Lenses: compositional data access and manipulation. | SkillsCast
9th October 2013 in London There are 6 other SkillsCasts available from Haskell eXchange 2013 Please log in to watch this conference skillscast. Haskell lets you write beautiful, modular code. Rather than waffle generally, I’ll use this talk to look at a particular example, Edward Kmett’s lovely lens library. Lenses have been called “jQuery for data typesâ€: they give you a way to poke around in th
Lens Tutorial - Introduction (part 1) - Jakub Arnold Blog
Programovánà jako zábavná hra! DÄ›ti, ale i dospÄ›là se mohou nauÄit kódovat velice pÅ™Ãstupnou formou, která bude vÅ¡echny bavit! Foto: Pixabay Základy programovánà Programovánà se může zdát jako složitá vÄ›da, ale s dneÅ¡nÃmi dostupnými nástroji se tomuto Å™emeslu může nauÄit každý. SamozÅ™ejmÄ› záležÃ, jaké k tomu má kdo dispozice a kolik Äasu je ochoten uÄenà vÄ›novat. Už ale dávno neplatÃ, že je progra
Pinholes - Idiomatic Clojure Lenses
Lenses are a construct for getting, "setting" or "modifying" values within data structures, especially deeply nested data structures. The quotation marks have the usual meaning when they show up in funktionsprache:1 not mutating anything per se, but instead producing an object, or reference thereto, that is identical except for the requested change. In Scala, the need for lenses is pretty glaring,
CPS based functional references
I have recently come up with a new way of representing functional references. As you might recall, functional references (also called lenses) are like a pointer into a field of some data structure. The value of this field can be extracted and modified. For example: GHCi> get fstF (123,"hey") 123 GHCi> set fstF 456 (123,"hey") (456,"hey") GHCi> modify fstF (*2) (123,"hey") (246,"hey") where fstF is
Lensã“ã¨ã¯ã˜ã‚ - ã‚ã©ã‘ãªã„話
見ã‚ï¼ Haskell ㌠OOPL ã®ã‚ˆã†ã ï¼ ã•ã¦ã•ã¦ã€ã‚ˆã†ã‚„ãé‡ã„腰を上ã’ã¦ã€Lens を勉強ã—始ã‚ã¾ã—ãŸã‚ˆã€‚Haksell for allを見ã¦å‹‰å¼·ã™ã‚Œã°ã„ã„ã®ã‹ãªã¨æ€ã£ãŸã‚“ã§ã™ãŒã€è§£èª¬ã—ã¦ã„るパッケージ㌠data-lens ãªã®ã§å¤ã„ã§ã™ã。 今ã€ä½¿ã†ã¹ããªã®ã¯ã€lens ã¨ã„ã†ãƒ‘ッケージらã—ã„ã§ã™ã€‚解説ã¯ã€ã“ã® README ã‚’èªã‚€ã®ãŒä¸€ç•ªã ãã†ã§ã™ã€‚ã“ã® README 㨠Haskell for all ã‚’ã«ã‚‰ã‚ã£ã“ã—ãªãŒã‚‰ã€Lens ã® getter 㨠setter ã®æ©Ÿèƒ½ã‚’使ã£ã¦ã¿ã¾ã™ã€‚ 背景 Haskell ã®ä»£æ•°ãƒ‡ãƒ¼ã‚¿åž‹ã«ã¯ãƒ•ã‚£ãƒ¼ãƒ«ãƒ‰ãƒ©ãƒ™ãƒ«ãŒå®šç¾©ã§ãã¦ã€ã“ã‚ŒãŒã„ã‚ゆる getter 㨠setter ã®å½¹å‰²ã‚’æžœãŸã—ã¾ã™ã€‚Haskell for all ã‹ã‚‰ä¾‹ã‚’引用ã—ã¦ã¿ã¾ã—ょã†ã€‚ data Point = Point { x :: Double , y :: Do
A Little Lens Starter Tutorial - School of Haskell | School of Haskell
Interactive code snippets not yet available for SoH 2.0, see our Status of of School of Haskell 2.0 blog post What is lens?lens is a package which provides the type synonym Lens which is one of a few implementations of the concept of lenses, or functional references. lens also provides a number of generalizations of lenses including Prisms, Traversals, Isos, and Folds. Why do I care?Lenses and the
Lenses
Haskell's Lens type generalizes properties (i.e. accessors/mutators) found in other programming languages. For example, C# provides language support to treat properties as ordinary variables: class Point { public double x { get; set; } public double y { get; set; } } class Circle { public Point center { get; set; } public double radius { get; set; } } public void goRight(ref Circle c) { c.center.x
Lenses, Folds, and Traversals
Slides: http://comonad.com/haskell/Lenses-Folds-and-Traversals-NYC.pdf This was a talk I gave at the second New York Haskell User Group Meeting (http://www.meetup.com/NY-Haskell/) on the new lens library, which provides a highly composable toolbox for accessing and modifying multiple parts of data structures. Starting with building blocks such as fmap and (.), we build up combinators suitable fo
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