BEGIN:VCALENDAR PRODID;X-RICAL-TZSOURCE=TZINFO:-//Calagator//EN CALSCALE:GREGORIAN X-WR-CALNAME:Calagator METHOD:PUBLISH VERSION:2.0 BEGIN:VTIMEZONE TZID;X-RICAL-TZSOURCE=TZINFO:America/Los_Angeles BEGIN:STANDARD DTSTART:20141102T020000 RDATE:20141102T020000 TZOFFSETFROM:-0700 TZOFFSETTO:-0800 TZNAME:PST END:STANDARD END:VTIMEZONE BEGIN:VEVENT CREATED;VALUE=DATE-TIME:20141208T074627Z DTEND;TZID=America/Los_Angeles;VALUE=DATE-TIME:20141207T210000 DTSTART;TZID=America/Los_Angeles;VALUE=DATE-TIME:20141207T190000 DTSTAMP;VALUE=DATE-TIME:20141208T074627Z LAST-MODIFIED;VALUE=DATE-TIME:20141208T074627Z UID:http://calagator.org/events/1250467464 DESCRIPTION:Jake Brownson will be presenting on his project River: \;\ n \;\n \;\n \;\nRiver is a purely functional reactive system bu ilt on top of C++11 \;\nwith some Ruby metaprogramming. It's reactiv e in the sense that as \;\ninputs to the program change invalidation s ripple through a big graph \;\nof functions until they hit the out puts which greedily reevaluate the \;\ngraph. One significant differ ence from other reactive systems is that \;\nthere is no notion of t ime\, or sequences of values at the language \;\nlevel. There is no notion of events\, or continuous streams of values. \;\nIt is just a big function that gets reevaluated as the input changes. \;\nWe can talk about these things using the system\, but they aren't first \; \nclass. \;\n \;\n \;\n \;\nOne key idea is to push all of the logical state out of the program \;\nitself and just make the ou tputs a big function of the inputs to the \;\nprogram. One big funct ion. \;\n \;\n \;\nInputs to the program can be things like th e total console input as a \;\nlist of characters\, a list of clicks the user has made\, etc. Outputs \;\nof the program are things like "\;There should be a window on screen"\; \;\n"\;The win dow should be called 'Frank'"\;\, "\;The window should have this \;\nbutton on it"\;\, etc. When the user clicks a button in the window the \;\ninputs change and a new output is calculated. Maybe the window is now \;\ncalled "\;Bob"\;. Maybe the window no longer is on screen\, but there's no \;\nstate in the program that i sn't a function of the inputs. \;\n \;\n \;\nInteractive Haske ll programs work by ultimately evaluating some lazy \;\nlist of thin gs that doesn't end until the program is terminated. \;\nThey're alw ays in a state of being partially evaluated until the \;\nprogram en ds. In each invalidation cycle the River program is fully \;\nevalua ted\, but the bits of it that are dependent on inputs that could \;\ nchange stay in memory so they can respond to changing inputs. An input \;\nlist may have been empty the first go around\, but now it has an item \;\nin it. \;\n \;\n \;\nI'm building River as the f irst phase of a larger project\, but would \;\nbe a whole different talk that hopefully I'll be able to do some day \;\nwhen I have some thing to demo. I'm always happy to rant about it if \;\nyou ask thou gh :). \;\n \;\n \;\nIf the group is interested I would be sho wing an AppKit GUI \;\nimplementation of the logic puzzle Akari runn ing in the system and \;\ndigging in to how things work a bit (don't worry\, I won't show the \;\nparticularly crazy c++ bits). I'll als o show an interactive \;\nvisualization of the in-memory graph that allows you to navigate it \;\nhierarchically which makes a great deb ugging tool. \;\n \;\n \;\n \;\nABOUT THE GROUP: Join progr ammers\, researchers and enthusiasts to discuss functional programming. pdxfunc is a study/user group exploring the world of functional programm ing based in Portland\, Oregon. The group welcomes programmers intereste d in all functional languages\, including Haskell\, OCaml\, Erlang\, Sca la and others\, as well as using functional techniques in non-functional languages. The group meets regularly and provides presentations\, demos and discussions applicable to all skill levels\, from newbies and exper ts. The meetings are usually on the second Monday of the month. \;\n\ n\nTags: functional programming\, pdxfunc\, haskell\, epdx:group=11\n\nI mported from: http://calagator.org/events/1250467464 URL:http://pdxfunc.org/ SUMMARY:pdxfunc: Portland Functional Programming Study Group LOCATION:Janrain Headquarters: 519 SW 3rd Ave. Suite 200\, Portland OR 97 204 US SEQUENCE:1 END:VEVENT END:VCALENDAR