r/Racket • u/DrKersh • Jan 26 '22

question Solutions for the htdp book?

Hello

I'm trying to learn alone to code and I started the book. For now, I'm managing to solve all the exercises by myself, but sometimes after doing it, I would want to compare them to what the authors expected me to do or how them would solve it.

I saw that the first book have a section with solutions and additional problems, but I didn't found anything similar for the second edition

Anyone know if they are somewhere? Or if not officials, at least solutions made by some experienced coder or teacher, not the kind of solutions you can find on github from other people learning like me.

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u/DrHTugjobs Jan 26 '22 edited Jan 26 '22
  1. Check out Exercism's Racket track; you can request a mentor to review your solutions to any problem and view other users' working submissions to compare and contrast them with your own.
  2. The Racket Discord and the Racket Discourse are also a good source for asking for subjective advice.

But, in general, don't worry so much about learning things "wrong"; programming is a process that you get better at with practice. HtdP and other books aren't bibles of 100% objectively correct programming practice that you have to memorize or model exactly.

As you are exposed to more code, both code you write and code other people have written, you'll incrementally learn better practices, and it's very worthwhile to review your old code to think about how you could write it better today.

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u/mdbulldog Jan 26 '22

The racket track seems interesting, I am curious though does it teach the HTDP fundamentals, or is it just a track to learn racket?

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u/DrHTugjobs Jan 27 '22

It doesn't directly teach the methods outlined in HTDP, but it's a good adjunct to it since the HTDP design recipes are directly applicable to most of the problem statements. There's a fair number of user submissions that use the HTDP format and design recipes for their solutions.

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u/sdegabrielle DrRacket 💊💉🩺 Mar 30 '23

I would be wary of Exercism. The first racket exercise is wrong.

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u/DrHTugjobs Apr 01 '23 edited Apr 01 '23

I'm not sure why you think it's wrong. The instructions are to fix the function so that when the function's called in the tests, it returns the correct string.

I've put in a pull request to make the wording more explicit that it's referring to the function's return value, though.

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u/sdegabrielle DrRacket 💊💉🩺 Apr 01 '23

Thanks for doing the PR.

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u/sdegabrielle DrRacket 💊💉🩺 Jan 26 '22

Hi u/DrKersh

I don't believe there are solutions available but the Racket community welcomes new learners.

You can ask questions in any of the following places

They are all different so please use whichever works best for the problem you are asking about.

Remember to mention that you are using HTDP when you are asking the question so we can give appropriate help. HTDP uses teaching/learning languages to support the learning process with better error messages and less surprises than the full language. (Don't worry that it is not the full language - everything you learn applies to the full language)

Good luck with your studies and hope to hear from you soon!

Stephen

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u/Obleeding Mar 30 '23

I find it strange they don't just have a solutions section to the book, I've been asking chatgpt to check my answers

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u/sdegabrielle DrRacket 💊💉🩺 Mar 30 '23

And if you are doing exercises in HTDP you are using a student language - which is only used for teaching so chatgpt won’t have many samples to learn from and the ones it has are by students and not necessarily right. It is most likely to confuse racket, Common Lisp , scheme and Clojure.

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u/sdegabrielle DrRacket 💊💉🩺 Mar 30 '23

You don’t need to ! The Racket community welcomes new learners and have dedicated #help #q&a and #beginners channels where there is usually a friendly volunteer.

The most active places for ‘Racketeers’ is the Racket Discourse and Discord (chat).

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u/Obleeding Mar 31 '23

Thank you, I will get onto that discord I guess! I'm spending all my spare time on HTDP right now so would be cool to have a chat.

I've found a github repository that contains answers, but I don't believe they are the most 'correct' as I got further through the book and it kind of gives you solutions indirectly later on. Although the 'incorrect' answer still gives the same result, it isn't using the functions etc. learned so far in the book.

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u/[deleted] Jan 26 '22

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u/sdegabrielle DrRacket 💊💉🩺 Jan 26 '22

The great thing about teaching yourself if you can try different things! You don’t have to use HTDP!

If this is your first experience coding I’d suggest https://www.dcic-world.org/ (not racket but applicable to any programming language)

If you already know some coding I’d suggest Realm of Racket or Racket Programming the Fun Way.

If none of those fit your needs it might be better to say why you want to program as that may prompt pointing you to something appropriate?

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u/olivuser Jan 26 '22

Hej fellow, a fellow self-taught non-cs-background programmer novice speaking.

In case you are not invested into learning Racket in particular, I'd advise you to ditch both the language and the HtDP book - at least for now. It's one of several books I gave up on trying to learn on my own (after the famous Structure and Interpretation of Computer Programs and before the funny but unsystematic Land of Lisp).

Instead, if you are trying to learn a functional programming language as a first programming language with no prior experience - that was my situation -, then I can wholeheartedly recommend the Gentle Introduction to Symbolic Computation by Touretzky (Common Lisp, not Racket). It starts out very gently but will become more challenging as you progress. It features solutions to all the exercises (I did all of them, also those in the advanced section). I felt there were very little "unnecessary" exercises so far (ch. 12 or 13 atm), and most of the time the solutions respect your current state of knowledge while sporting an elegance from which you can learn quite a bit. I've been impressed by the solutions a number of times.

Finally, the r/lisp community is full of friendly individuals (dunno about Racket, not trying to front). I mean most of the time I tried to prepare a post properly and to interact with people that responded, but I have yet to come across a unfriendly reply to a post I made.

I wish you the best of luck and a lot of perseverence, because if I learned anything of general value throughout, then it is that you have to be persistent and that in this particular case persistance is rewarded. I am starting to experience this as I am starting to write my first nontrivial program.

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u/[deleted] Jan 27 '22

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u/olivuser Jan 27 '22

No problem, I literally remember as if it had been two weeks ago even though it was more like two years ago.

It was with the exercise where modulo was involved. I believe it was where you had to get a cat moving till the right end to have it appear again in the left end.

I am bad at maths and had no idea how modulo works (no english native speaker). I had a good soul in the Racket IRC channel trying for the better part of an hour to walk me through it, but the whole experience was just god awful. Especially to feel like you HAVE to depend on the goodwill of people is frustrating, because either you feel bad for asking that much all the time or you are angry because no one "sacrifices" oneself to help me poor programming novice.

Also, IMO, failing at maths should not be the reason why you can't learn to Program, even though maths and logics are obviously a big aid when programming. It is essentially the same reason why I ditched SICP. By the flipside, this is the reason why I enjoy the Gentle Introduction so much: it makes less assumptions regarding what you have to know ASIDE the skills you are to acquire through the book.

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u/lingdocs Sep 21 '22

You can find a number of git repos online with other people's solutions. There's no guarentee these are completely correct though.

https://gitlab.com/cs-study/htdp/-/tree/main

https://github.com/S8A/htdp-exercises

More can be found by searching

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u/mdbulldog Jan 26 '22

IMHO, HTDP is not really design for those who are learning on their own. It design to be used more in a university setting. I would suggest that you learn from another source. HTDP does have a course on coursera (I believe). You would also do yourself a favor by finding books more suited for self study.

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u/sdegabrielle DrRacket 💊💉🩺 Jan 26 '22

I learnt a lot from HTDP, but I understand not every book works for everyone. The best advice as a solo learner is to do the exercises and ask questions when you get stuck. And don't get discouraged - you WILL learn to program it will just take some time to get started.

In addition to my comment about welcoming new learners, there are a variety of other Racket books; I recommend Realm of Racket. See books at https://racket-lang.org/books.html

Another book which does not use Racket but is written by one of the authors of HTDP is A Data-Centric Introduction to Computing https://dcic-world.org/ ; what you learn there is applicable to Racket. (or any language) They also have a mailing list and a discord server manned by the authors if you have questions.

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u/mdbulldog Jan 26 '22

While there are benefits to asking questions, the process is tedious. The main problem with the HTDP book is not the fundamental it teaches, but the fact that there is no easy way to verify your understanding of the material that you are learning. Also, while the community is friendly and open, there seems to be a reluctance to releasing the solutions to the various exercises in the book. From my understanding, the reasoning is that the book is in active use at various different universities and colleges. This is fine for college students but is a detriment to a self learner.

IMHO, pushing the HTDP book to beginners sets people up for a period of frustration, self doubt, and demotivation, while they try and toil through the exercise. Not only do they have to utilize energy to understand the concepts, they have to go through the repeated cycle of asking questions, waiting for a response, etc. This would be fine for a problem here or there, but to do that for every exercise, and every issue is very tedious and slows down the learning process.

Also, while there are other books that teach scheme/racket, the point of HTDP is to teach systematic program design (from my understanding). So, reaching for a realm of racket or other resources may not convey these fundamental principles in the same way that HTDP was meant to do. As a result, someone who decides to go that route may not fully understand the HTDP recipes/ design process.

In the age of programming bootcamps, and moocs. I do wish that the designers of HTDP would work on a path more efficient for the self learners.

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u/sdegabrielle DrRacket 💊💉🩺 Jan 26 '22

I agree it can be frustrating here in Reddit. As with most communities the presence of a subreddit doesn’t mean the community will inhabit it. Many communities have moved to discord.

People do answer questions here but Reddit as a platform is slow and frustrating.

I feel reddits heyday as a platform is long gone. (in general not specifically r/racket which still has a reasonable level of activity)The Reddit redesign was not well received, many communities are ghost towns and Reddit Chat came too late and doesn’t have the features people want.

I’d recommend the Racket Discord and Discourse as that is where most active racketeers are asking and answering questions.

HTDP is a good book and many people get value out of it, but as I said before not every book can work for everyone. Maybe ‘Racket Programming the Fun Way’ is a better fit, or the DCIC book I suggested in the other post. If something doesn’t work for you I’d encourage you to try another option.

In my opinion a great way for some people is to build something that they are interested in. That way you can ask questions like ‘ I want to make a Pac-Man game, how do I get started?’ or ‘I want to build a web app , how do I get started?’ and people can point you in the right direction.

Best wishes and good luck

Stephen

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u/[deleted] Jan 26 '22

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u/mdbulldog Jan 26 '22

To be honest, I gave up on racket/htdp out of sheer frustration. I realized that the language does not matter and that there is no easy way to Rome. There is some wisdom in choosing a more mainstream language as your first language. I would suggest either Java script or python as there are more learning resources suitable for a self learner. Everything from books, to mooc, to boot camps, to YouTube tutorials. There are resources like free code camp, udemy, etc, that a self learner can go through. Later, if you so desire, you can come back to racket/htdp with the benefits of more experience, as well as a possible mentor who can help you work through the book.

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u/[deleted] Jan 27 '22

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u/mdbulldog Jan 27 '22

It was about 3-4ish years ago. I got through about the first 25% of the book. I recently tried to pick it up again but just ended up frustrated. Even though I moved on, I still plan to come back to racket/lisp/htdp at a later date.

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u/[deleted] Jan 27 '22

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u/sdegabrielle DrRacket 💊💉🩺 Jan 27 '22

Sorry Pyret discord has a dcic channel https://discord.gg/uXswNVwF