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From YouTube: Keynote: Hedy: Creating a Gradual Programming Language - Dr. Felienne Hermans

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Keynote: Hedy: Creating a Gradual Programming Language - Dr. Felienne Hermans, Leiden Institute of Advanced Computer Science

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Good morning, everyone- yes, I'm here to talk about hedy, a gradual programming language for programming education that I made, but before we really go into the details of hedy, I want to take you through sort of the history of hadi and my history in teaching programming to children. So in the year 2013 that's getting increasingly longer ago, as I gave talks about this, I started to teach programming to kids. So there was a group of kids in a community center in rotterdam in the netherlands where I lived and they needed a programming teacher.

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So I thought these are little children. These were 10 11 12 year olds. This will be fine. I have a phd in programming writing in software engineering. How hard can it be? How difficult questions can they ask me this? This would be totally fine. I thought it was actually a lot harder than I thought and one of the things that made it really hard. Is that subconsciously when I started to teach programming to those children? I thought back at how I learned programming when I was a kid.

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So this is me this is me behind my dad's big computer, when I was about 10 years old learning to program, and how did I learn to program, certainly not from another human? There was no programming teacher, no, no adults, my parents or friends of my parents. No one knew programming.

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There were no adults to really teach me programming, so I never really went through a programming lesson. I didn't really have an idea of what a programming lesson looked like what I did have was this book. So this is a book from which you could learn programming at the time and it's like I'm, I'm very old. So this is before the internet right. Well, the internet existed, but I didn't have it in my house.

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So I had this book and this book was supposedly going to teach me how to program, but it wasn't a book that said: oh do this, you know this is a variable. This is a loop if you would open this book. This is what would be inside let's.

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This is printed out, programming list right, and this is so all that it didn't come with a floppy or cd or anything you just had to manually type those codes into the computer to get it to work and, as you might hear from my english, english isn't my native language, and at this time I didn't really know any english. So none of the words really made sense to me. I just copied everything into the computer sort of until it worked right, so so that was really hard, and this is not just my experience.

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This is an experience, many people, the children of the 80s share. I saw some people ignoring in the audience. Many of us grew up this way by learning from books and just hitting the keyboard until it worked, and that creates a certain culture of thinking about programming. Basically, we've all been sort of stockholm syndromes into thinking that compilers are lovely teachers right yes, this is this is fun.

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This is a good way to learn, is just try things and the compiler will tell me if there's an issue with that in mind, I was teaching children in the year 2013 programming, so the children were very excited to learn programming right. They were coming voluntarily to the community center on saturday saying hey. We really really want to learn this, so I thought okay, this will be fine. I'll just show them python. Right. Python is known for its easy to learn syntax. This will be totally fine here, children. This is python, it's very exciting.

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What we're going to do? We're actually going to print text on a screen super cool, and in order to do that, you have to type print and then brackets and then quotes, and then the text and then what you'll have is text on the screen. So the kids were like okay, okay, okay, probably this is programming. This is fine.

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However, of course it wasn't always the happy pads. Sometimes kids made a mistake. An honest mistake like this one accidentally using a capital p in print. I just this sort of makes sense because you are supposed to start lines sentences with capitals. What does python say? Name print is not defined.

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Okay, so, as an error message is sort of okay, it tells you what's wrong. This is not that hard. It got worse. Now we I forgot a closing bracket. Just all one closing bracket seems like I'm very, very close. I should maybe get 9 out of 10 points for this. No no python says no syntax error, unexpected eof, while parsing right, imagine you teach a bunch of 10 year olds and one raises their hand and says teach your teacher. What is parsing like well, I don't want to talk about that now right.

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I just want to talk about concepts. Here's another one. This is even worse. I think here there's a space in front of the code, so everything is correct, everything's, fine! It is literally exactly the example that I showed them, but there's a space so is python. Happy can python simply just ignore this space like you would expect? No, no, of course, not indentation error, unexpected indent lesson, one teacher: what is an indent like I don't want to talk about that now. This is this is too hard right.

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So over time I saw kids getting more and more frustrated. They were very motivated in the beginning, but after a while they were just like you know. If this is programming, never mind, I don't I don't see how this will be fun. On the other side, some of them, of course, were like okay. I know I want to be a programmer. I can. I can take this pain for a little bit longer, but many of them disengaged by all these small things.

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So I realized. Okay, maybe compilers are not lovely teacher right. Maybe this frame of teaching is just not a right frame. There was really a difference in what I thought was going on and what the children thought was going on. Something like this. This is a simple python program which just lists one two, three four or actually it lists zero. One, two three, but let's say for the sake of argument that this is just one two. Three four, so what I wanted to talk about is repetition. I was like oh children look here.

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This is conceptually the idea of a loop, the idea that a line of code can be used multiple times, but this wasn't what the children were seeing. The children were looking at the codes and were like oh rules brackets colon spaces.

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They couldn't really focus on the concept of programming, the concept of repetition because they were so concerned with all the details, and I learned a lot actually about how people learn and how people process information- and I figured out that this is because programming causes too much cognitive load if your brain has to think really really hard. The technical term for that is cognitive load, and if you want to know more about cognitive loads, I sort of went on a on a rabbit chase and I learned a lot about programming and cognition.

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So much that I wrote a book about it. So if you want to also learn more about this and there's a link at the end of the talk, so I wrote a book called the programmer's brain about how cognitive loads and other cognitive concepts actually impact your programming.

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So I got so interested because I thought well we as humanity, you know we succeed in teaching children math all children, we succeed in teaching children, language, all children, not just the one that are ones that are really motivated. So it's like okay, how do other fields manage cognitive loads? How do we do this, and one of the things that was so interesting looking into language education is that in learning to write there are so many different ways to get it correctly right?

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If you have a five or six year old- and they write like this- you will not say syntax error floating a right, you'll see if this is a five or six year old, you're like well done buddy. This is perfect, those are letters and not random scribbles. This is not wrong. This is not almost correct. This is just right. This is at their level the correct way of doing stuff.

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Later on, we add concepts, we say: hey, there's more than just letters, there's also words and you can group the letters together and then they form words and then we add slowly different rules. After a while, we say hey, every sentence now starts with a capital letter. Kids are like okay practice practice practice and they know this rule, and then we say every sentence ends in a period. Kids are like okay. Well, that makes sense, and there we're not.

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This is not just syntax right because we're also adding expressiveness to the language, because once we have a period we can make sentences that span multiple lines right, so our language is now more powerful because we have the concept of a period to separate different lines. So I was like: hey rules gradually change. If we teach language, how do we do that in programming education?

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You know, how do we manage cognitive load? Well, not very well. We give kids the full syntax and the full language from the beginning right and even when you say well in the first lesson, we just teach print. We don't talk about code blocks, inevitably because the whole language is there, you might have to talk about it, because if you put a space there python will say indentation right, so you're not chopping off parts of the language.

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You always give kids access to the full language like you would start if you would teach language with the full language with all the bells and whistles initially so then I thought hey.

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Couldn't we teach programming like we teach reading? Couldn't we also make a programming language that gradually changes and, as I said, I was just teaching these kids on a saturday. It wasn't my plan to to do anything research-wise. This is just a hobby, a volunteering gig, but I I did have a phd in in programming language design and I built an ide when I was working on my phd thesis, so I thought well. I have the skills to build something like this, so I started to experiment with something that ultimately became.

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The hattie programming language, that is, a gradual language, so in the first level of hedy, you just type prints and then you type whatever you want and it just prints hello and then gradually we add syntactic elements and with that also concept, so in level four, we introduce quotation marks and later on all the way at the end of the trajectory. Only then do we add brackets because they're not necessary. Initially, if you're, just printing one thing, you don't need brackets right, so we made this language a heady, a gradual language.

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So I'm going to show you a demo with a few screenshots just to give you an idea of what hedy looks like. So this is the heady user interface. It runs entirely in the browser and that's by design, because many schools and programming clubs cannot install software on their machines either because they don't have the skills or more commonly they just don't have the right access levels in computers to install something. So you just go to www.hedicode.com and you can start programming straight away.

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The code goes here on the left side is where you type something like print hello and then print welcome to openjs world, and if you would run that the output appears on the other side, so you see no brackets no quotes nothing. Your kids can just focus on hey. This is programming. These are the ideas in programming. Oh, you put some code here and then output comes on the other side. That's what programming is what's also a really really important part of hedy is that we have built-in lesson plans.

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So everything you need to know is right there in the browser, because one of the things I also found to increase cognitive load is, if you have lesson plans on paper or even in another browser tabs kids have to go from the one thing to the other thing: they read the lesson plan and they have to go to the coding environment and that also creates extra cognitive load. So we put the lesson plans right there, so everything is sort of one in one package.

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What we also have is a cheat sheet. So if you push this button, all commands that are available in a level are shown to you, because sometimes kids, of course, even though we gradually change the concepts, they might still forget, what is there in a level? So we have these cheat sheets.

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What we also have is easy to read error messages. So you see now that I made a little mistake. I removed the I in print.

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Firstly, you see this because the syntax highlighter now no longer makes the keyword purple, but also if you would run the code, it says we can't run your program. Prunes is not a heady level. One command. Did you mean print? This is quite actionable.

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This is stated, we hope in language that kids can understand, and it shows you what to do next and one of the reasons of course I mean I am cheating a little bit, it's easier to generate these very, very meaningful error messages, because the language is so small in level one. We just have five keywords right, so it's relatively easy to guess what kids meant, which I totally understand why python error messages are the way they are because there are so many different things. That could be the mistake. It's harder to guess so.

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A smaller language also allows for better and tailored error messages.

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What we also have level one and that's quite important, is the idea of you, user input and output, so not just printing, but also asking we have a keyword, ask that is going to put an input from there like, like inputs in python. So it says what is your name and then you can type in the little green field and the echo will repeat your answer back to you. So you get this idea of. Oh I'm storing a value somewhere, but you don't need to do anything.

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We just want to imprint upon children ah programming, it's a thing where you have inputs and you have outputs and just for comparison right. If you want to do this in python in your first lesson, have a very easy program that just asks for your name and then says hello name. This is what you have to type right, so just the difference between this- and this is so big for a novice right. Getting this right, making sure that all the brackets and commas and the quotes are there for some kids.

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This is just a hurdle, they will never cross and then they give up because they decide. Programming is too hard.

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This is level two, so in level 2 we introduce the idea of a variable more explicitly more explicitly than in echo. So you can say: name is hedy, h is 15, and then you can just say: print name is 8 years old, and if you run this, it will just output this right. So for us, programmers are like this is weird: how does how does the thing know? What is a variable and what is text right?

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But of course, it's not so hard to do a little bit of static analysis to figure out what's a variable and what is text, because we want kids at this level really to be focused on the concept of a variable and not on all the syntactic fluff that will come later so sort of hedy does the heavy lifting of figuring out what's going on, so that the programming experience is easy and only gradually increases. So I'm not going to take you through all levels.

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We have 18 levels now and at the end of hedy in level, 18 you're doing a syntactically valid subset of python. So we really slowly want to get you to python and then our idea as well, if you're there. You know if you're at python in level, 18, you've seen conditions and while loops and for loops and variables and lists you could sort of from there consume python materials and and enjoy the rest of your programming life in python or in another programming language. But before we are there in level 18.

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Just to give you a sense of what we have in level. Four, we add quotation marks, but then that's the only thing we add, so we really focus the attention of the learner on the idea that there's a difference between variables and plain text strings and you have to tell the computer, which is which, in level seven, we add repetition, but there also we start gradually.

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So the first way of repeating is just saying repeat three times prince just on one line: no blocks yet no four, I in range yet just a simple form of repetition and that's also, we gradually unpack to go towards a for loop.

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So one of the things we're super super excited about is that hadi now as you've seen, it is in english, but we actually support multiple different languages. Right, as I said when I was first learning to program, I didn't know any english, so I saw the kids in my programming club, which are dutch children, also struggle with error messages in english. So you can go to your settings if you have an account which is free by the way, and you can set your preferred ui language and also your preferred keyword language.

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So, just if we set it to spanish, everything will change to spanish, including giving you the option to program with spanish keywords, and we didn't stop at spanish I wanted to, but then people from the community kept pressuring me that I also wanted other languages, including rights to left languages, which I didn't want to implement, because it was a lot of work. But of course, once we did it, it's totally worth it. So we also support right to left languages.

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You see here, programming, arabic, where the whole ui, of course is swapped and also all of the keywords are in arabic. We have farsi as well. This also, as you can imagine, greatly lowers the cognitive load for children. You can imagine well it's hard to imagine for me, but you can. You can sort of imagine that if arabic is your first language and then you have to learn python that that's like right. That's for us even non-english speakers. It's like this and for english speakers.

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Maybe it's like this, but then, if you, if you have to use a different alphabet and certainly the whole ui, everything is not like. You're used to that's a very, very high threshold, so yeah it was a lot of work, but I think it's ultimately worth it that we now also support right to left languages.

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So before you before. I close. I want to give you a sense if you know how stuff is going with hedy, because, as I said, I built this as a small research prototype for a research paper in one christmas break in 2019, I built the first prototype in a few weeks and then it sort of sort of exploded from there, which was nice one of the things a few months ago. That was really nice is that I woke up to this tweet.

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This is guido from rossum he's the creator of python, and he said I just discovered honey, a gradual programming language, a new idea. How did these programming to beginners very cool and that this is really, of course, very, very, very nice to see, especially because github also has once said that you shouldn't teach python to 12 year olds, which I think sort of. I agree with now that now that I've tried, so it's really really cool to see that he thinks also. This is a good way to get kids into python.

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So far, so we launched in early 2020 and over 2 million hadi programs have been created worldwide, out of which 800 000 are unique programs. Of course we have hello everyone in the database many many times, but there are 800 000 different programs that children have created, which is like amazing and and so far we have an error rate of about 25.

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So 25 of our programs that children create on the website have a syntax error and then you might be like hmm 25. That sounds like a lot. However, we know from research that regular programming languages for novices like java or python, have error rates around 50.

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So we are quite happy with 25, even though, of course, we're always keeping an eye on the error rate, and we don't want to have too much errors, because that means that the concept isn't very clear, but generally, we think we do a great job at smoothening the trajectory into full-size programming languages.

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Just so you know, heady is free and also open source we're on github. So if you want to contribute, we have, I think, over 100 open issues. So if you want to help out, that would be very, very nice and you can't just help out with programming, even though we we'd be very grateful for your help. We also like to add more languages. Currently, we support 25 different languages as you've seen english spanish arabic also simplified chinese hungarian.

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Well, I don't even know the list. We have many, but we've of course like to have more and we use a tool called webplate where you can just translate in the browser. Even if you don't know any programming, you don't know any python, that's not an issue! You just go to our website link and you can translate some content there. So if you do want to help out in that way, we'd be really really grateful.

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That's it that's everything I wanted to share. If you want to follow me on twitter, I'm at felina. If you want to know more about my work, then you can go to my website felina.com.

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If you want to read the book, the programmer's brain that dives a lot deeper into all the cognitive aspects of programming and learning to program not just for children, but also for programming professionals, you can go to felina.com book and if you want to know more about hedy, you can go to flinder.com hadi. Thank you very much.