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Future-proofing Scala: the TASTY intermediate representation
Guillaume Martres, student at EPFL
Wednesday, June 12, 2019 · 10:18 a.m. · 44m 52s
Compiling Scala to JVM bytecode is not trivial and has surprising consequences for binary compatibility (see the talk "Designing libraries for source and binary compatibility"). Compiling all your Scala dependencies from sources sidesteps this but has other disadvantages: it's slow, and because type inference in Scala changes, source compatibility is not guaranteed. TASTY is a format developed as part of Dotty as a middle-ground by storing the compiler ASTs after type inference. It turns out that this has many uses, come to this talk to find out how it works and what we can do with it!
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okay i run my name is john i'm the pitches shouldn't that if if a working on
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the the to compare and they like to talk to you about this cool new format we quite
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tasty and what it means for the future of scare ah ah so to begin with ah i'd
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like to talk about upgrading is cast so imagine your writing this act really could up he's kinda
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and choosing a scared to drive but it's got to fourteen was just freeze a few days ago it has all this
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cool new things like when you corrections and you really want to use it so you say okay i'm just going to change
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this correction in my program from two twelve to fourteen and
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if you just use this class so not every then that's fine
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but as soon as you have dependencies which have been already compared
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against two twelve you can't do that uh because it is the
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finances won't be able to use when you still not every in
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the new version of the car and uh there's the finances themselves
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might not be able to a bright to scatter for teen until
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their own dependencies have been upgraded to scatter for teen and whoa
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ah screen is rated cough okay it's
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how can i i if it's you know it's ah so what needs to happen is first order of uh
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dependencies are the root of the tree which usually are things like scared tends to scare check cats need to
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upgrade to two fourteen then uh the libraries that uses
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this rubber is that we depend on you to upgrade it
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and then finally you can start using skirt to for putting 'em so why does
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this happen what what's going on here exactly ah so to expand that first thing to
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explain what binary compatibility is so uh in a very big no chair i imagine
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i have a project a which is compared against some specific version x. of project be
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and then i want to run this project with a different version of project
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week and if it doesn't fork where it doesn't fork resume insect crush at
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one time when we say that x. and one why are binary incompatible and
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if you want more details you should go to each c. d. score some
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torque uh which is a new to base about yeah about how to design
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libraries for source and binary compatibility okay uh uh so we understand this but
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why what this kind of need to break binary compatibility every two years lack
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is is just a fact of life um so so you really it's because like
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you want to change things like because you realise there's some other way to do
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things or better way to do things all the way that didn't exist before but
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sunshine is a really hard or almost impossible to make without breaking binary compatibility so
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in a way to to be given to to for transition the biggest of exchanges
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or or multiple ones but the biggest one what anyone could infiltrate uh based on
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the news report for the for the for this in java eight which means um
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number of things that the implementation of special much simpler but it also means that
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the uh including and to be completely different situ used this cat we given um
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i think i'd classified uh you couldn't use it be for the
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us cut to twelve compact classified because they just didn't uh speak
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the same uh language and from two for two two fourteen um
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of of the main reason for working men are competitive was not
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at the level of a language itself but with would've been over standard library we
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have us to not collection was redesigned and particular of a euro q. of classes which
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is something that is very but basically impossible to change uh we for breaking binary compatibility
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due to how virgin works okay but ah yeah there's always a good reason basically but
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uh can we can we maintain compatibility worst here everything's gonna and yeah i i don't
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really know but yeah maybe we should try because unlike barking competitor over time is is such
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a a click makes it really hard for people to upgrade to train versions so so maybe
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we can try to do things that you to be different and see how it goes um
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have things like when interesting example of how things can be done exists already is gonna and that's
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it's gonna g. s. so so it's you can say well it's not really like it's on language but
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i mean kind of is really it's uh it pretends to be a camper pretty inverted tree look cool compared to there's a
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lot of things it's crazy ah and was three crazies that it
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has maintained binary compatibility for more than four yeah zack longer when
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the times the lifetime of us correction uh and what what this
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means so this this multiple things 'cause gonna g. s. provides a
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j. d. n. a. p. i. for a like using those catches
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gunfire are for the noisy to plug ins effect that we'd also
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indian is going to output javascript but when you make a
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schedule guess a project and you uh like publish your jar
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two maven the job doesn't count ten j. j.'s files and set
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contents is g. s. i. r. files which is you slack on
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custom intermediates presentation that sky g. s. uses and when you compare
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your own project uh this guy just encourage going to take all this
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is j. c. i. offers from all your dependencies as input to
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eventually produce javascript and that number is a bunch of interesting things that
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could program optimisation since vector the schedules can see everything that uses
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it's able to do really requires you to musicians will also means but
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uh i don't know if they decide to change how to generate javascript we can still
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use oh it is g. s. i. r. fires and because there's like a version number in
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this race hellfire we can just uh decide oh this is an old file but we
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know how to interpret it to make it do things the way we want to do now
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and that's like the secret to maintain compatibility for a very long time
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um okay so what we get from that but can we make our own format which would be a
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bit what is you say are used to javascript uh to to teach it to j. v. m. transfers
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uh maybe uh so those are the idea would be to store the output of one of
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the compiler faces and uh based on that we can jack restart accomplish and from that point on
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uh but well when we put this thing in the compartment parents
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so expensive that have to show you the compiler pipeline uh so
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you thought we've some source kind of fire and then that night
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it happens and in the end you get one or more classifiers
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ah so now we need to get a beep beep into the magic to expand
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what's going on so first thing is we're going to prospect find it into the tree
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oh what does that mean are so i start by rushing yards
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am pressing an expression like up here is an expression uh the
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process was going to say to see that and say okay that's
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that's an identifier and the the identifier is via the string option basically
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uh and then if i do hope that it and then the parser because of uh don't know that this is some kind of
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selection so that's reprinted with a select tree not which takes the
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uh thing we prosper option and then set x. m. out of its
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and then if i but parents and put some
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constant here then this becomes an application of something which
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is represented with the pipeline that uh which has a
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second parameter takes a literal which is a constant five
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okay so so that makes sense but um once you have these three
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uh what can you do we feed you can't really do anything with
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it yet 'cause it's a only syntactic it doesn't have any semantic information
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until like what the code is doing so the next step the bits that
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is type or which is like taking this pen type tree and type
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checking it um and the way tech checking walks i'm not going to explain
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lack of details 'cause that many many more towards wharf of material but
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uh we start at the top of the roots so we have already prostrate
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and to check check apply first we need to type jacket children something to type check select
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and tactics selected type i don't and to type i don't we know all this is an identifier
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uh for option so at this point we have some information about that
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scripts we know what's uh and names we really have no parents a source file
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we know what's on august buff and based on that we can say that a lack
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of dish in this context results to it that up for example and uh here on
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the train the details but basically i have has another tree like structure tree present types
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uh but you understand refuses a that option but really the compiler is going to like make up some
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uh some type for a and then he's going to make up some type for selecting opt out of a
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ah ah so okay now we have the type of or if and we can go back up one level to try to select
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so to to select we need to look for some the element some for some uh if you
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could tell them in a that much and it's going to get a type like maybe into two int
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and once we have this information we can then uh
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type apply not by a first typing for a constant five
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and the type of five these five because we have singleton types fortress
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and we know when we can just varies you see that by applying this thing to that think we must get
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and since i'm unveils one very big thing i've crossed over here is that taking can
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also create new trees so uh as you're probably familiar right for right lists of one two
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then um this is going to be current writing does that apply of one two and the way this
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works is uh when i'm type checking you just so this is jack and apply now that we've seen before
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and then uses some identifier and one sector checked it i'm going to look at the
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expected type and expected type is something that must be applied and we know this because
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we're coming from and apply not so because of this the compare are you going to
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say okay i have to introduce but don't apply here to be able to take checklist incorrectly
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and there's many many ways in which the type checker can create new trees and like
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that of course uh most important when instead i just implicit resolution up to get resolution uh
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so for access that max uh when we get to when you have seen that three
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looking for is going to say well this is actually an effort that takes some uh
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a given parameter something physical matter and i'm just going to give it
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shows you doing to resolve that parameter is going to create a tree forts
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uh and the other important thing to note is that for this is an
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item button process so if we take this tree which has been typed ones
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and if we try to retake it again to compare is not going to keep inserting new trees except
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you there's a bug in the new does that apply to the top rated at plenty that happen before um
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and this is going to be very important for what i'm going to freighter but it's already
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very very useful as a concept for debugging because it means about as uh we go full compare
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faces and we start transforming the trees we can always like sanity check that what we're doing makes
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sense by redoing the type checking and a very
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fine but indeed or four types much art correct
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ah okay so i know we've seen like the biggest piece of the pie are and
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novell as we can replace the magic by the actual the rest of the compare um
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so i'm going to explain what is things do so picture is uh
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in something that's exist within scare twins carefree
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and the the original motivation is separate computation so
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if you uh just produce some classifier ah in your class for you're going to have
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methods in this may further to go i'm going to have types this times are going
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to be j. v. and types like a variety stuff into that j. v. m. type
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is going to be just because of the j. v. m. for because jarvis reports uh generates
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oh there's also some extra information but the g. d. m.
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doesn't choose but but jealousy uses to um to get type parameter
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information so at some point somewhere in that class i will write all this may for that we say returns a list actually it
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returns a list of int uh but but we can isn't doesn't
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support of course all this cut types because colour has many more
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sort of types that java has an particularly could have higher kind
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it types union types or that kind of stuff so uh huh
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we need to store this information somewhere in the classifier
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all around uh where we can use it because uh if
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i can prior to fires a that's going be that's gonna um if i've once i've i'm done comparing a that's correct
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i start comparing be that's colour with the results of the first completion on the cusp of any to nova types
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of but the skeleton pirate uh used for the first thing
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i can quite so this information is the chicken information which is
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towards in the class fines gonna to and i'm going to explain how it's stored in the t. v. uh in a few minutes
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ah so picker itself is not going to transform any three it's
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just going to like not information and story to a a site and
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then it's going to take the trajectory and proceed to the next
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phase and i see next phase it's actually next fifty phase uh so
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all of this a small faces are going to take this very high rather
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your subject re we have which represents a oscar program and beat by beat
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we're going to transform them into something which can be run on the j.
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v. and on some of our backend and once we've done all this simplification steps
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uh we get to the back and uh and which uh back unjust civil a piece of code which is
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going to take or trees and when to emit classifiers
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for them or j. was create a or something some morphine
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okay another question is uh among all these things are where should
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we put out a obvious new intermediate representation that we want to store
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and of course i put it in the middle it's the picker and because at
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when we are at the peak or phase we're just after we've type check trees
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which means we have all the semantic information needed to understand what opera one has to do
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but we we haven't yet done all the simplifications which
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uh eventually allow us to run on a some specific a run time
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so are well what we put in his fight
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exactly what what's the point so the first main parties
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is something that can be that should be able to evolve as we go forward news conversions we have new ideas we
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find things that didn't really work out we want to be able to add
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stuff we move stuff or not we remove stuff but the cricket stuff without
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breaking existing uh files and has to be as compact as possible because
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this this files are going to be in every jar you distribute so
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uh we try to make the comp formats uh something that does not have a
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huge overhead and it has to present all the information you need for computation so you
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you need to be able to take the test devalues inputs and get to have
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the same thing that you would have gotten if you had started from those four stars
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um hum and then as long as we're doing of that maybe we can add some
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extra information that can be used for putting like i. d.s rappers documentation generation et cetera
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okay so now i'm going to expand uh the binary format of tasty in some details and to make
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that is boring i'm going to use recognise diagrams ah
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so the first thing is is awesome constant which uh
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is how you see that the fight is it tasted fine and after that um of and the next
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two thing are are reprinted isn't natural numbers and i'm going to show which encoding we use for natural numbers
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and the result the module version and the mind of irrational format and like the v.
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n. gory is a vision is going to be fixed for like the next uh a century
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and uh we can just increment minor version without breaking competitive it
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and after that comes the name table which is where we store all the names that we're going to
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refer to you know program and after that comes a bunch of sections which uh uh where we actually
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put the uh type checked abstract syntax trees but what's wait that's why it's called tasty and in expand
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formation we want so there can be one or more the sections you should where you have this rip here
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um so the name table is just a you need to when uh
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when you encoded you have to choose like you have to write than
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its strength and then you just right and a bunch of names and
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then it's a interesting that's not not just like a bunch of uh
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of string constants but the height can have some semantic information
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so uh have you have a just basic names which are
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just like a bunch of you to have a good points
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then you have some more interesting things equity financial for example sometimes
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we need to to represent a scanner that hints and we could were present it as a string
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we have of the dot is how we we see that
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this is actually preferred things but the this is pretty problematic because
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i become very hard to distinguish between the names uh that have meaning
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but but the compiler uses and the name but we use or then
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especially instead are where you can but pretty much anything you want in
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the names of the definition if you just enclose them in tactics um
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so pretty fine name is represented using some some
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tax abuses some constant uh then the uh some length
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information and then um just to some part of the pretty fire so in this case it would discover
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and the thing your selecting which and in this case would be ins and then wife is just going to be a a
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the natural number uh if you're going to the end of set in the name tabor solicitous i'll just pointers to or fix
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okay and now we get to the meat of the tasty format
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the tasty meat uh which is the obstruction textures section so it starts
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with a string which is interesting is going to be an index in
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the name table but you get it and then a bunch of statements
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and statements and i'm going to show them 'cause there's a
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bunch of them but those are basically the trees ah of um
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of the format so you can have a package tree to
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present a package and import tree a tree for defining a vile
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and uh those are very close to how they're represented internally by
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the compiler so for example of art is something which has a name
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it has a type it may or may not have the right hand side because it
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might be abstract and you can have many fire like pride that uh that kind of thing
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and um then the other important part is type spencer's so
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uh types uh there's also a lot of them and you might
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have guessed a but a few interesting ones but you might
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recognises tight bounds so this is like when you're right so prototype
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of something so type of something we are present that we've uh type pounds
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a tiger followed by a have a representation of your balm for better presentation of the
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higher up and the type applications actually just of int that's represented with and apply type tyke
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uh have a presentation of priests and denver presentation of its arguments which can be easy all of them all
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and then turns so that's very close to what we've seen before we d. i. denton select nodes
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uh but here we are at the root of it of the tasty formats so it's a beach or novel
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uh and here there's an interesting uh an important points that's not very obvious is that not
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all of the terms have types but when type language so what does that mean so in
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fact to uh avoid wasting space we don't need to starve the types of everything because we
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only to screen to store the types of the leaves of the trees so for example the identifiers
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once we've uh looked up in the scripts what are the what do they
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represent we can still that information in the type of the i don't like
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uh but when i do an application i don't need to store the result of the type of the application because
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when i'm going to read the tasty tree i can just look at the type of a function
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the type of its arguments and then i can really a reef find again the type of the application
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and now we get to the extra sections
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which are uh after the obstruction texture section so
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uh it's very simple one that very useful when it's just the common
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section which is going to store a every scared documents in your file
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and the way this works is um before every command for going to
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store of a pointer to which definition in the uh t. c. uh our
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to stay for you it refers to another and for the command the a set of a cut points
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which are present the string of the commands and then the position of this convention this was fine and this
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information is completely use us for compiling of course but it's really useful if you're an id and you want
00:23:04
to shoot to user of the uh the comment the
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documentation comments for the thing you he's hovering over and
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uh we also using it for example in the dirty wrapper where you can type
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court and dock space than the name of some method is going to look at
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the documentation comment from the tasty fire and that's a much more direct way than going from
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like get inverse source jar a processing unit and trying to matt much
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that we've uh have a look at the trees you have in your compare
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and finally a very important section is the position section which stalls
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the position so the offset from the beginning of the fight of every tree that has been
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written by the user i say user recently because as we've seen before when you type checker program
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you're going to uh create new trees which are not written by the users and so this trees
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uh you need to be able to distinguish them from those but the user what because when you
00:24:08
holder or something in your idea for example you want to see the type of uh
00:24:13
the thing that's written down and not the type of the syntactic thing to compare our uh
00:24:18
put on top of your current and this uses um pretty interesting data encoding that i'm not
00:24:24
going to detect 'cause it's a bit complicated uh but you can see the for grammar we've
00:24:29
an explanation of these in the just the format that's graphite in the dirty repository
00:24:35
okay cool but yeah what can you do with that stuff
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and so they're completely uh we can start with the program
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i have a library a which is compiled it's gonna for that one i want to use it which colour for the two
00:24:48
uh how they do that to a white for the coffers of library kate to uh we probably should
00:24:54
first coffee that too i can do that otherwise i found very impatient i could fetch a draw for a
00:25:01
did we classifies cause very they don't uh matter and just
00:25:05
regenerated then from the t. c. friends which are also in the
00:25:09
jar uh and of instead of doing that by hand you could
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imagine viterbi tool can automatically do that in the same way that
00:25:18
when you're working with uh be true but what some sources it's
00:25:22
going to automatically fetch resources and compare them and question for you
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you'll be too could fetch her tasty can can can compare them and catch them for it
00:25:32
um or and that's a an it yeah i hadn't
00:25:35
thought about that jason's like a proposed a few days ago
00:25:39
you could imagine that you have something like maven or me or
00:25:42
from a van that uh i can automatically uh from the um existing
00:25:48
jobs published nave and create new jobs we've updated classifiers which i
00:25:53
think would be pretty cool 'cause it means that this would work with
00:25:56
any between you want even and uh of course this isn't really is a civil but this is only going to war
00:26:05
either stolen liberate off with the two is designed to be compatible with the standard library
00:26:09
of free that one the kind of things that this can hopefully if is if it's
00:26:14
for example in skin africa to we change again even couldn't have traits for some weird
00:26:18
reason or if we change any of the details of uh how we encode things uh
00:26:26
after type checking and before um cut generation
00:26:30
so you could say okay well i could do that or i could use for
00:26:35
the source files and compare everything from sources um and that's pretty much the same then
00:26:42
but it's not really the same because uh when you're using source files you then you
00:26:47
don't have binary compatibility as a parameter of source compatibility in particular when you upgrade corruption
00:26:54
uh because the type check or a virus and because type inference is so performance collides
00:27:01
a possible sometimes such a problem stop start checking out does something slightly different just because
00:27:06
type in france now wants you in the different way uh you don't have
00:27:11
this problem when you use tasty because it is the trees after type checking
00:27:15
which means we have resulted in peace it's we have inferred all the types
00:27:19
we have result we overloads so all this kind of things which can like
00:27:24
change depending on what the compare decides to do with record your words are not going to change
00:27:31
ah so so tasty of course uh if it was just it is a binary format you
00:27:37
couldn't really do anything useful if it but we have some green around it which makes it much
00:27:41
more useful so first we kind of course generate testifies and that's super is you just take
00:27:46
a dirty uh you can buy stuff and next will that classifies is going to make the tasty
00:27:50
files and and then you can also compiled from the t. c. files directly ah using dash
00:27:58
from deaf tasty when you run a computer you can also declined fire and the combining basically means
00:28:04
taking the tasty trees and then pretty pretty neat and that can be done using the dirty comply
00:28:10
flag i'll just by opening the testifies in his code when you have the dirty pretty in stuart
00:28:17
ah okay and so so far testes
00:28:21
basically the internal format used by the t.
00:28:24
but we have a brother brother like bigger ends and that we wanted to be evil
00:28:30
format for intermission presentation of of star and to provide this can be done uh
00:28:36
there's a approve of concepts gonna to plug in um we work last year
00:28:41
that can take a scared to trees and convert but convert them into tasty
00:28:46
um and so far um it's just there's been a proof of concept but
00:28:52
would like to like try to get this into more user state and the um
00:28:58
the men remaining or a technical issue to fix to do that is just to move that or
00:29:03
the logic i want testing which is currently like part of the t. itself into its own projects
00:29:08
which will cross compile between skirt wins carefree and uh once
00:29:13
we have that we can also think about doing the other direction
00:29:16
where we take the tasty files and produce a and skirt was
00:29:20
able to understand and and can do that that means you could
00:29:24
use the t. i. reason schedule projects of course if there's like a big asterisk here does act
00:29:30
many things that need to be taken into account to make sure that this
00:29:33
is possible but in principle this is something we can achieve i think um
00:29:40
okay and it's another to see nevada my phone okay well should i use
00:29:44
this a tasty thing to be tools and the answer is like most of
00:29:49
a lot actually need to cause there's these uh different but very much related
00:29:54
thinker just reflect a which is going to be easier to use because directly
00:29:59
manipulating does the trees is not easy uh whereas this year effect is something that
00:30:06
um if we're reserve menus cases replacing scared to macros and provides
00:30:11
an a. p. i. which is similar to stretch mark was where your
00:30:14
i'm manipulating trees uh using um i was a library but
00:30:20
uh it can also be used for for putting because of the
00:30:23
trees but this year effect uh exposes a whereas in a skirt too
00:30:29
the um a creepy i exposed basically the other compare intern ours these three factors
00:30:34
to expose something which matches the tasty spec which means it should be something that
00:30:38
can be evolved and something which you can rely on for tuning in particular are
00:30:44
are we wrote um that tasted to that
00:30:47
semantic d. b. um in transpire basically which
00:30:52
warps are using which is implemented using taster effect instead of like as a compare phase or
00:30:58
something which directly reads tasty treats and uh we also have a work in progress implementation of
00:31:05
which takes that testifies and generate h. t. m. l. documentation so it's got doc replacement basically
00:31:11
and that's very interesting because if you start from the tasty to
00:31:14
generate your documentation instead of starting from sources then that means documentation
00:31:19
generation much faster because you don't have to type figure who program
00:31:22
just to uh be able to generate h. t. m. l. i'm not
00:31:28
and for more information you should go see a new crest or commit up wanting to more
00:31:34
ah thank you very much
00:31:46
if or uh
00:31:52
so what it sounds like you could take the t. c. files
00:31:57
unpack them into the jars to put up on the report
00:32:01
yes isn't them understand so when you buy the for twin you
00:32:06
you can post a fee for the comparative into get both actress and testifies in the same output directory
00:32:12
and they're going to be part of the jar you that gets published because of the second fall on 'cause if you can
00:32:18
make a pretty print a image of what we did to the compiled code
00:32:24
isn't that the that you need to do obviously sure something to keep people screwed
00:32:29
yes so if you well so when you when you have java byte code
00:32:35
already like very close to source and you might want to fixate but if you
00:32:38
really don't want to share your current and in the same way that we've stacey
00:32:42
you pulled obfuscate either that's a pretty complicated instead what you could do is just
00:32:48
and not free you probably will offer is a way to to not generate before tasty trees we've already implementations
00:32:54
but just generate enough information to get to the types of all the difference
00:32:59
in a program which is the the bare minimum needed to do separate competition
00:33:05
and the uh but that's not enough to things like in lining where to in
00:33:09
line with what you need to actually get a cut the button fight for example
00:33:12
but for um a lot of other use cases you don't need to for information
00:33:17
of tasty and we could have a mode where ever compare doesn't generate this information
00:33:23
okay
00:33:29
hello to him oh what what do you do uh i mean this
00:33:34
colossal misuse of lime jello letters right so uh_huh be also is too or
00:33:41
which version of the judge and the u. k. um
00:33:46
so no so it's true but if you like if
00:33:50
you write your on library that uses a specific version
00:33:53
objectives discussed a lot every so these comparative java twelve
00:33:58
you won't be able to use it in your project we've a java eighth
00:34:01
easy if it's uses a a new methods which have introduced since java eight
00:34:08
ah we meet there might be a a good do um a good point that we should have
00:34:15
the food in the tasty which reference which version of the j. d. k. we are compiling against
00:34:20
but in general this is the same you should have with any dependency actually if you use
00:34:25
some specific version of a dependency then everything but depends on you need to use at his discretion
00:34:38
yes i'm starting tooling project right now should i focused on bass or semantic the the or
00:34:44
would you use cases should i choose one or the other uh it depends on what kind of
00:34:51
three new interesting so the like the the binary formats themselves some
00:34:55
probably not what you want to focus on you want to focus on
00:34:58
what does mediate guys to do the things i want to do so ah
00:35:02
acts committed is is semantic d. b. as um a way to store information
00:35:07
but the the interesting part is more like the a. p. i. is let's go undetected
00:35:10
you to do cool stuff and if this like you guys are uh what you what
00:35:16
works the best for project then you should use that um well
00:35:20
if you are more interested in doing something that's uh we that can
00:35:24
use a new features of cafe for example then our uh maybe
00:35:28
you can try using tissue effect instead and so it depends a basic
00:35:40
a new one example you explain that uh you still have twos well
00:35:46
standard library compatibility issue like when you said okay i read you some stream
00:35:51
in three point two yeah how is this going to be sold or
00:35:55
it is a tool and what are your plans to to do that
00:35:58
yeah so the the should be if um if someone is gonna three point two decides to to
00:36:04
change the name of of just to something else 'cause we do in fact the name and like that
00:36:10
that uh that would be very hard to to make compatible
00:36:13
it it's not impossible to imagine some way to paper over what
00:36:16
kind of things but i think what we'd like to do instead
00:36:20
you just have more discipline thing okay now that we have um
00:36:24
two in view of the ways to but maintaining binary compatibility is for like
00:36:30
many years it is a possibility we just need to
00:36:33
be a more strict in how we evolve discussed another library
00:36:39
so uh like not redesign it every two years
00:36:44
which i think people will also appreciate
00:36:49
uh other questions
00:36:54
uh_huh
00:36:58
you know the kind of related question like have you discussed using java nine modules
00:37:03
uh_huh could've paper ever that difference by just saying okay well this is what it depends on its
00:37:09
colour to eleven this much it depends on the kind of the the same me you you space that
00:37:15
yes only use like it java compatible you could be i just between themselves and lose colour
00:37:21
yeah that's exposed to him like you could kind of make you would kind of make that forecasts but it's
00:37:27
uh you have a hard parties you can extract isolated thing is using the on castro does or whatever but then
00:37:34
when you did them to interact it gets it gets complicated and
00:37:38
i mean people have been trying to do what we've twenty like for twenty years we factor is g. i. and i don't think it
00:37:44
uh right that's satisfying yet yeah
00:37:57
uh oh would it be like uh in the realm of possibilities to like uh
00:38:02
yeah he's taste is a target for or java or
00:38:05
in other languages yes you could automatically he'll use uh
00:38:11
java libraries colour g. s. are native stuff like
00:38:14
that so it's it's uh i think it's uh
00:38:18
it's possible you'd have to extend tasty somewhat maybe for some of the features of languages
00:38:24
that couldn't be expressed in sky but i think it's a a very interesting thing to
00:38:27
explore because it's true but if you can even if your like your wage writer you make
00:38:33
your own language if you can use tasty as a back can then you get a lot
00:38:37
of things for free you gets a super optimist j. s. backend j. d. m. a native
00:38:44
uh eventually and you can use libraries from the sky consistent
00:38:49
uh and actually norman's current too so it's uh i
00:38:52
think it's a very interesting thing to that could be explored
00:39:03
oh so it is suggested that people cool little should i use features
00:39:10
conversions to become palpable stacy files uh_huh and does that mean the skeleton panel
00:39:16
and we need something that completely exceed full does for the semantics of what
00:39:20
it takes to do little that's the feature there's an excel does that constraining possible
00:39:25
yes it's a radius yeah there's or is this
00:39:28
a tension between like recording things and keeping compatible
00:39:33
and uh that's why i pointed to a a schedule yes which
00:39:38
full react uh the lifetime of the zero point six areas
00:39:42
has maintained competitive for their on uh uh internet or presentation
00:39:46
we're still evaluating it and then you have to work a bit harder to be able to do this like you have to
00:39:54
uh reinterpret old versions of fire is in the new way you
00:39:58
you want things to be done but i think it can be done
00:40:01
for for the things we've one we would like to do for this
00:40:13
who who's done correctly that the binary compatibility is only
00:40:17
on taste meaning if you have a cello on i agree
00:40:20
consume your skull every and you're updating inversion scholar that'd make break yeah yeah the the um
00:40:28
see it when when i say binary compatibility it's a bit weird because what was
00:40:32
binary mean uh like castle classifies a binary is the taste is also binary so
00:40:38
to be clear of as a uh we we would maintain tasty compatibility but not binary compatibility
00:40:45
but then uh evan your job project will be able to uh make
00:40:50
use of uh we compiled classifiers to but for compared with the new version
00:40:57
uh but this project censored would not be recompiled uh from to see if they don't output
00:41:02
easy unless someone makes a taste for java a tasty backend for java which will be cool
00:41:12
i have two questions one is a really do cross compilation has its beauty
00:41:17
like you know you want to target to say to love and that one
00:41:21
uh_huh well that looks good things a little bit different designs uh it's just want this but that's one question uh this uh
00:41:30
a little production that's it we have been and into this
00:41:33
duty to compatibility issues it uh_huh just get last is i
00:41:37
would would that be a bit of a colour like you know let's say lose it is to file but uh that
00:41:44
no new listeners quality but uses a different version of g. t. k.
00:41:48
is that of the to recover from it i will only come or so c. d. eat it
00:41:54
really depends like if if ah like say discuss
00:41:58
another very is compiled against a new g. d. k.
00:42:02
but it doesn't use any of the new features of a. g. n. u. v. new methods for example
00:42:07
then you might still be able to re compile but to give that a baker
00:42:12
ah uh if it does use directly methods inject there's not much you can do the 'cause
00:42:18
even if it does it exist in the g. d. k. version you're trying to use an
00:42:25
and your for your first question and you when you cross compiler you'd see won't we
00:42:29
meet a two different tasty files uh if say in the new version of the compiler
00:42:35
you you generate to you have a different way of representing phase
00:42:39
wreck you you need somehow to stories in a in a different five
00:42:43
and this cruel this would have to where you
00:42:47
could imagine a putting everything in like one big jar
00:42:52
ah and using something like what java support for you can put check different versions
00:42:59
of classifies indifference subdirectory is based on the new version of java better using you can
00:43:04
like eight slash aided class nine slash aided stress in the same drawer and then
00:43:09
one of them is going to be right but you're right and you're probably john wayne
00:43:13
we could maybe have something similar for t. c. files in a
00:43:16
jar depending on this conversion ah not sure how useful that would be
00:43:23
the uh one last question
00:43:29
oh
00:43:32
uh_huh i'm how to work with its colour features that maybe
00:43:36
don't exist uh the previous versions so so you have a tasty
00:43:41
a file you compile with three uh_huh uh i do use union types uh_huh
00:43:47
but you want to use it later to twelve version yeah push good question so
00:43:52
the reading tasty from uh ask uh two has a bunch of gender is in
00:43:57
one of the measures that the oddity features that don't exist instead to so you
00:44:01
have to go on a case by case basis some of these features you can emulate
00:44:06
uh some of them maybe we had some like the minimum amount of project we need in
00:44:12
that uh like for the next national skirt to to make them usable and some of the users
00:44:17
if you try to to use them they just one for collective so compare are we to do like you can
00:44:22
choose this method firms get too because it uses a match type and i don't know how to interpret much types
00:44:29
ah so then a library designer when lighting like the public a. p. i. of there are a
00:44:35
library would have to be careful to read or write things which can be a interpreted by basket winfrey
Conference Program
A Tour of Scala 3
Martin Odersky, Professor EPFL, Co-founder Lightbend
June 11, 2019 · 5:15 p.m.
8340 views
A story of unification: from Apache Spark to MLflow
Reynold Xin, Databricks
June 12, 2019 · 9:15 a.m.
1271 views
In Types We Trust
Bill Venners, Artima, Inc
June 12, 2019 · 10:15 a.m.
1569 views
Creating Native iOS and Android Apps in Scala without tears
Zahari Dichev, Bullet.io
June 12, 2019 · 10:16 a.m.
2233 views
Techniques for Teaching Scala
Noel Welsh, Inner Product and Underscore
June 12, 2019 · 10:17 a.m.
1296 views
Future-proofing Scala: the TASTY intermediate representation
Guillaume Martres, student at EPFL
June 12, 2019 · 10:18 a.m.
1159 views
Metals: rich code editing for Scala in VS Code, Vim, Emacs and beyond
Ólafur Páll Geirsson, Scala Center
June 12, 2019 · 11:15 a.m.
4697 views
Akka Streams to the Extreme
Heiko Seeberger, independent consultant
June 12, 2019 · 11:16 a.m.
1552 views
Scala First: Lessons from 3 student generations
Bjorn Regnell, Lund Univ., Sweden.
June 12, 2019 · 11:17 a.m.
577 views
Cellular Automata: How to become an artist with a few lines
Maciej Gorywoda, Wire, Berlin
June 12, 2019 · 11:18 a.m.
386 views
Why Netflix ❤'s Scala for Machine Learning
Jeremy Smith & Aish, Netflix
June 12, 2019 · 12:15 p.m.
5030 views
Massively Parallel Distributed Scala Compilation... And You!
Stu Hood, Twitter
June 12, 2019 · 12:16 p.m.
958 views
Polymorphism in Scala
Petra Bierleutgeb
June 12, 2019 · 12:17 p.m.
1113 views
sbt core concepts
Eugene Yokota, Scala Team at Lightbend
June 12, 2019 · 12:18 p.m.
1656 views
Double your performance: Scala's missing optimizing compiler
Li Haoyi, author Ammonite, Mill, FastParse, uPickle, and many more.
June 12, 2019 · 2:30 p.m.
839 views
Making Our Future Better
Viktor Klang, Lightbend
June 12, 2019 · 2:31 p.m.
1682 views
Testing in the postapocalyptic future
Daniel Westheide, INNOQ
June 12, 2019 · 2:32 p.m.
498 views
Context Buddy: the tool that knows your code better than you
Krzysztof Romanowski, sphere.it conference
June 12, 2019 · 2:33 p.m.
394 views
The Shape(less) of Type Class Derivation in Scala 3
Miles Sabin, Underscore Consulting
June 12, 2019 · 3:30 p.m.
2321 views
Refactor all the things!
Daniela Sfregola, organizer of the London Scala User Group meetup
June 12, 2019 · 3:31 p.m.
514 views
Integrating Developer Experiences - Build Server Protocol
Justin Kaeser, IntelliJ Scala
June 12, 2019 · 3:32 p.m.
551 views
Managing an Akka Cluster on Kubernetes
Markus Jura, MOIA
June 12, 2019 · 3:33 p.m.
736 views
Serverless Scala - Functions as SuperDuperMicroServices
Josh Suereth, Donna Malayeri & James Ward, Author of Scala In Depth; Google ; Google
June 12, 2019 · 4:45 p.m.
936 views
How are we going to migrate to Scala 3.0, aka Dotty?
Lukas Rytz, Lightbend
June 12, 2019 · 4:46 p.m.
710 views
Concurrent programming in 2019: Akka, Monix or ZIO?
Adam Warski, co-founders of SoftwareMill
June 12, 2019 · 4:47 p.m.
1975 views
ScalaJS and Typescript: an unlikely romance
Jeremy Hughes, Lightbend
June 12, 2019 · 4:48 p.m.
1377 views
Pure Functional Database Programming‚ without JDBC
Rob Norris
June 12, 2019 · 5:45 p.m.
6389 views
Why you need to be reviewing open source code
Gris Cuevas Zambrano & Holden Karau, Google Cloud;
June 12, 2019 · 5:46 p.m.
484 views
Develop seamless web services with Mu
Oli Makhasoeva, 47 Degrees
June 12, 2019 · 5:47 p.m.
785 views
Implementing the Scala 2.13 collections
Stefan Zeiger, Lightbend
June 12, 2019 · 5:48 p.m.
811 views
Introduction to day 2
June 13, 2019 · 9:10 a.m.
250 views
Sustaining open source digital infrastructure
Bogdan Vasilescu, Assistant Professor at Carnegie Mellon University's School of Computer Science, USA
June 13, 2019 · 9:16 a.m.
376 views
Building a Better Scala Community
Kelley Robinson, Developer Evangelist at Twilio
June 13, 2019 · 10:15 a.m.
245 views
Run Scala Faster with GraalVM on any Platform
Vojin Jovanovic, Oracle
June 13, 2019 · 10:16 a.m.
1342 views
ScalaClean - full program static analysis at scale
Rory Graves
June 13, 2019 · 10:17 a.m.
463 views
Flare & Lantern: Accelerators for Spark and Deep Learning
Tiark Rompf, Assistant Professor at Purdue University
June 13, 2019 · 10:18 a.m.
380 views
Metaprogramming in Dotty
Nicolas Stucki, Ph.D. student at LAMP
June 13, 2019 · 11:15 a.m.
1250 views
Fast, Simple Concurrency with Scala Native
Richard Whaling, data engineer based in Chicago
June 13, 2019 · 11:16 a.m.
624 views
Pick your number type with Spire
Denis Rosset, postdoctoral researcher at Perimeter Institute
June 13, 2019 · 11:17 a.m.
245 views
Scala.js and WebAssembly, a tale of the dangers of the sea
Sébastien Doeraene, Executive director of the Scala Center
June 13, 2019 · 11:18 a.m.
662 views
Performance tuning Twitter services with Graal and ML
Chris Thalinger, Twitter
June 13, 2019 · 12:15 p.m.
2003 views
Supporting the Scala Ecosystem: Stories from the Line
Justin Pihony, Lightbend
June 13, 2019 · 12:16 p.m.
163 views
Compiling to preserve our privacy
Manohar Jonnalagedda and Jakob Odersky, Inpher
June 13, 2019 · 12:17 p.m.
302 views
Building Scala with Bazel
Natan Silnitsky, wix.com
June 13, 2019 · 12:18 p.m.
565 views
Diversity and Inclusion Panel: Bring the Thunder!
Panel
June 13, 2019 · 2:30 p.m.
245 views
Asynchronous streams in direct style with and without macros
Philipp Haller, KTH Royal Institute of Technology in Stockholm
June 13, 2019 · 3:45 p.m.
304 views
Interactive Computing with Jupyter and Almond
Sören Brunk, USU Software AG
June 13, 2019 · 3:46 p.m.
682 views
Scala best practices I wish someone'd told me about
Nicolas Rinaudo, CTO of Besedo
June 13, 2019 · 3:47 p.m.
2713 views
High performance Privacy By Design using Matryoshka & Spark
Wiem Zine El Abidine and Olivier Girardot, Scala Backend Developer at MOIA / co-founder of Lateral Thoughts
June 13, 2019 · 3:48 p.m.
754 views
Immutable Sequential Maps – Keeping order while hashed
Odd Möller
June 13, 2019 · 4:45 p.m.
278 views
All the fancy things flexible dependency management can do
Alexandre Archambault, engineer at the Scala Center
June 13, 2019 · 4:46 p.m.
390 views
ScalaWebTest - integration testing made easy
Dani Rey, Unic AG
June 13, 2019 · 4:47 p.m.
468 views
Mellite: An Integrated Development Environment for Sound
Hanns Holger Rutz, Institute of Electronic Music and Acoustics (IEM), Graz
June 13, 2019 · 4:48 p.m.
213 views
Closing panel
Panel
June 13, 2019 · 5:54 p.m.
400 views