Interview with Jon Pretty

hello everybody i'm alexis kraborf the hello everybody i'm alexis kraborf the organizer of sf scala and here with us organizer of sf scala and here with us we have a very special guest john priti we have a very special guest john priti who is one of the most experienced who is one of the most experienced scholar veterans scholar veterans uh he uses scala since 2004 and in paul uh he uses scala since 2004 and in paul phillips's famous quote it took him to phillips's famous quote it took him to 10 years to gain 10 10 years to gain 10 years knowledge of scala which is most years knowledge of scala which is most impressive uh and a very very paul did impressive uh and a very very paul did add that it took him i think about two add that it took him i think about two years to get the same amount of years to get the same amount of experience right we're going to ask him experience right we're going to ask him next time when he will apologize that's that's great to have you with us that's that's great to have you with us we have a uh uh job previous is talking we have a uh uh job previous is talking today about uh rapture and we're gonna today about uh rapture and we're gonna do a workshop and follow along uh but do a workshop and follow along uh but first i will welcome you here thank you first i will welcome you here thank you it's great to have you with us here it's great to have you with us here thank you for the kind introduction and thank you for the kind introduction and uh obviously uh obviously uh it's not very uh it's not very often we meet somebody who did so much often we meet somebody who did so much scholar and uh and some from so early so scholar and uh and some from so early so maybe you can tell us how did you maybe you can tell us how did you discover scala what interested you in it discover scala what interested you in it and what kept you in it for for all this and what kept you in it for for all this time time so i i discovered it so i i discovered it back in back in summer 2004 summer 2004 and and i was i was setting up a business with a i was i was setting up a business with a with a friend of mine we wanted to with a friend of mine we wanted to develop our own language we had develop our own language we had aspirations that were aspirations that were completely infeasible but we wanted to completely infeasible but we wanted to create our own language create our own language and and as part of as part of the the research as part of as part of the the research you ought to do before embarking on a you ought to do before embarking on a large project like that we we sort of large project like that we we sort of looked at what was out there already and looked at what was out there already and i stumbled across this website from uh i stumbled across this website from uh epfl mm-hmm epfl mm-hmm and uh it was it was my my business and uh it was it was my my business partner who was the brains behind it so partner who was the brains behind it so i i i said to him have a look at this i i i said to him have a look at this this this sounds like this this sounds like how do you stumble how do you stumble how do you stumble how do you stumble upon something like fpfl.c i i googled upon something like fpfl.c i i googled google i think google was was there yeah google i think google was was there yeah okay 2004 yeah yeah okay 2004 yeah yeah and uh yeah i found this found this and uh yeah i found this found this language okay i can't remember what did language okay i can't remember what did you google for like interesting you google for like interesting languages languages i must have searched for functional i must have searched for functional functional and presumably object-oriented i i can't presumably object-oriented i i can't remember remember maybe it was just programming languages maybe it was just programming languages i went through a list of i went through a list of 50 well 50 pages worth of of all the 50 well 50 pages worth of of all the languages out there languages out there and somewhere somewhere there was scala and somewhere somewhere there was scala i'm sure it wasn't on the first page i'm sure it wasn't on the first page because it was it was only uh like three because it was it was only uh like three or four months after it was first or four months after it was first announced interesting announced interesting but uh but uh we tried it out we tried it out we we compared it to a language that was we we compared it to a language that was um um it was around at the time called nice it was around at the time called nice nice nice i have no idea what happened tonight but i have no idea what happened tonight but we i remember it we i remember it we we did some tests and the choice was we we did some tests and the choice was between nice and scala okay and we went between nice and scala okay and we went with scala and uh with scala and uh so skull was not nice so skull was not nice scala was not nice it wasn't nasty most of the time it wasn't nasty most of the time but uh yeah we were then building but uh yeah we were then building the the the business plan remember this the the the business plan remember this is this is this is two guys fresh out of is this is this is two guys fresh out of university without any real world university without any real world experience experience our our plans were to to develop our our plans were to to develop a language or or some technology that a language or or some technology that was that interested us was that interested us funding that through some consultancy funding that through some consultancy work work now as as a as a startup um now as as a as a startup um without an experience without an experience what we ended up doing was spending all what we ended up doing was spending all our time our time working for no money on on a few working for no money on on a few web projects sounds like that's that's web projects sounds like that's that's san francisco startups san francisco startups maybe we said there's no investment maybe we said there's no investment involved involved this this is this is england right yeah this this is this is england right yeah we uh we uh not happens not very common thing here not happens not very common thing here either right right yeah so so we were either right right yeah so so we were building websites in scala building websites in scala we we ended up having the first we we ended up having the first what what could be called the first what what could be called the first commercial commercial piece of software written in scala piece of software written in scala and and i mean the experience working with it i mean the experience working with it back then uh this this was scala 1.3 back then uh this this was scala 1.3 it was um it was um it was very pleasant most of the time it was very pleasant most of the time and then occasionally we'd stumble and then occasionally we'd stumble across some bug across some bug that absolutely through that absolutely through everything the compiler would fail to everything the compiler would fail to compile it would crash compile it would crash for no reason i mean it wasn't like we for no reason i mean it wasn't like we suddenly started using some new broken suddenly started using some new broken feature it was like we'd be doing feature it was like we'd be doing exactly the same thing we'd been doing exactly the same thing we'd been doing for the for the the first the first eighty percent of the project and then eighty percent of the project and then one line would would cause it to crash one line would would cause it to crash so there were a few occasions like that so there were a few occasions like that that were that were incredibly frustrating so it's hard to incredibly frustrating so it's hard to even imagine right like the live before even imagine right like the live before the big bang the big bang what uh what was there in 1.3 and what what uh what was there in 1.3 and what most common things most common things were missing so were missing so the thing that i use most now that was the thing that i use most now that was missing then was implicit values okay missing then was implicit values okay implicit conversions existed okay implicit conversions existed okay you could you could automatically you could you could automatically convert from one type to another if you convert from one type to another if you put a value so that was there from the put a value so that was there from the beginning that was there from beginning that was there from from the very beginning from the very beginning uh uh i tried to have higher kind of types i tried to have higher kind of types were there in some form were there in some form i think they were there in a limited i think they were there in a limited form form um let me see let me see the the it's interesting some of the the the it's interesting some of the syntax syntax changes that were different like cell changes that were different like cell self types were there except they had a self types were there except they had a different syntax so you'd put a colon different syntax so you'd put a colon after the the class constructor and then after the the class constructor and then the type the self type the type the self type um which i quite liked as syntax and um which i quite liked as syntax and then later on that changed to the then later on that changed to the requires keyword requires keyword requires was a keyword for a while requires was a keyword for a while and then we got the current syntax which and then we got the current syntax which i always thought looks too much like a i always thought looks too much like a lambda when it's just not a lambda lambda when it's just not a lambda so i'm not a big fan of that so i'm not a big fan of that how but the collections collections well well they were they were far worse than they they were they were far worse than they are now i mean i know the collections are now i mean i know the collections get a lot of criticism uh from from get a lot of criticism uh from from certain quarters what about the api was certain quarters what about the api was they like the function names and methods they like the function names and methods the method names were the method names were generally speaking the same as they are generally speaking the same as they are now now except they were implemented only on except they were implemented only on certain certain certain types of collection certain types of collection certain types of uh certain types of uh thing like so so um you might find that thing like so so um you might find that list has a list has a sliding method but sliding method but uh actually vector didn't exist but uh actually vector didn't exist but sequence possibly didn't or something i sequence possibly didn't or something i can't remember can't remember it didn't feel intuitive because you it didn't feel intuitive because you know one thing which struck me when i know one thing which struck me when i started doing scholars is how intuitive started doing scholars is how intuitive the collection methods are and i think the collection methods are and i think personally that one of the reasons of uh personally that one of the reasons of uh adoption of scaling also spark i think adoption of scaling also spark i think really benefits from this that that is really benefits from this that that is one of the best things about the one of the best things about the collections library uh the the collections library uh the the consistency consistency or at least the the attempts at or at least the the attempts at consistency people will find places consistency people will find places where they're not consistent and that where they're not consistent and that was there in in the early days too was there in in the early days too there there was there were aspirations there there was there were aspirations to have it consistent but to have it consistent but there were many more cases where things there were many more cases where things weren't consistent weren't consistent mainly but i think by virtue of the mainly but i think by virtue of the implementation being less type class implementation being less type class okay and well in fact less inheritance okay and well in fact less inheritance based based so yeah so certain certain things so yeah so certain certain things were sporadically available on certain were sporadically available on certain collections just it wasn't consistent so collections just it wasn't consistent so how did you uh kind of uh how did you uh kind of uh i would say crystallize this color i would say crystallize this color because you wear in one of the initial because you wear in one of the initial seas of the scholar community right so seas of the scholar community right so how did you got in touch with the pfl how did you got in touch with the pfl and where did you see community grow and where did you see community grow from there right so from there right so the first i guess the first couple of the first i guess the first couple of years years myself and jamie webb my business myself and jamie webb my business partner had partner had i think i had i had no i think i had i had no um no sort of face-to-face communication um no sort of face-to-face communication with anyone from epfl i remember jamie with anyone from epfl i remember jamie who was more active than me on the who was more active than me on the mailing list back then uh had a meeting mailing list back then uh had a meeting with with martin when he happened to be with with martin when he happened to be over in the uk and they they chatted over in the uk and they they chatted about some stuff okay and uh about some stuff okay and uh we had occasional meetups in london we had occasional meetups in london though there were a few of us these are though there were a few of us these are the the the the early london scarlet the the the the early london scarlet user groups user groups meetings do they call them user groups meetings do they call them user groups did they call them it was called now did they call them it was called now it's a user group it's a user group i think didn't didn't the word meetup i think didn't didn't the word meetup sort of evolved from from meet up the sort of evolved from from meet up the company i i assumed it was it was called company i i assumed it was it was called the user group the user group and we'd meet in the pub and there would and we'd meet in the pub and there would be about be about i don't know 10 of us at most i don't know 10 of us at most and there'd be a guy there who who said and there'd be a guy there who who said well i'm i'm i'm using java i'd really well i'm i'm i'm using java i'd really love to use scala you didn't project any love to use scala you didn't project any code on screen no no no there are no code on screen no no no there are no ipads either right no ipads so so many things didn't exist back then so so many things didn't exist back then all right so you couldn't but the all right so you couldn't but the laptops were there so you could show laptops were there so you could show some code to people some code to people laptops laptops were bigger and heavier laptops laptops were bigger and heavier right right right right i think it was rare we actually i think it was rare we actually took our laptops out and looked at code took our laptops out and looked at code i think i think we were mainly just i think i think we were mainly just chatting about chatting about things we could and couldn't do and all things we could and couldn't do and all the all our favorite bugs the all our favorite bugs so you were actually kind of uh industry so you were actually kind of uh industry users right so if you follow this users right so if you follow this academic organization this mysterious academic organization this mysterious place from which skull emanated and you place from which skull emanated and you guys took it and used it in industry guys took it and used it in industry yeah we were industry users but nobody yeah we were industry users but nobody none of our clients knew we were using none of our clients knew we were using scarlet ah so we scarlet ah so we we had a few sales meetings where we we had a few sales meetings where we said yeah we're using this really cool said yeah we're using this really cool language language scala scala and i'd say call called what and i'd say call called what what what what is this so they want to what what what is this so they want to build their sites to build their sites build their sites to build their sites to auto build the back end to auto build the back end back and stuff and uh back and stuff and uh they they've never heard of scala they they've never heard of scala obviously and uh obviously and uh if if they if they did then go and look if if they if they did then go and look look on google for for information about look on google for for information about scala the fact that was so little scala the fact that was so little was it was a good sign to them that was it was a good sign to them that actually it was uh wasn't wasn't a good actually it was uh wasn't wasn't a good long-term prospect long-term prospect and that they would have had and that they would have had maintenance headaches and they're maintenance headaches and they're completely right in that decision completely right in that decision so we just told them it was java so we just told them it was java so we said we're building your software so we said we're building your software in java in java runs on the jvm it's java smart choice runs on the jvm it's java smart choice so that that yeah that's what we said so that that yeah that's what we said and uh and uh we we i think we were only really we we i think we were only really successful in in in sales when we didn't successful in in in sales when we didn't tell people it was scala and it wasn't tell people it was scala and it wasn't later until about 20 later until about 20 2011 i think 2011 i think so after after scholar solutions which so after after scholar solutions which became type safe it was founded i think became type safe it was founded i think it was only then that scala actually it was only then that scala actually became a positive became a positive rather than rather than a big red flag a big risk for anyone a big red flag a big risk for anyone i think it still happens we see echoes i think it still happens we see echoes of this yet still some companies using of this yet still some companies using clojure scala yeah they like to have uh clojure scala yeah they like to have uh java apis and they kind of like to java apis and they kind of like to although they like to have php i mean although they like to have php i mean if if you're judging based on on how if if you're judging based on on how widely it's used widely it's used people yeah people will uh people yeah people will uh people make bad decisions people make bad decisions so basically i'm so basically i'm following the trajectory so you are following the trajectory so you are doing this in industry you have doing this in industry you have occasional meetings with visitors from a occasional meetings with visitors from a pfl right when when do you see the pfl right when when do you see the momentum picking up when do you see this momentum picking up when do you see this really really changing the trajectory well the big changing the trajectory well the big thing was twitter thing was twitter i think in in the last uh 11 years i think in in the last uh 11 years the the single the one single thing the the single the one single thing which has made the biggest difference which has made the biggest difference scala has been the adoption by twitter scala has been the adoption by twitter and their success and their success and and the fact they managed to and and the fact they managed to reduce their downtime reduce their downtime quite significantly quite significantly at the same time as they were expanding at the same time as they were expanding very rapidly very rapidly and that was about and that was about 2008 2009 2008 2009 and you were in 2008 2009 2008 2009 and you were in europe europe i mean i was in europe so how did you i mean i was in europe so how did you see i mean we live in the bubble world see i mean we live in the bubble world here right like we kind of know well i here right like we kind of know well i was in a bubble within europe called was in a bubble within europe called britain that's right but the the the britain that's right but the the the ripples from here are spreading slowly ripples from here are spreading slowly sometimes the rich midwest sometimes the rich midwest in a few years right in the east coast in a few years right in the east coast and so i was i was really i was really and so i was i was really i was really pleased to see joe barnes from alabama pleased to see joe barnes from alabama so scala has reached alabama that's so scala has reached alabama that's right and it's been there for a long right and it's been there for a long time yeah time yeah but uh so i'm curious how the twitter uh but uh so i'm curious how the twitter uh phenomenon uh reached uk and like how phenomenon uh reached uk and like how did you see this skull explosion did you see this skull explosion affecting it it wasn't it wasn't so much affecting it it wasn't it wasn't so much that the average developer that the average developer even knew that twitter was running scala even knew that twitter was running scala i think it was more a matter of i think it was more a matter of the the tech leaders who whose job it is the the tech leaders who whose job it is to be aware of what's going on in the to be aware of what's going on in the industry industry became aware that twitter had used this became aware that twitter had used this that they'd taken a risk on this this that they'd taken a risk on this this language right and had been successful language right and had been successful with it right and then maybe they should with it right and then maybe they should consider that as well right so it was it consider that as well right so it was it was i mean suddenly not all decision was i mean suddenly not all decision makers were aware of it and certainly makers were aware of it and certainly many many quite reasonably i think still back in quite reasonably i think still back in 2008 saw it as a risk 2008 saw it as a risk but um but um the fact that twitter had been the fact that twitter had been successful uh with scala i think that successful uh with scala i think that that was that was an enabler right and it enabled the the an enabler right and it enabled the the formation of formation of right and you know it was called skull right and you know it was called skull solutions it was cool solutions i i did solutions it was cool solutions i i did a couple of weeks of work uh for them i a couple of weeks of work uh for them i i i did some consultancy back when they i i did some consultancy back when they were setting up i'm so glad they called were setting up i'm so glad they called it type safe the skull solution sounds it type safe the skull solution sounds like uh well there was it was it was like uh well there was it was it was actually type safe was formed from two actually type safe was formed from two companies the scala solutions companies the scala solutions and scalable solutions which was jonas and scalable solutions which was jonas bonaire's company bonaire's company and uh you'd have thought you could find and uh you'd have thought you could find a a sort of a common name between scala sort of a common name between scala solutions and scale right solutions i solutions and scale right solutions i think it's subsumption but yes think it's subsumption but yes but they went with types i think i think but they went with types i think i think for the best yes absolutely that was a for the best yes absolutely that was a great name so and did you stay with great name so and did you stay with scala all that time scala all that time yeah so i haven't written any java code yeah so i haven't written any java code since about 2004 maybe 2005 i wrote some since about 2004 maybe 2005 i wrote some mm-hmm mm-hmm so so were you ever tempted or kind of were you ever tempted or kind of uh uh thinking over whether you should do thinking over whether you should do something else something else i i it's probably best described as blissful it's probably best described as blissful ignorance ignorance i i've i i've i'm aware there's a language called i'm aware there's a language called haskell yes another one called idris yes haskell yes another one called idris yes they sound interesting they sound interesting but the the the free time i have doesn't but the the the free time i have doesn't really allow and i think they're both really allow and i think they're both made in the uk now made in the uk now uh yes yeah yeah uh yes yeah yeah so they're local they they are local so they're local they they are local yeah i'm well i'm actually living in uh yeah i'm well i'm actually living in uh in cambridge in england at the moment in cambridge in england at the moment which is uh where there's a lot of a lot which is uh where there's a lot of a lot of research into right the microsoft of research into right the microsoft research microsoft research yes research microsoft research yes also f sharp is quite big there but as also f sharp is quite big there but as we know from scholar days you know scala we know from scholar days you know scala is a gateway drug to hospital and husker is a gateway drug to hospital and husker later is is the future as we've seen yes later is is the future as we've seen yes i'm looking forward to that i'm looking forward to that so uh so uh so this is very interesting so uh so uh so this is very interesting so uh i mean can you tell us a little so uh i mean can you tell us a little bit about uh kind of uh running business bit about uh kind of uh running business with scala for all this year so with scala for all this year so obviously especially through early days obviously especially through early days right it's it's it's a non-trivial uh right it's it's it's a non-trivial uh proposition to proposition to to work in the industry in this new to work in the industry in this new language and and probably the the nature language and and probably the the nature of the business evolved can you talk a of the business evolved can you talk a little bit about the the the early dates little bit about the the the early dates i i um i i um we weren't successful we uh we we wrote we weren't successful we uh we we wrote a lot of scala code a lot of scala code we we were we we were i mean one thing that did draw us to i mean one thing that did draw us to scala was the fact that we could use scala was the fact that we could use java libraries from scala right java libraries from scala right and it was very convenient being able to and it was very convenient being able to take existing like uh apis and libraries take existing like uh apis and libraries off the shelf and use them within scala off the shelf and use them within scala but i did find a huge amount of my time but i did find a huge amount of my time was spent was spent writing wrappers around those libraries writing wrappers around those libraries and i guess you could even say that and i guess you could even say that that's the that's the uh uh the sort of inkling of where rapture the sort of inkling of where rapture came from it's it's certainly it certainly taught it's it's certainly it certainly taught me me a bad lesson i would say a bad lesson i would say that uh that uh that you should reinvent everything that you should reinvent everything and i and i because because scala didn't have because because scala didn't have anything back then there were no scholar anything back then there were no scholar libraries libraries it was always very tempting just to it was always very tempting just to rebuild stuff reinvent the wheel over rebuild stuff reinvent the wheel over and over again but make it better yes and over again but make it better yes and and i'm not advocating this as a solution to i'm not advocating this as a solution to anything it's anything it's i still find it harder today to to pick i still find it harder today to to pick up somebody else's library rather than up somebody else's library rather than just create my own interesting and uh i just create my own interesting and uh i mean yeah i mean it's a it's a it's a mean yeah i mean it's a it's a it's a flaw that's developed from having worked flaw that's developed from having worked with the language from the right i think with the language from the right i think i see now because every programmer has i see now because every programmer has this little set of code they this little set of code they drag along with them all the time right drag along with them all the time right they develop their own methods and their they develop their own methods and their own utilities so i think it sounds like own utilities so i think it sounds like rapture is your bag of tools which you rapture is your bag of tools which you have taken with you along different have taken with you along different projects so i i can trace projects so i i can trace i can trace code in rapture i can trace code in rapture maybe one or two methods back to 2005. maybe one or two methods back to 2005. uh jamie webb wrote uh jamie webb wrote wrote those methods wrote those methods um the ones i'm thinking of um the ones i'm thinking of stream stream uh data uh data synchronously from one synchronously from one from an input stream to an output stream from an input stream to an output stream or equivalent or equivalent that that is the code that's lasted that that is the code that's lasted with a few with a few a few updates it's lasted over 10 years a few updates it's lasted over 10 years well no uh about 10 years i would say well no uh about 10 years i would say what uh source control system did you what uh source control system did you use oh we we used use oh we we used from the very beginning we used darks from the very beginning we used darks okay okay yeah it's a great it's a great system yeah it's a great it's a great system with a theory of patches the theory of with a theory of patches the theory of patches which uh patches which uh didn't work for uh for the first couple didn't work for uh for the first couple of versions of darks mm-hmm of versions of darks mm-hmm at least i i was i was never sure at least i i was i was never sure whether the theory of patches was wrong whether the theory of patches was wrong or whether my my mental model of theory or whether my my mental model of theory of patches was wrong but we persevered of patches was wrong but we persevered we had occasions where where darks would we had occasions where where darks would get tied in knots and it would be just get tied in knots and it would be just left spinning for ages and ages and and left spinning for ages and ages and and might ultimately complete the operation might ultimately complete the operation we asked it to do and we might get our we asked it to do and we might get our code back so you could you could haskell code back so you could you could haskell code code lovingly nurture this budding scholar lovingly nurture this budding scholar yes source yes yes source yes have you ever been tempted to look at have you ever been tempted to look at this haskell source of darks when it was this haskell source of darks when it was buggy no buggy no i mean i don't i don't read haskell yeah i mean i don't i don't read haskell yeah did you build it from source did you build it from source um um we we would have done i'll tell you why we we would have done i'll tell you why because i've been using gen 2 linux for because i've been using gen 2 linux for the last 10 years so yeah the last 10 years so yeah so i mean i didn't i didn't type the so i mean i didn't i didn't type the commands except the the standard commands except the the standard installation right on gen 2 but installation right on gen 2 but yeah it was built from source yeah it was built from source interesting interesting interesting interesting you still have this dark repository you still have this dark repository i i probably have them somewhere yeah i i probably have them somewhere yeah you should you should contribute to the you should you should contribute to the computer science museum right because computer science museum right because this is this is one of the longest this is this is one of the longest existing repositories in scala you existing repositories in scala you should make sure that it's preserved at should make sure that it's preserved at least you know she's all important to least you know she's all important to github right and then it will be a github right and then it will be a matter of public record forever yeah and matter of public record forever yeah and you know future you know future i continue with darks until um i continue with darks until um probably about 2011. probably about 2011. i use it around the same time right so i i use it around the same time right so i think the scent of git kind of switched think the scent of git kind of switched everybody to git everybody to git yes yeah um dark starch 2.0 was a big yes yeah um dark starch 2.0 was a big improvement that that made it usable improvement that that made it usable really yeah well we have some of the really yeah well we have some of the sage issues and yeah but we were early sage issues and yeah but we were early adopters with with darks again adopters with with darks again and darks didn't go anywhere really and darks didn't go anywhere really right scarlett right scarlett right that's right right that's right some that's right that's right some that's right that's right uh so can you kind of highlight you know uh so can you kind of highlight you know some kind of the most interesting things some kind of the most interesting things you've done with scholar during you've done with scholar during these years these years right okay the most interesting things right okay the most interesting things i've done um i've done um well my talk at scholar days i thought well my talk at scholar days i thought was very interesting i was quite excited was very interesting i was quite excited by that by that so i'm i've found a way to so i'm i've found a way to to provide to provide checked exceptions in scala checked exceptions in scala i probably don't have long enough to i probably don't have long enough to talk about the details but java's java's had checked exceptions for java's java's had checked exceptions for ages and and it always seemed to me like ages and and it always seemed to me like this was a point where where java had this was a point where where java had better safety better safety i mean at a cost of like horrible i mean at a cost of like horrible boilerplate code and and busy work boilerplate code and and busy work uh uh coercing your your your exceptions into coercing your your your exceptions into the right mold but the right mold but it did have this additional safety it did have this additional safety checking that scarlet never had checking that scarlet never had and the reason scarlet never had it was and the reason scarlet never had it was that it you needed to be able to accurately you needed to be able to accurately track the exceptions that could be track the exceptions that could be thrown so if you thrown so if you if you map across if you map across uh uh if you map a lambda across a collection if you map a lambda across a collection say say that lambda that lambda may throw may throw some it might throw i don't know uh some it might throw i don't know uh what's an exception some some exception what's an exception some some exception exception exception but uh the but uh the the map method you can't write the the map method you can't write the signature in such a way that signature in such a way that you can derive the you can derive the uh the exception type right dependent on uh the exception type right dependent on the lambda that's not possible in the lambda that's not possible in in java but i've found a way of doing it in java but i've found a way of doing it in in scala in in scala which is which is involves mixing together involves mixing together like three or four quite advanced like three or four quite advanced features but uh features but uh i've got working prototypes so i'm i've got working prototypes so i'm confident that i'll get something confident that i'll get something working interesting interesting yeah uh working interesting interesting yeah uh i think it will be really interesting uh i think it will be really interesting uh uh to look at that it i i would uh to look at that it i i would yeah i would hope that within a month or yeah i would hope that within a month or so i'll have something that people can so i'll have something that people can actually use actually use um so you so you you give a rapture talk um so you so you you give a rapture talk at um scalability conference at um scalability conference last year which was inaugural scholar by last year which was inaugural scholar by the bay and i think it was a great the bay and i think it was a great success because it was one-liners each success because it was one-liners each of them kind of self-contained showing of them kind of self-contained showing some of the uh beautiful syntax and ease some of the uh beautiful syntax and ease of use of use and i hope we get to do something today and i hope we get to do something today alongside you know following you in the alongside you know following you in the rebel uh but uh i wonder uh how do you rebel uh but uh i wonder uh how do you came up with this idea and how do you came up with this idea and how do you see people see people reacting to that and how much adoption reacting to that and how much adoption do you see happening around the world do you see happening around the world when you present this uh this library so when you present this uh this library so so people people do seem to like the so people people do seem to like the one-liners talk because i've got one-liners talk because i've got about 50 slides each one has one line or about 50 slides each one has one line or maybe maybe two lines of code maybe maybe two lines of code and and because i've designed rapture because i've designed rapture to be as intuitive as possible you can to be as intuitive as possible you can just read that line and know what it just read that line and know what it does and and i've managed to do it in most cases i've managed to do it in most cases whilst remaining completely type safe whilst remaining completely type safe taking advantage of taking advantage of quite advanced features of quite advanced features of scala at least at the library level scala at least at the library level whilst not requiring that the people whilst not requiring that the people using the library need to understand using the library need to understand them them so so for example going back to my for example going back to my my talk at my talk at scala days yesterday scala days yesterday was it yesterday yeah it was yesterday was it yesterday yeah it was yesterday it seemed seems so yeah seems so long it seemed seems so yeah seems so long ago so much has happened since ago so much has happened since uh uh i i introduced the concept of modes i i introduced the concept of modes now modes allow you to pick and choose now modes allow you to pick and choose how you want your exceptions to be how you want your exceptions to be handled so do you want do you want to handled so do you want do you want to return an option do you want to return a return an option do you want to return a try try are you happy with just an exception are you happy with just an exception being thrown maybe you want to being thrown maybe you want to return a future and execute the code on return a future and execute the code on the on on a fork join pool the on on a fork join pool these are all possibilities with mode these are all possibilities with mode and you just import the appropriate mode and you just import the appropriate mode and methods that have been written in and methods that have been written in the in the right way the in the right way which is basically anything in in which is basically anything in in rapture rapture will actually change their return type will actually change their return type based on the fact the import is there based on the fact the import is there so this this is a really complicated so this this is a really complicated thing or you need to understand a few thing or you need to understand a few complicated things to implement it complicated things to implement it the implementation is simple but the the the implementation is simple but the the concepts are concepts are i'd say quite advanced i'd say quite advanced but users end users don't see any of but users end users don't see any of that it's a lot of i think it's a common that it's a lot of i think it's a common feature on skull right there it's it's a feature on skull right there it's it's a couple seconds it's a common feature couple seconds it's a common feature simple once you understand what you're simple once you understand what you're doing yeah and occasionally occasionally doing yeah and occasionally occasionally it leaks occasionally that abstraction it leaks occasionally that abstraction leaks leaks uh but with modes it's been it's been uh but with modes it's been it's been holding up pretty well and you don't see holding up pretty well and you don't see any of the underlying high kind of types any of the underlying high kind of types or or um um implicits or dependent method types implicits or dependent method types which are involved in the implementation which are involved in the implementation all you see is well my my method return all you see is well my my method return type has magically changed type has magically changed and and and and it was easy it was easy and not just this so i think this is a and not just this so i think this is a theme on rapture right like by varying theme on rapture right like by varying the imports you can make the imports you can make very different behaviors and i think very different behaviors and i think this as i'm not just a or when you this as i'm not just a or when you mentioned this yes right and i think mentioned this yes right and i think this is very interesting so uh uh i this is very interesting so uh uh i wonder actually that that sounds like a wonder actually that that sounds like a very good modular way to alter the very good modular way to alter the behavior behavior uh so can it be for instance uh so can it be for instance combined with the build system combined with the build system to produce different behaviors in to produce different behaviors in different contexts right you can have different contexts right you can have something on staging something in something on staging something in production by varying the imports production by varying the imports you will change the behavior of the you will change the behavior of the library and the the underlying call so library and the the underlying call so you'd have to well you you'd make one you'd have to well you you'd make one change to the code work yeah definitely change to the code work yeah definitely yeah yeah so you can have method return types that so you can have method return types that are dependent on the import are dependent on the import that's how modes work yep that's how modes work yep um um and and yeah you can do different completely yeah you can do different completely different things run different code different things run different code dependent on import that that's that's dependent on import that that's that's certainly something you could do certainly something you could do whether you want to have that whether you want to have that configuration as part of the source configuration as part of the source or as a compiler flag or as a compiler flag or as or as an environmental an environmental variable or something i wouldn't variable or something i wouldn't recommend environment variables i i try recommend environment variables i i try to make the source code usually to make the source code usually a specification for how the software a specification for how the software will run that that's right that's will run that that's right that's i think generally preferably right so i think generally preferably right so you can drop but you're dropping this you can drop but you're dropping this symbol so you can use files symbol so you can use files right but i mean there are issues with right but i mean there are issues with that for example you can't change that that for example you can't change that behavior at runtime then so so right behavior at runtime then so so right there are different approaches but i'm there are different approaches but i'm thinking about things like you know thinking about things like you know typical use of a cake pattern would be typical use of a cake pattern would be to replace a relish base with a mock to replace a relish base with a mock right so right so it sounds like you can achieve a lot of it sounds like you can achieve a lot of similar things with rupture by changing similar things with rupture by changing the boards yeah the imports do give you the boards yeah the imports do give you a lot of flexibility and i've i've gone a lot of flexibility and i've i've gone through using the cake pattern um i i through using the cake pattern um i i used that for years and years used that for years and years i i was reasonably successful with it i i i was reasonably successful with it i think think uh i mean i came up with a name uh i mean i came up with a name i i i decided one day that it was uh i i i decided one day that it was uh well i i'd actually uh uh eaten the cake well i i'd actually uh uh eaten the cake that day oh on the mailing list on the mailing list uh uh which which i answered which to which my which which i answered which to which my answer was answer was where you need to use this where you need to use this pattern here and it didn't have a name pattern here and it didn't have a name and i thought can we can we like find a and i thought can we can we like find a better way of describing this better way of describing this and and one of my colleagues had his birthday one of my colleagues had his birthday that day and uh we'd had a cake for him that day and uh we'd had a cake for him so i sort of the cake was there on so i sort of the cake was there on on the table i thought on the table i thought well it's kind of well it's kind of you you're slicing every trait is a you you're slicing every trait is a slice of that cake and then you've got slice of that cake and then you've got layers within the cake which sort of layers within the cake which sort of represents stacked or nested yes traits represents stacked or nested yes traits and and the the compiler neatly checks all these the the compiler neatly checks all these slices fit together perfectly and uh it slices fit together perfectly and uh it seemed to fit people liked it and uh seemed to fit people liked it and uh that's a great name it has a lot of that's a great name it has a lot of illusions right let them eat cake illusions right let them eat cake to have the cake and eat it too well to have the cake and eat it too well yeah i'm not sure you can have your cake yeah i'm not sure you can have your cake but you can but you can it does introduce uh many problems if it does introduce uh many problems if you're not getting and there are of you're not getting and there are of course a lot of uh deep discussions course a lot of uh deep discussions right i think it's a very common thread right i think it's a very common thread in the in the scholar forums you know are what are the scholar forums you know are what are the you know how the cake pattern works you you know how the cake pattern works you know what are the benefits should we use know what are the benefits should we use cake powder and there is sometimes there cake powder and there is sometimes there are revolutions against the cake pattern are revolutions against the cake pattern right right yeah i i would say if you yeah i i would say if you if you set out with if you set out with the cake pattern in mind as your as your the cake pattern in mind as your as your goal goal you'll probably approach the problem the you'll probably approach the problem the wrong way wrong way i think if you find if you find you've i think if you find if you find you've written some code that ends up looking written some code that ends up looking cake-like cake-like maybe that's maybe that's maybe that's legitimate but uh i don't know i've i've gone off the cake i don't know i've i've gone off the cake pattern a little bit not as much as most pattern a little bit not as much as most people i think people i think i think daniel spiwak still still i think daniel spiwak still still believes it's a it's a good thing believes it's a it's a good thing but we're sort of the last but we're sort of the last uh the last couple of people who are uh the last couple of people who are still still sort of using it sort of using it so what do you use nowadays when instead so what do you use nowadays when instead of the cake part um of the cake part um type classes type classes uh uh i think i think i mean i mean to say that type classes i mean i mean to say that type classes are a drop in replacement for for cake are a drop in replacement for for cake is is is is maybe misleading but maybe misleading but normally if i need normally if i need uh uh normally if i need to normally if i need to to do something that that's not to do something that that's not sort of sort of obvious in in in sort of the the java obvious in in in sort of the the java subset of syntax that scala has subset of syntax that scala has i i would reach for implicits and type i i would reach for implicits and type classes classes okay okay so i think there is an endless amount of so i think there is an endless amount of things we could discuss right and things we could discuss right and probably i'll definitely follow we'll probably i'll definitely follow we'll follow up next time we'll have you follow up next time we'll have you but you know i will probably close with but you know i will probably close with your your uh given you know uh given you know like uh like uh one of the one of the person's most experienced right and i person's most experienced right and i will compare it with the first 10 you will compare it with the first 10 you know first 50 years of computing when know first 50 years of computing when acm celebrated the first 50 years of acm celebrated the first 50 years of computing computing and i was uh and i was uh at penn at the time where antioch was at penn at the time where antioch was built so this was on the celebration built so this was on the celebration sites they made it a hundred years of sites they made it a hundred years of capital celebration because they capital celebration because they celebrated the next 50 years and the celebrated the next 50 years and the first right so so you've seen first first right so so you've seen first initial scala uh we're gonna probably initial scala uh we're gonna probably meet here again and talk uh about meet here again and talk uh about 20 years of scholarship in 2024 2025. 20 years of scholarship in 2024 2025. that's right that's right so what do you that's right that's right so what do you want this next 10 years to be what want this next 10 years to be what do you think they're going to be do you think they're going to be uh where would you like it to go oh more uh where would you like it to go oh more of the same more of the same more yeah that's great that's it sounds great yeah that's great that's it sounds great to me all right here's tomorrow the same to me all right here's tomorrow the same thank you thank you you