of elementary recursion). Will the argument and result lead to renewed interest in partial sharing graphs from implementors of functional programming? We'll see... (Asperti & Mairson 1998) Parallel beta reduction is not elementary recursive. (Guerrini & Solieri 2017) Is the Optimal Implementation inefficient? Elementarily not. |
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