Zed finishes Learn Python The Hard Way

http://sheddingbikes.com/posts/1285754959.html

by RyanMcGreal • 16 years ago

206 111 16 years ago

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geoscopic2• 16 years ago

Cool. Why isn't it 1.0?

jcdreads• 16 years ago

Because he "…will now be editing it and doing the index," presumably.

geoscopic2• 16 years ago

Good point. Thank you.

shin_lao2• 16 years ago

Unless I'm mistaken there's no chapter about functional programming in Python (lambda functions, filter(), map() and reduce()).

I really think it's acceptable to introduce these function to newbies, I'll go as far as saying it's actually a good thing.

I like the chapter on automated testing.

charlief2• 16 years ago

While I do agree those principles are useful, I think introducing those topics would diverge the focus of the book. I think the goal was of introductory nature not comprehensiveness.

microtonal2• 16 years ago

There are some great beginner's books out there that barely cover functional constructs (e.g. PragProg's 'Learn to Program'). But I have always felt that such an omission is really a bad mistake. map/fold/filter introduce two very important ideas:

- Higher-order functions

- Many tasks are just list transformations

What makes things more painful is that Java is so omnipresent in CS education. Since Java only contains such concepts implicitly (and require a lot of verbosity), I haven't encountered many (if any) Java books that go into functional concepts.

It's like learning UNIX without covering pipes. Sure, you can work with UNIX, inadvertently emulate it using redirections from and to files. But it will never be as effective.

steveklabnik5• 16 years ago

The Python community has frowned on functional programming, reduce isn't in basic Python anymore, and they almost took out lambda: http://www.artima.com/weblogs/viewpost.jsp?thread=98196

RyanMcGreal4• 16 years ago

Strange that they took out reduce() but not map() and filter(), which you can easily replicate with list comprehensions.

ubernostrum• 16 years ago

reduce isn't in basic Python anymore

It's in a module in the standard library, a module which contains a bunch of tools for working with higher-order functions. Or, in other words, if you've got a Python 3.x installed, you've got a reduce function available. The only difference is that it's no longer in the default global namespace (map and filter still are, of course).

This matches up pretty cleanly with my actual experience of writing Python; I've written a hell of a lot of Python code these past 6-7 years and so far as I can recall I've never used reduce.

(and if you want to get picky about this, keep in mind how much of Haskell requires import statements to get at -- moving less-commonly-used stuff into standard modules is not a bad thing at all)

tdavis• 16 years ago

Ditto for generators. In the process you could introduce pipelining and thus give a window into the Unix way which is probably pretty relevant for a newcomer. Or I've just been around too long to know what's relevant for a newcomer.

jokull• 16 years ago

Yeah generators are awesome. +1 for a chapter on them with small sprinkles of functional programming.

jerf2• 16 years ago

He didn't cover defining first-class functions that I could see in a quick check, didn't cover generators, and I think most disappointingly, didn't cover __metaclass__. That's some critical stuff for Python programming right there, everybody needs __metaclass__.

Ahem.

You have to pick what to cover. For a beginning Python book, I'm underwhelmed by the need to drag an entirely new and foreign(-to-Python) paradigm into the beginning Python. I say this as someone who does a lot of functional programming, someone who is using a lot of lambda, filter, map, and reduce is someone who is stubbornly refusing to program with the native idioms, which are named functions (defined inline is fine), list comprehension or loop, list comprehension or loop, and loop respectively. It is not that enormous a gain, and will lose from Python fighting you all the way. (Plus you'll probably miss some opportunities to use generators, overload the special methods, and the other things you can do with native idioms, if you're trying to program Haskell in Python.)

sharms• 16 years ago

I have programmed literally hundreds of thousands of lines of python without using classes or __metaclass__, as a counter example.

When dealing in industry, we can't always hire the best talent, so there is no need to make things overly complex. Simple solutions work best for a lot of scenarios, and I haven't been limited by it yet.

Not to bash Perl, but the whole reason we write in Python is because there were too many people on our team writing in Perl using too many obscure constructs that took too long to review / revise (especially years later when team members changed and code was forgotten in parts)

yummyfajitas• 16 years ago

As far as I know, this piece of code (containing a lambda, map and filter) is standard idiomatic python:

    [ (student.name, 'A') for student in students if student.grade > 90]

I'd assert that first class functions are idiomatic python as well and are also critical for python programming. They play an integral part of django, for example.

shin_lao2• 16 years ago

I thought the book was to be an introduction to programming through Python, that's a good opportunity to show "by the way, you can also see things the functional way...".

I'm no Python expert, I couldn't say what's idiomatic or not. That being said, I never had the feeling of struggling with the language when using map and filter, quite the contrary.

What's the idiomatic way of doing this?

   suffix_str_lst = map(lambda x: x + "_suffix", str_lst)

araneae2• 16 years ago

Meh. I just sent this to a friend of mine that knows nothing about coding, but is taking a class (biology) that uses python. She really has no need of functional programming, she just needs to know how to survive her problem sets. I think that's the audience.

zedshaw16• 16 years ago

Exactly. I taught programming, not dogma. Frankly, if I can teach two paradigms, and one is easy to explain while the other is hard, well I'm going to teach the easy one to explain.

Functional programming is just hard to explain to people who know next to nothing. Especially in a language like Python where the functional concepts are kind of half-assed.

zedshaw16• 16 years ago

You are not mistaken, there is no chapter on functional programming. Why? Because "The Little Schemer" is a way better book for teaching better functional programming than I could possibly do in a Python book. Python's functional concepts are just not really that great, so I couldn't explain them very well.

illumen• 16 years ago

If you're not teaching pythons functional concepts, then you're not teaching python.

However I think you have accidentally... consider this short example which shows off first class functions, map, reduce, no side effects, and filtering.

  [(lambda a,b,p:(a+p,b+p))(x,y,2) for x in (1,4) for y in (10,15,22) if x*y > 25]

Python does functional programming without people even knowing that it is functional programming :)

MrJagil2• 16 years ago

I am learning python through this book at the moment. It is my first attempt at learning to code, so I have nothing to compare it with, but I must say that this book is very good.

My only gripe is that he poses certain questions/exercises that he fully expects us to solve, one way or another. But if we cannot; we're screwed. He does not give the answer. It has only happened once so far, but that was enough for me to miss out on what seems like a pretty crucial part of the book.

mechanical_fish• 16 years ago

He does not give the answer.

Welcome to graduate school! (And, for that matter, real life.)

As in grad school, the secret is: If you can't figure it out, ask around. Form teams that stay up until 3am waving their hands and sketching on chalkboards. If nothing else, it's a bonding experience that you'll treasure for life.

MrJagil2• 16 years ago

I get your message, but the problem is this is not grad school. This is a book; one way communication. I have no one to ask, as I am the only one I know who has an interest in coding.

Of course I can always ask on the web, but having to break off from coding, pose a question, and then wait for it to get answered before I can continue really breaks up my learning curve.

vidar• 16 years ago

God I miss those times, I seriously need to get into that kind of group again.

BvS3• 16 years ago

Same here. On the one hand it might be a good thing not to give the answers away so you also have to learn to search the web, use stackoverflow... but on the other hand it can be a huge time sink if you just want to know if your solution is correct.

Maybe some kind of forum in addition to the bok would be a good idea.

RyanMcGreal4• 16 years ago

Learning how to find answers to programming questions is by no means a time sink.

jfager• 16 years ago

Did you share that experience with him? He's still writing the book, I'm sure he'd love the feedback.

Luyt2• 16 years ago

The #python IRC channel on FreeNode is a great resource for programmers learning python. (But don't expect to be spoonfed, or have everything served on a silver platter, it'll be greatly appreciated if you can show your efforts (using a pastebin site, don't paste into the channel ;-))).

mikeryan2• 16 years ago

Learning how to Google problems is an important programming skill.

Every programmer in the world is pissed that "I'm not sure - I'd Google It" is not an acceptable answer to a question about "how do I do X in programming language Y". Happens every day.

That being said - a book forum or Q/A section on the site would likely be very helpful. I'm learning Objective-C right now and the book I'm using has a corresponding forum associated which usually has the answers I'm looking for.

zedshaw16• 16 years ago

Hey, can you tell me which ones you got stuck on? I can try give a bit of help either here or in the book.

One thing about those though is that if you can't complete them, then just move on and maybe mark it for later. You should try to figure them out for a bit, but sometimes you just can't and have to come back to it later.

Finally, make sure you have this latest version of the book. I added a small section in the beginning which talks about this, so you might have an older version.

EDIT: Oh I'm assuming you mean the Extra Credits. The lessons you should try really hard to do and figure out before moving on. But skipping Extra Credit is quite alright.

jacobolus3• 16 years ago

One thing you might add to the book is a “what to do if I get stuck” section. I think especially pointing people (even newbies) at IRC is a good idea, as long as there's a bit of elaboration about how to effectively ask IRC questions.

Freenode’s web client http://webchat.freenode.net/ isn’t perfect, but it should be figure-outable when accompanied by some simple directions.

BvS3• 16 years ago

One thing that really took me a long time to figure out was that using python on Windows XP is something different than using it on a mac or on linux. Some things just don#t work or at least work slighlty different. Maybe you could ad a more explicit warning about that.

Example: http://stackoverflow.com/questions/3391998/pydoc-is-not-work...

RexRollman2• 16 years ago

Zed,

May I suggest making it available in other formats, assuming that it is possible, once it is finished? Perhaps as text or HTML files in a tarball? Or even as an epub (for Nooks and iPad)?

midnightmonster• 16 years ago

In the absence of an epub, GoodReader on the ipad is very handy for reading PDFs as books. The type is a little small on this document, but I am able to read it without zooming and panning.

cmsj• 16 years ago

What does GoodReader have over using iBooks? I've mostly just used it for storing manuals for tech products so far, but it seems like a reasonable way to read PDFs.

FraaJad2• 16 years ago

The source files are written in rst(ReStructured Text) format, the standard documentation format for Python. Specifically using [Sphinx](http://sphinx.pocoo.org).

One of the default output formats IS HTML.

Build instructions on *nix:

    $ fossil clone http://learnpythonthehardway.org lpthw.fossil 
    $ mkdir lpthw
    $ cd lpthw
    $ fossil open ../lpthw.fossil 
    $ make html
    $ open _build/html/index.html

To install sphinx:

    $ easy_install sphinx

    $ pip install sphinx

Here you go: a zipped file containing HTML files on google docs. https://docs.google.com/leaf?id=0BzdipdlNhpRrNWNmYjFlNmMtZTl...

RexRollman2• 16 years ago

Thanks. And thanks for showing how to do this as well.

zedshaw16• 16 years ago

Please don't put it online in HTML just yet. I need to get it edited, and I'm afraid people will put versions of the book up in HTML format with errors and problems. Once the book is 1.0 then I'll have it online and anyone else can put it online. Can you take your link down please?

zedshaw16• 16 years ago

Yep, the plan is to create a better site, offer the book on lulu.com in dead tree and ereader formats, and put it up in HTML format.

I won't do any of that yet though because I need to edit it and don't want people getting bad web pages from caches or places.

chrislo• 16 years ago

Also, how about translating to other (programming) languages? Would you be interested in people porting the book, Zed?

steveklabnik5• 16 years ago

He said before he's got a generic domain as well, and would be interested in porting it to other languages, or helping others to do so.

SteveC• 16 years ago

Mongrel 2 and now a book on Python. The man is a machine.

regularfry• 16 years ago

If I remember correctly, he's also currently unemployed. This may be relevant :-)

jonknee• 16 years ago

He does more without a job than most people do with one.

Luyt2• 16 years ago

He's also planning to give python classes: http://codelesson.com/python (discussed in http://news.ycombinator.com/item?id=1724354)

boundlessdreamz• 16 years ago

Wasn't he employed with dropbox?

zedshaw16• 16 years ago

I am, but to be honest, I got more done when I had a job. See all those sites? I did all of those, wrote for them, worked on LPTHW, wrote mulletdb.com, hacked on lamson, a few other projects, and still played guitar about 4 hours a day.

Now that I'm just working on Mongrel2 it feels like I do less. Weird.

mikeryan2• 16 years ago

I don't know why he's wasting time teaching python he could make millions (bwahahaha) giving "getting things done" seminars.

Of course they would probably consist of him saying "find something that pisses you off.Then fix it" over and over.

bmelton3• 16 years ago

I don't know how you got downvoted, but I don't suppose it changes the intent of my reply either way:

That MIGHT just be the secret to Zed's success -- that so much in the world seems to piss him off means that there is so much stuff he feels he needs to fix that he's constantly drowning in the need to fix something.

Some of us are more complacent -- I'm happy to fix the things that irritate me, but my body of work may be less prolific because I'm generally happy with the products that I use.

zedshaw16• 16 years ago

I keep meaning to write some kind of blog about this, but I call it "time opportunism" as opposed to "time management". That's the best name I could come up with for this thing I do that keeps me creative and flexible yet still getting things done.

In a nutshell, I quit trying to explicitly plan and organize my life (not that I was any good at that) and instead I have a giant bag of things I need to do. There's usually a bunch of projects, and each has a todo list. All I do is when I have the time to work on one AND the motivation, then I go bang out as much as I can until I can't. By having lots of different little projects I'm pretty sure I'll always have something to work on that motivates me at that time.

The only caveat on this is I then do one thing at a time. I see too many people who can't get their todo list down are usually trying to do 5 things at once. A good sign you're this kind of person is if you love patch queues. Just do one thing, and make sure before you do it that you can do it. Don't juggle 10 things at once.

steveklabnik5• 16 years ago

Sounds like Structured Procrastination to me.

http://structuredprocrastination.com/

chegra• 16 years ago

I for one would appreciate a blog post on this. I'm pretty sure the rest of the community are there right along side me.

chuhnk• 16 years ago

Thank you for posting this comment. I don't know why but this completely makes me think of context switching in the kernel and everything then becomes clear. I am guilty of "multitasking" and at the end of it accomplishing almost nothing, only recently have I realised the error in my ways. Your recent work and comment are confirmation that focusing on one thing at a time is the way forward when working on substantial tasks.

atomical• 16 years ago

I was looking forward to reading through this until I found out that I will go insane.

-- It was a joke.

VMG2• 16 years ago

The last chapter (Advice From An Old Programmer) is very thought-provoking and slightly unnerving for someone who is studying CS

trop• 16 years ago

It's a lovely chapter! Thanks for pointing it out.

Programming as an intellectual activity is the only art form that allows you to create interactive art. ... . The world needs more weird people who know how things work and who love to ﬁgure it all out.

It's inspiring to see him talking about the beauty of (software) engineering as a means of making which has the quality of an art.

VMG2• 16 years ago

The chilling part is

Programming as a profession is only moderately interesting. It can be a good job, but if you want to make about the same money and be happier you could actually just go run a fast food joint. You are much better off using code as your secret weapon in another profession.

People who can code in the world of technology companies are a dime a dozen and get no respect. People who can code in biology, medicine, government, sociology, physics, history, and mathematics are respected and can do amazing things to advance those disciplines.

I have always had the suspicion that this is the case but now I have some validation

jamie_ca• 16 years ago

Nice, but that's an annoying license. I'm tempted into porting his assignments to Ruby, but do to licensing I'll need to do them completely separately - I can't make a cohesive document out of it.

Ah well. His prerogative I suppose. Just makes me feel like "teaching people to program" isn't his primary goal.

zedshaw16• 16 years ago

Don't copy, imitate. The book was very easy to write. Just lay out 52 exercises, 26 for super basic stuff, 26 for progressively more advanced stuff. Take about an hour or two every night and write a couple. Pretty simple really. You may not have my style in your writing, but you'll definitely get a book that is more Ruby than what I've written.

One warning though, if you think it'll be better to have the book crowdsourced, think again. Programmers seem to be pretty bad at teaching programming, so it's best to just write your book and have people give you feedback as you go.

utefan001• 16 years ago

I have read the first 20 pages. Excellent! Very well done. Great advice. Fun / proven way to learn. Thanks Zed!!

zedshaw16• 16 years ago

You're welcome. Remember if you run into errors, just submit a ticket for it on the learnpythonthehardway.org web site and I'll fix them up.

gbrindisi• 16 years ago

I am training myself in Python with this book from a week or so.

I know how to code in other languages and programming basic so I am not a first time coder... yet this little book is absolutely useful and I am enjoying it exercise after exercise.

Learning trough practice FTW!

Thank you Zed.

zedshaw16• 16 years ago

Fantastic. Keep on plugging through and if you hit any problems just ask me. I'm on twitter @zedshaw so just ask and I'll help.

emehrkay2• 16 years ago

Very nice. I just randomly choose to view the arguments unpacking section and found a defect (no example given on pg 36 for passing in only two args instead of all three, but later cited as "see how I passed in two args"). Created a ticket.

zedshaw16• 16 years ago

Thanks, I think I fixed it but the ticket is kind of vague:

http://learnpythonthehardway.org/tktview/08a86ff3098eae91d8c...

Update it for me if I didn't understand what you think should be done.

emehrkay2• 16 years ago

Yeah that's it exactly. You never show

    python script.py only two_args

Just the traceback. It might be confusing to a newbie.

statictype• 16 years ago

Loved the final chapter.

At the end of the day, it's not about functions or closures or monads. It's about building something interesting or useful. Whether you used php or arc is not relevant.

Tarks• 16 years ago

Thankyou Zed, I'm going to give this a proper read-through before probably using it to help teach a friend how to learn to program.

zeemonkee• 16 years ago

I recommended this to a new hire (frontend HTML/JS guy, but wants to learn Python). He really found it easy to get into, and appreciated the exercises. Thanks for publishing it.

Zed finishes Learn Python The Hard Way

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