Functional Programming in an Imperitive World
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From FPX 2015, video at: https://skillsmatter.com/skillscasts/6417-functional-programming-in-an-imperative-world#video Once upon a time there was a small company with a large codebase. That codebase had been written in the well understood languages of "VeeBeeDotNet" and "CeeSharp". After a while, more people starting working for the small company, and while they all knew some CeeSharp and VeeBeeDotNet, some of them also spoke strange foreign languages like "Erlang" and "EffSharp". They liked these languages, and were unwilling to give up what they saw as their powerful magical properties of pureness. So they hatched a plan.. This talk is a completely anecdotal review of how a group of developers (not managers) introduced functional techniques and languages into a company with an existing imperative code base - and existing imperative coders! Learn how we convinced management it wasn't insane. How we picked low risk, high impact tasks to illustrate language advantages. And how we spread the joy to others who hadn't used functional programming languages before.
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Functional Programming in an Imperitive World
- 2. Once upon a time there was a small company with a large codebase. That codebase had been written in the well understood languages of "VeeBeeDotNet" and "CeeSharp". After a while, more people started working for the small company, and while they all knew some “CeeSharp” and “VeeBeeDotNet”, some of them also spoke strange foreign languages like "Erlang" and "EffSharp". They liked these languages, and were unwilling to give up what they saw as their powerful magical properties of purity. So they hatched a plan…
- 3. etting the scene "Alphabet-Golden-Bible-letter-S" by SVG Perhelion (Original unknown) - Own work; Shaw, Henry: “Alphabets & Numbers of the Middle Ages” (1845) FROM THE GOLDEN BIBLE, printed at Augsburg[1] http://www.archive.org/details/handbookofmediae00shawrich. Licensed under CC BY 3.0 via Wikimedia Commons- http://commons.wikimedia.org/wiki/File:Alphabet-Golden-Bible-letter-S.svg#/media/File:Alphabet-Golden-Bible-letter-S.svg
- 5. https://www.flickr.com/photos/donkeyhotey/16339664626 CC licensed - http://creativecommons.org/licenses/by-nc-sa/2.0/
- 6. ear is the mind killer "Alphabet-Golden-Bible-letter-F" by SVG Perhelion (Original unknown) - Own work; Shaw, Henry: “Alphabets & Numbers of the Middle Ages” (1845) FROM THE GOLDEN BIBLE, Printed at Augsburg[1] http://www.archive.org/details/handbookofmediae00shawrich. Licensed under CC BY 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Alphabet-Golden-Bible-letter-F.svg#/media/File:Alphabet-Golden-Bible-letter-F.svg
- 7. •Change is hard – and risky •Need to convince: •Management •Your peers Fear is the mind killer
- 9. [Dan Luu’s] post “The Empirical Evidence That Types Affect Productivity and Correctness” summarizes a large set of papers and goes through each one in order to describe what it is trying to measure and how well it does it. In almost every paper, he has valid critique of the experiment, methodology and approach. https://medium.com/@jlouis666/proglang-design-with-evidence-1444213f3902
- 10. ilute the risk "Alphabet-Golden-Bible-letter-D" by SVG Perhelion (Original unknown) - Own work; Shaw, Henry: “Alphabets & Numbers of the Middle Ages” (1845) FROM THE GOLDEN BIBLE, Printed at Augsburg[1] http://www.archive.org/details/handbookofmediae00shawrich. Licensed under CC BY 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Alphabet-Golden-Bible-letter-F.svg#/media/File:Alphabet-Golden-Bible-letter-D.svg
- 11. •Fix the badly broken Dilute the risk
- 12. <?xml version="1.0" encoding="utf-8"?> <Project ToolsVersion="12.0" DefaultTar <Import Project="$(MSBuildExtensions <PropertyGroup> <Configuration Condition=" '$(Conf <Platform Condition=" '$(Platform) <SchemaVersion>2.0</SchemaVersi <ProjectGuid>023b9a33-3d12-4878 <OutputType>Library</OutputType>
- 14. •Fix the badly broken •Pick an interoperable language Dilute the risk
- 20. o the impossible "Alphabet-Golden-Bible-letter-D" by SVG Perhelion (Original unknown) - Own work; Shaw, Henry: “Alphabets & Numbers of the Middle Ages” (1845) FROM THE GOLDEN BIBLE, Printed at Augsburg[1] http://www.archive.org/details/handbookofmediae00shawrich. Licensed under CC BY 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Alphabet-Golden-Bible-letter-F.svg#/media/File:Alphabet-Golden-Bible-letter-D.svg
- 21. •What’s so risky it’s never been done? •Can a functional language help? Do the impossible
- 22. “Ripper 5” Storn Cook, http://www.enworld.org/forum/showthread.php?161795-Storn-s-art-for-swipin-!/page12 CC licensed - http://creativecommons.org/licenses/by-nc-sa/2.5/ The Heroes
- 23. Type Providers
- 24. Pattern Matching
- 25. Concurrency
- 26. Currying
- 27. Metaprogramming
- 28. teal from the best "Alphabet-Golden-Bible-letter-S" by SVG Perhelion (Original unknown) - Own work; Shaw, Henry: “Alphabets & Numbers of the Middle Ages” (1845) FROM THE GOLDEN BIBLE, printed at Augsburg[1] http://www.archive.org/details/handbookofmediae00shawrich. Licensed under CC BY 3.0 via Wikimedia Commons- http://commons.wikimedia.org/wiki/File:Alphabet-Golden-Bible-letter-S.svg#/media/File:Alphabet-Golden-Bible-letter-S.svg
- 29. •If you can’t go to the functional language… •…bring the functional concepts to yours •And then tell people where they came from! Steal from the best
- 30. Actors
- 33. inally "Alphabet-Golden-Bible-letter-F" by SVG Perhelion (Original unknown) - Own work; Shaw, Henry: “Alphabets & Numbers of the Middle Ages” (1845) FROM THE GOLDEN BIBLE, Printed at Augsburg[1] http://www.archive.org/details/handbookofmediae00shawrich. Licensed under CC BY 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Alphabet-Golden-Bible-letter-F.svg#/media/File:Alphabet-Golden-Bible-letter-F.svg
- 34. Teach https://www.flickr.com/photos/vancouver-archives/6345489958 CC licensed - http://creativecommons.org/licenses/by-nc-sa/2.0/
- 35. “Old Paper” background courtesy of http://www.pieceofeight.com/ https://www.flickr.com/photos/67779350@N00/167159577/ Attribution 2.0 Generic (CC BY 2.0) Questions? @mavnn http://blog.mavnn.co.uk @15below_tech http://www.15below.com
Notes de l'éditeur
- Not finished 5-6 F#ers Most new code still C#
- Company started 2000 RyanAir VB6 csv processing Microsoft shop
- Changing personal comms Changing expectations Changing code base
- Buy in that change needed But: don’t kill the golden goose 2+ million lines of code in 2012 Rapidly expanding development team
- Lot’s going on: C#, Git, TeamCity, Automated Deploys What about functional? 15min
- Need to convince up (risk averse monetarily) Need to convince across (change aversion, new skills required)
- Can’t just point at a study and came an RoI Don’t sell FP: sell a solution to a problem That might mean FP is a by product of your solution Jesper L. Andersen
- Need to reduce fear How? 15-20 min
- Fix the badly broken
- Things that work really well together Keep the old, use with the new Unit tests!
- Sproc.Lock, Parser code
- Play framework
- Not so sure Java -> Clojure?
- Or ClojureScript, FunScript, PureScript, Ocamljs, ghcjs, scala.js…
- 25-30min
- Hard to be compatible? Can’t find anything already broken? Look for the “impossible” that hasn’t been done yet.
- Find something the current tech is bad at Come in like a superhero Convince management and rest of team
- Compile time checks of interesting things (write your own printf) Explore complex datasets Looks magic! Even (especially?) to non experts
- *NOT DOMAIN READABILITY!* Massive savings of time/code in certain types of scenarios Parsing Rules logic (Active patterns)
- Side effect of purity …but lots of good options in functional langs
- Huge readability gain for non-coders {} people will tell you it looks strange But get the domain experts to read the code (Jane Street, Simon Cousins)
- Not actually related to FP But lots of FP langs have good metaprogramming
- Bring concepts from functional programming into the existing codebase Publicise where they came from! 35min
- Bring concepts from functional programming into the existing codebase Publicise where they came from!
- Message passing with the actor model Akka(.net) Functional? Maybe. Build awareness/acceptance
- Property based testing QuickCheck, FsCheck Just keep on putting shapes that match in
- Just write functional code! And teach others too
- 40min
- DevEds A selection from the above: unit tests, build scripting, FsCheck, parsing DevEds (Linus Pauling)