One of the pleasant new features in GHC 6.10 is the long-awaited addition of view patterns. This feature is usually advertised as making it possible to pattern match against the values of an abstract type. An essential aspect of modular software design is that we don't want to expose the implementation of complex code. Someone will surely come along and start making decisions based on bits of our code that they can see, thus limiting our future room to manoeuvre. This is all amply explained on the view pattern wiki page and in the GHC User's Guide. how do they diff from f# active pats
This article is part three in a series on introductory Haskell programming. In the first article, we wrote a small program to recursively scan file-system directories and print their contents as ASCII-art trees. In the second article, we refactored the program to make its logic more reusable by separating the directory-scanning logic from the tree-printing logic. In this article, we will address a shortcoming of the refactored version: It must scan directory hierarchies completely before printing their trees, i.e., it must scan and then print, when doing both simultaneously is both more efficient and more user friendly. Recall from the previous article that our directory-printing program is factored into three pieces of logic:
Advantages of Soft Typing This is a continuation of this discussion. The main points for soft typing are as follows. * Compile time type checks. Soft typing can catch the same amount of provable errors at compile time as static typing. * Automatic downcasts. Downcasts are done automatically assuming the program passes type checking. The main argument for explicit casts is that it provides the programmer with more information, but this is a misnomer. One does not have to write down information for it to be shown to him, so long as said information is inferrable. Note: whether or not you believe OCaml doesn't have casting is irrelevant, simply assume that, when I refer to casting, I also mean situations in which it's emulated. * Unimposing. Unless a piece of code is provably incorrect at compile time, the compiler can insert runtime checks.
Welcome to the largest bibliographic database dedicated to Economics and available freely on the Internet. Over 750'000 items of research can be browsed or searched, and over 600'000 can be downloaded in full text! This site is part of a large volunteer effort to enhance the free dissemination of research in Economics, RePEc. To see the popularity of these services, browse the statistics at LogEc
This site is an experimental HTML rendering of fragments of the IsarMathLib project. IsarMathLib is a library of mathematical proofs formally verified by the Isabelle theorem proving environment. The formalization is based on the Zermelo-Fraenkel set theory. The Introduction provides more information about IsarMathLib. The software for exporting Isabelle's Isar language to HTML markup is at an early beta stage, so some proofs may be rendered incorrectly. In case of doubts, compare with the Isabelle generated IsarMathLib proof document.
Vampire is winning at least one division of the world cup in theorem proving CASC since 1999. All together Vampire won 17 titles: more than any other prover. We traditionally take part in the following two divisions of the competition: * The FOF division: unrestricted first-order problems. This division was ranked second in importance after the MIX division before 2007 and is now recognised as the main competition division. * The CNF division: first-order problems in conjunctive normal form. This division was called MIX before 2007 and recognised as the main competition division. We also participate in other, more special competition divisions but Vampire is not specialised for them so our achievements are mostly modest.
In the fully expansive (or LCF-style) approach to theorem proving, theorems are represented by an abstract type whose primitive operations are the axioms and inference rules of a logic. Theorem proving tools are implemented by composing together the inference rules using ML programs. This idea can be generalised to computing valid judgements that represent other kinds of information. In particular, consider judgements (a,r,t,b), where a is a set of boolean terms (assumptions) that are assumed true, r represents a variable order, t is a boolean term all of whose free variables are boolean and b is a BDD. Such a judgement is valid if under the assumptions a, the BDD representing t with respect to r is b, and we will write a r t --> b when this is the case. The derivation of "theorems" like a r t --> b can be viewed as "proof" in the style of LCF by defining an abstract type term_bdd that models judgements a r t --> b analogously to the way the type thm models theorems |- t.
CryoPID allows you to capture the state of a running process in Linux and save it to a file. This file can then be used to resume the process later on, either after a reboot or even on another machine. Status CryoPID was spawned out of a discussion on the Software suspend mailing list about the complexities of suspending and resuming individual processes. CryoPID consists of a program called freeze that captures the state of a running process and writes it into a file. The file is self-executing and self-extracting, so to resume a process, you simply run that file. See the table below for more details on what is supported. Features Current features are: * Can run as an ordinary user! (no root privileges needed) * Works on both 2.4 and 2.6. * Works on x86 and AMD64. * Can start & stop a process multiple times * Can migrate processes between machines and between kernel versions (tested between 2.4 to 2.6 and 2.6 to 2.4).
This page represents the current state of an ongoing effort to collect information about existing automated reasoning systems. One objective is to provide concise useful information for people who have need for such a system and don't want to `roll their own'. Another objective is to provide a single place where information about existing systems can be accessed, thus providing an overview of the state of the art.
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