10 ms·

Learning to Program: Why Python?

94 points by camlinke 14y ago

hkmurakami 14y ago
>The similarities between these languages are as complete as the similarities between driving in Europe and America: In the same way an experienced driver from one continent can improvise with a reasonable degree of safety on the other, an experienced Python programmer can be up-and-running with C# in a day or two. Absolutely love the analogy. It's a great display of leveraging the English language to convey complex concepts in a down-to-earth fashion. Even as engineers (or perhaps because we are engineers), getting our ideas across in understandable, layman terms is a potent weapon. (though admittedly, the latter part of the excerpt could perhaps be simplified)
- villagefool 14y ago
  But that doesn't explain why Python and not C#. Can't a C# programmer be up-and-running with Python in a day or two too?
  - cgh 14y ago
    Probably because not everyone is learning to program on Windows.
    - jiggy2011 14y ago
      You can use Mono to program C# on Linux or Mac.
      - spamizbad 14y ago
        Yeah, but chances are your Linux or Mac users will already have python installed via their OS. The biggest challenge for Windows users is remembering to go to python.org and not python.com to obtain their version.
        eichin 14y ago
        And if you look at any of the udacity office-hours videos, when you see laptops, they're almost always Macs :-)
      - anthonyb 14y ago
        This is for people learning to program, remember? If they have to install Mono, that's just an extra hurdle, and doesn't get them any closer to their goal vs. just using Python.
        jiggy2011 14y ago
        Either way your going to have to install something, either a python runtime or a mono/.net runtime. Plus your going to at least want to install a better text editor and probably set some environment variables. The installation process for all of these things shouldn't be a big hurdle since all you'd have to do is follow a set of steps that can be easily demonstrated.
  - jiggy2011 14y ago
    Yes, probably. The point is that Python has a lower barrier to entry, mainly because it doesn't force you to learn anything about OO first. That is why python and not C#. The point is being made that learning one language makes it vastly easiest to learn another , so you may as well start by learning one that is designed to be learnable rather than necessarily one that is in demand.
  - antidoh 14y ago
    Python has less syntactic sugar: semi colon-terminated statements, braces, etc. It doesn't make Python "better," but to a newb, the less the better. If less comes in a real language, so much the better. Variable declarations ... you could go either way. I like that Python is closer to a language that "knows what you mean" even when you don't declare a variable. You can learn discipline later. Learning to program is a chicken and egg problem, you have to learn two things: a language (any language) and programming concepts, and unfortunately you have to learn one to do the other. Python's forgiving nature makes that a bit easier than some other languages.
horsehead 14y ago
I just want to say that I've been learning Python as my first language. I've found it to be fairly intuitive and a lot of fun. Of course, learning any language, especially your first, is going to be difficult, though. One of the drawbacks I've heard is that Python subscribes to the idea of doing something 'the right way,' although i've found a few times where i did something the 'not right way' and it was still functional (although maybe a little longer or not as clean as it could have been). Edit: I've also been involved a little bit with Ruby lately, and it seems thre are a few similarities between the two. Though that could just be that there are many similarities between any two langauges, and I'm just not familiar enough with multiple languages to realize that :P Still, it's an excellent first language, IMO
- fusiongyro 14y ago
  A lack of freedom can be a good thing in a first language. Of course, Python doesn't always have a "right way" or they wouldn't be on their fourth command line argument parsing library. ;) Ruby and Python will seem more similar after knowing a lot of languages. But they are different enough too. If it's not intimidating you it's probably a good second language.
  - slurgfest 14y ago
    Why do I keep reading about this? I don't see how any command line argument parsing library is relevant other than argparse. Do you have some concrete complaint about argparse? I am seriously wondering what I am missing, it seems so simple to me yet this seems to be a burning perennial complaint.
    - gvalkov 14y ago
      Why shouldn't they be relevant? Getopt is still very useful for short scripts and optparse does everything it was meant to do, even if it's not as full of features as argparse. Maybe argparse really should be the canonical choice, but I certainly wouldn't want to see the others gone. As for a minor complaint about argparse - setting up a custom help formatter [1] is not straightforward, not in the slightest in comparison to optparse [2] (which is much simpler, implementation wise). [1] http://hg.python.org/cpython/file/default/Lib/argparse.py#l144 http://hg.python.org/cpython/file/default/Lib/argparse.py#l1... [2] http://hg.python.org/cpython/file/2.7/Lib/optparse.py#l155 http://hg.python.org/cpython/file/2.7/Lib/optparse.py#l155
idleloops 14y ago
Title is misleading. The article discusses why learn Python instead of C# as a first language. Missing: Python being cross platform (arguably more so than C#.)
Wickk 14y ago
Thought the article was going to be a question as to why. But I wholeheartedly agree as to why Python is a great forst language. The simple fact that it's syntax light will always be the #1 reason it's a great introduction. Worry about the syntactical hangups once you have the core concepts of programming down. I never understood those CS courses that have you diving in blind with C++
- evincarofautumn 14y ago
  Agreed. I may not be a fan of Python in general, but it is a good language for instruction for precisely that reason: less incidental complication so you can focus on inherent complexity. As someone who’s well versed in C++, and who had to tutor CS students in it, I certainly wouldn’t recommend anyone use C++ unless they already know it and can use it effectively.
- commandar 14y ago
  >I never understood those CS courses that have you diving in blind with C++ C++ made more sense to me than all the CS programs that were switching to Java for their intro to CS courses when I was coming up a decade ago. C/C++ may have overhead that's confusing to a beginner out of the gate, but Java just amplifies that.
  - Wickk 14y ago
    Everyone learns differently, so hey to each their own. I dabbled for years throught my HS life in php, but when it came time to actually learn I was completely put off by my first intro to CS course that used the aforementioned 'Dive head first w/ C++!' method and left the course, and was one of 18 to do so. Started learning python on my own around age 19 and everything just skyroketed from there. I'm much more comfortable using( saying that lightly ) C++ these days but I can't imagine ever recommending it to even an enemy as their first language. An aquaintenance on a board somewhere put it best, " C++ is like a hurricane. Gorgeous but incredibly destructive". Personally I think it all looks hideous but I get the point now.
    - 14y ago
10098 14y ago
I never quite understood why people think that teaching beginners programming through languages like Python and C# is a good idea. It's really hard. Think about it. It may seem easy to start writing programs in those languages, but understanding what is actually going on is sort of difficult for someone who has no idea how things work. When you're implementing a linked list or a binary search tree for the first time, it's important to understand how your data structure is laid out in memory, otherwise it's a pointless exercise. Higher-level languages are convenient, but they hide a lot of what is going on, and that, in my opinion, is bad, if you are learning. I think the best language to start with is C (and not C++, of course). One must understand pointers and bytes and bits and memory management and all that shit that leads to segfaults and many hours of debugging to be a programmer. I would even go as far as to say that one should start with an assembler and not C, but given the immense complexity of contemporary hardware, I understand that such approach is infeasible. However, teaching kids programming with a physical (not emulated), really simple, toy CPU is probably a good idea. Too bad I don't know any such CPUs.
- scott_s 14y ago
  I would even go as far as to say that one should start with an assembler and not C, but given the immense complexity of contemporary hardware, I understand that such approach is infeasible. Someone could make a similar argument about starting in C. And make similar arguments that you made for the benefits. You have to start teaching somewhere in the stack. I actually disagree that it's infeasible to start with assembly. I don't think it's wise, but it's certainly feasible. I think people tend to have a bias that beginners should start at the same level of abstraction that they did. But I think that in online discussions, we place too much emphasis on where to start. I doubt it matters as much as the other factors, such as motivation of the student and the patience and care of the instructor.
- jodoherty 14y ago
  Why not just start with some embedded development then? 8-bit PIC and AVR microcontrollers have very simple instruction sets and can be connected to simple I/O devices like switches and LEDs, but they both use Harvard architectures, so you have different address spaces for code and data. The newer 32-bit PIC micros use a MIPS core, but the development tools aren't very open, despite being based on GCC. The 16-bit MSP430 is fairly simple, has good open-source development tools, cheap development hardware (check out the Launchpad), and a more conventional von-Neumann architecture. Check out some of Michael Kohn's sample code for the msp430 assembler he wrote: http://www.mikekohn.net/micro/naken430asm_msp430_assembler.php http://www.mikekohn.net/micro/naken430asm_msp430_assembler.p...
salimmadjd 14y ago
Right idea, but bad execution. This could have been a great post had the OA had expanded on his examples instead of just linking to wikipedia. Here is where he failed. We need to ask, who is this article for? Programmers who already understands some of the patterns and paradigms OA touched upon, or newbies. Given he seem to be responding to a new programmer, it would have been more effective if OA had displayed the C# implementation vs. python, at least for a few of the more interesting examples. On a personal perspective, the first language I thought myself was BASIC. Remember line numbers and goto? I later learned enough C to understand how things work behind the scene. So I personally like the high-level first approach, especially python. It's like a swiss army knife.
smortaz 14y ago
The author mentions that C# has a nice IDE (Visual Studio). I'd like to mention that a couple of OSS & Python enthusiasts at msft have produced one for Python as well (free/apache 2.0). It supports both CPython and IronPython, along with intellisense, debugging, profiling, etc. : http://pytools.codeplex.com http://pytools.codeplex.com
gbog 14y ago
Liked the fair simplicity of the post but I am disappointed by the Wikipedia links. Like many design pattern they look like Java special idioms used to overcome its limitations. So dependency injection is just "if x import y"? Like any other conditional, it must be used only if necessary but does it need be a Design Pattern?
- evincarofautumn 14y ago
  Design patterns tend to arise due to linguistic limitations, but not always. They’re mainly a shared vocabulary for talking about software architecture and design, regardless of paradigm. As for dependency injection: DI ⊆ inversion of control ⊆ decoupling ⊆ factoring, where ⊆ = “is a kind of”. Roughly, DI means externalising dependencies and giving them as parameters in order to reduce coupling. Which, when you put it that way, is obvious, and something we (should) do often in any language.
Permit 14y ago
>Python’s type system is more flexible than C#’s (for better and worse). It is important to keep in mind a few concepts from Python that are not directly translated to C#:... >Dynamic typing, a.k.a “duck-typing” (this, too, can be accomplished using libraries built around Delegate.DynamicInvoke). I'm not super familiar with the keyword, but I'm fairly sure this is built right into C# 4.0 via the "dynamic" keyword, is it not?
- davidlumley 14y ago
  From what I understand, yes. I believe the point the author is trying to make however, is that Python allows you to think more about the structure/function of your code rather than worrying if a variable should be an integer, a float, or a double making it easier for new programmers to "jump in".
wizardhat 14y ago
Here's one reason why not: no anonymous functions longer than one line. Which is a pretty lame limitation for a modern high-level language, all due to the dumb whitespace-as-scope design.
- simondlr 14y ago
  Honest question: If you are making an anonymous function longer than one line, shouldn't you just make a normal function? What are the use cases for large anonymous functions?
  - jerf 14y ago
    Especially in a learning context, I have no problem with requiring decent names for functions. It's a learning context, not a professional one. This strikes me as like complaining that your carpentry class won't be covering a particularly exotic tool only favored by a quarter of professional carpenters anyhow. No, it's not a fatal objection to the class. If the tool is so wonderful they'll find out about it later. After they've become familiar with things like "hammers" and "nails" and the pounding thereof, which is the real problem they face today.
  - chubot 14y ago
    I wrote a nonblocking library (for pipes/processes/signals) in Python like node.js. So many of the callbacks end up being inner functions (they don't when you decide you can make all the necessary state object-level, and thus make the callback a method). The anonymous syntax actually reads better than defining an inner function and then calling it. I think the real reason why they were never added is syntax, and honestly I can't think of a good syntax myself.
    - simondlr 14y ago
      That makes sense. Callback methods. Thanks.
  - tikhonj 14y ago
    Simplest case: custom control structures. In JavaScript, a broadly comparable language, I mainly use anonymous functions for event handling and map/each/fold. They are also useful for implementing more advanced code like arrows cleanly. In a lot of ways the anonymous function in these cases is more akin to a block than a named function--it's only used once and in a very clear place. Having to name my click and onload handlers would make the code more confusing. Coincidentally, this brings me to something that annoys me in both languages: lambdas are too verbose. Having much simpler and more concise lambda syntax (I'm personally a fan of Haskell's \ x -> x because it looks like a lambda if you squint) would make a lot of common idioms more readable and would encourage wider use of custom control abstractions, which can significantly improve code. Amusingly I don't find myself using lambda syntax nearly as much in Haskell despite the fact that it looks really nice. A surprising amount of the time simple point-free code is all that's needed, and anything too complex gets moved into a where clause. But Haskell is not really comparable with JavaScript/Python at all.
cageface 14y ago
It's too bad Javascript's faults are so grievous. The sane subset of JS + a web browser makes a pretty good beginners environment. But when you have to blow so much time on screwy things like "this" scoping and unwanted implicit conversions it kind of tips the balance.
- jerf 14y ago
  You can always do something like this: http://www.skulpt.org/ http://www.skulpt.org/ None of the disadvantages of such an approach matter in a learning context. Sure, it's slow relative to a real implementation... but so what? (I'm also not saying that particular link is a drop-in solution, as I've never heard of it until I went googling on the theory that something like it must exist. But if you were building a business on this, it looks far enough along that you could adapt it as needed.)
simonh 14y ago
I've been playing with Codea on the iPad for a few days. I'm a big Python fan, but having never used Lua before I have to say it's a great little language and Codea is a lovely learning environment. My daughter (8) was watching me play with it on the couch at the weekend and I let her change some of the variable values, pick colours, etc and see the difference it made when we ran the program.
tikhonj 14y ago
I can't help thinking that almost everything he lists applies more to Scheme than Python. Scheme also has the advantage of being much simpler, smaller, more concise, more flexible and more elegant than Python. It actually does functional programming well rather than half-heartedly, and is rather nice for OOP as well. Additionally, Scheme has one very important property that Python lacks--there is almost no magic. Even definitions and assignments (define and set! respectively) look like normal function calls. It also makes it clear that very little is fundamental to a language--with Java and Python things like classes and control structures are special and built into the language; with Scheme they do not differ superficially from normal functions. With Java I thought classes and objects were somehow the only way to do it; Scheme clearly showed me that they do not even have to be part of the core language. Now, Scheme does have some complicated ideas like macros and continuations, but there is no reason to teach those to beginners--it's an eminently useful language as is, and extremely simple. The very first CS course I took in college used Scheme; we spent something like just two lectures on the language itself. Now that the professor retired they've changed the course over to Python; I think they're still learning the language half-way through the semester. Scheme is also great because, being very simple, it is much easier to implement than Python. And once you have a basic Scheme implementation, you can modify it to see other potential languages. For example, in our intro CS course, we talked about writing a memoizing interpreter and even a lazy interpreter. It's hard to imagine a lazy Python! We even reused Scheme syntax (but not really semantics) to cover logic programming à la Prolog. That course was one of the most enlightening semesters I have ever spent. I really think that Scheme is the perfect introductory didactic language.
- Derbasti 14y ago
  It makes sense to use a language that is close to what people will be using later just so they will be able to transfer their learned knowledge more easily. Lisps are very interesting and important, but their syntax does not transfer easily to most popular languages.
- driax 14y ago
  I never really accepted the argument that Scheme/Lisp is simpler than a language like Python, simply because everything in the language is reduced to constants/terminals (what's the right terminology here?) and functions. Many language differantiate between statement and expression, and compile-time and runtime and lots of other stuff. Saying that we can express C-structs in a language by reducing them to functions is not a simplification, instead I would argue it's worse when trying to grok C. While coming from Python it would be easier since we already have classes, and C-structs are simply compile-time final classes without inheritance. I agree though that learning Scheme can teach a lot, just not necessarily how to grok every other language well.

94 points by camlinke 14y ago

>The similarities between these languages are as complete as the similarities between driving in Europe and America: In the same way an experienced driver from one continent can improvise with a reasonable degree of safety on the other, an experienced Python programmer can be up-and-running with C# in a day or two. Absolutely love the analogy. It's a great display of leveraging the English language to convey complex concepts in a down-to-earth fashion. Even as engineers (or perhaps because we are engineers), getting our ideas across in understandable, layman terms is a potent weapon. (though admittedly, the latter part of the excerpt could perhaps be simplified)

villagefool 14y ago
But that doesn't explain why Python and not C#. Can't a C# programmer be up-and-running with Python in a day or two too?
- cgh 14y ago
  Probably because not everyone is learning to program on Windows.
  - jiggy2011 14y ago
    You can use Mono to program C# on Linux or Mac.
    - spamizbad 14y ago
      Yeah, but chances are your Linux or Mac users will already have python installed via their OS. The biggest challenge for Windows users is remembering to go to python.org and not python.com to obtain their version.
      - eichin 14y ago
        And if you look at any of the udacity office-hours videos, when you see laptops, they're almost always Macs :-)
    - anthonyb 14y ago
      This is for people learning to program, remember? If they have to install Mono, that's just an extra hurdle, and doesn't get them any closer to their goal vs. just using Python.
      - jiggy2011 14y ago
        Either way your going to have to install something, either a python runtime or a mono/.net runtime. Plus your going to at least want to install a better text editor and probably set some environment variables. The installation process for all of these things shouldn't be a big hurdle since all you'd have to do is follow a set of steps that can be easily demonstrated.
- jiggy2011 14y ago
  Yes, probably. The point is that Python has a lower barrier to entry, mainly because it doesn't force you to learn anything about OO first. That is why python and not C#. The point is being made that learning one language makes it vastly easiest to learn another , so you may as well start by learning one that is designed to be learnable rather than necessarily one that is in demand.
- antidoh 14y ago
  Python has less syntactic sugar: semi colon-terminated statements, braces, etc. It doesn't make Python "better," but to a newb, the less the better. If less comes in a real language, so much the better. Variable declarations ... you could go either way. I like that Python is closer to a language that "knows what you mean" even when you don't declare a variable. You can learn discipline later. Learning to program is a chicken and egg problem, you have to learn two things: a language (any language) and programming concepts, and unfortunately you have to learn one to do the other. Python's forgiving nature makes that a bit easier than some other languages.

horsehead 14y ago

I just want to say that I've been learning Python as my first language. I've found it to be fairly intuitive and a lot of fun. Of course, learning any language, especially your first, is going to be difficult, though. One of the drawbacks I've heard is that Python subscribes to the idea of doing something 'the right way,' although i've found a few times where i did something the 'not right way' and it was still functional (although maybe a little longer or not as clean as it could have been). Edit: I've also been involved a little bit with Ruby lately, and it seems thre are a few similarities between the two. Though that could just be that there are many similarities between any two langauges, and I'm just not familiar enough with multiple languages to realize that :P Still, it's an excellent first language, IMO

fusiongyro 14y ago
A lack of freedom can be a good thing in a first language. Of course, Python doesn't always have a "right way" or they wouldn't be on their fourth command line argument parsing library. ;) Ruby and Python will seem more similar after knowing a lot of languages. But they are different enough too. If it's not intimidating you it's probably a good second language.
- slurgfest 14y ago
  Why do I keep reading about this? I don't see how any command line argument parsing library is relevant other than argparse. Do you have some concrete complaint about argparse? I am seriously wondering what I am missing, it seems so simple to me yet this seems to be a burning perennial complaint.
  - gvalkov 14y ago
    Why shouldn't they be relevant? Getopt is still very useful for short scripts and optparse does everything it was meant to do, even if it's not as full of features as argparse. Maybe argparse really should be the canonical choice, but I certainly wouldn't want to see the others gone. As for a minor complaint about argparse - setting up a custom help formatter [1] is not straightforward, not in the slightest in comparison to optparse [2] (which is much simpler, implementation wise). [1] http://hg.python.org/cpython/file/default/Lib/argparse.py#l144 http://hg.python.org/cpython/file/default/Lib/argparse.py#l1... [2] http://hg.python.org/cpython/file/2.7/Lib/optparse.py#l155 http://hg.python.org/cpython/file/2.7/Lib/optparse.py#l155

idleloops 14y ago

Title is misleading. The article discusses why learn Python instead of C# as a first language. Missing: Python being cross platform (arguably more so than C#.)

Wickk 14y ago

Thought the article was going to be a question as to why. But I wholeheartedly agree as to why Python is a great forst language. The simple fact that it's syntax light will always be the #1 reason it's a great introduction. Worry about the syntactical hangups once you have the core concepts of programming down. I never understood those CS courses that have you diving in blind with C++

evincarofautumn 14y ago
Agreed. I may not be a fan of Python in general, but it is a good language for instruction for precisely that reason: less incidental complication so you can focus on inherent complexity. As someone who’s well versed in C++, and who had to tutor CS students in it, I certainly wouldn’t recommend anyone use C++ unless they already know it and can use it effectively.
commandar 14y ago
>I never understood those CS courses that have you diving in blind with C++ C++ made more sense to me than all the CS programs that were switching to Java for their intro to CS courses when I was coming up a decade ago. C/C++ may have overhead that's confusing to a beginner out of the gate, but Java just amplifies that.
- Wickk 14y ago
  Everyone learns differently, so hey to each their own. I dabbled for years throught my HS life in php, but when it came time to actually learn I was completely put off by my first intro to CS course that used the aforementioned 'Dive head first w/ C++!' method and left the course, and was one of 18 to do so. Started learning python on my own around age 19 and everything just skyroketed from there. I'm much more comfortable using( saying that lightly ) C++ these days but I can't imagine ever recommending it to even an enemy as their first language. An aquaintenance on a board somewhere put it best, " C++ is like a hurricane. Gorgeous but incredibly destructive". Personally I think it all looks hideous but I get the point now.
  - 14y ago

10098 14y ago

I never quite understood why people think that teaching beginners programming through languages like Python and C# is a good idea. It's really hard. Think about it. It may seem easy to start writing programs in those languages, but understanding what is actually going on is sort of difficult for someone who has no idea how things work. When you're implementing a linked list or a binary search tree for the first time, it's important to understand how your data structure is laid out in memory, otherwise it's a pointless exercise. Higher-level languages are convenient, but they hide a lot of what is going on, and that, in my opinion, is bad, if you are learning. I think the best language to start with is C (and not C++, of course). One must understand pointers and bytes and bits and memory management and all that shit that leads to segfaults and many hours of debugging to be a programmer. I would even go as far as to say that one should start with an assembler and not C, but given the immense complexity of contemporary hardware, I understand that such approach is infeasible. However, teaching kids programming with a physical (not emulated), really simple, toy CPU is probably a good idea. Too bad I don't know any such CPUs.

scott_s 14y ago
I would even go as far as to say that one should start with an assembler and not C, but given the immense complexity of contemporary hardware, I understand that such approach is infeasible. Someone could make a similar argument about starting in C. And make similar arguments that you made for the benefits. You have to start teaching somewhere in the stack. I actually disagree that it's infeasible to start with assembly. I don't think it's wise, but it's certainly feasible. I think people tend to have a bias that beginners should start at the same level of abstraction that they did. But I think that in online discussions, we place too much emphasis on where to start. I doubt it matters as much as the other factors, such as motivation of the student and the patience and care of the instructor.
jodoherty 14y ago
Why not just start with some embedded development then? 8-bit PIC and AVR microcontrollers have very simple instruction sets and can be connected to simple I/O devices like switches and LEDs, but they both use Harvard architectures, so you have different address spaces for code and data. The newer 32-bit PIC micros use a MIPS core, but the development tools aren't very open, despite being based on GCC. The 16-bit MSP430 is fairly simple, has good open-source development tools, cheap development hardware (check out the Launchpad), and a more conventional von-Neumann architecture. Check out some of Michael Kohn's sample code for the msp430 assembler he wrote: http://www.mikekohn.net/micro/naken430asm_msp430_assembler.php http://www.mikekohn.net/micro/naken430asm_msp430_assembler.p...

salimmadjd 14y ago

Right idea, but bad execution. This could have been a great post had the OA had expanded on his examples instead of just linking to wikipedia. Here is where he failed. We need to ask, who is this article for? Programmers who already understands some of the patterns and paradigms OA touched upon, or newbies. Given he seem to be responding to a new programmer, it would have been more effective if OA had displayed the C# implementation vs. python, at least for a few of the more interesting examples. On a personal perspective, the first language I thought myself was BASIC. Remember line numbers and goto? I later learned enough C to understand how things work behind the scene. So I personally like the high-level first approach, especially python. It's like a swiss army knife.

smortaz 14y ago

The author mentions that C# has a nice IDE (Visual Studio). I'd like to mention that a couple of OSS & Python enthusiasts at msft have produced one for Python as well (free/apache 2.0). It supports both CPython and IronPython, along with intellisense, debugging, profiling, etc. : http://pytools.codeplex.com http://pytools.codeplex.com

gbog 14y ago

Liked the fair simplicity of the post but I am disappointed by the Wikipedia links. Like many design pattern they look like Java special idioms used to overcome its limitations. So dependency injection is just "if x import y"? Like any other conditional, it must be used only if necessary but does it need be a Design Pattern?

evincarofautumn 14y ago
Design patterns tend to arise due to linguistic limitations, but not always. They’re mainly a shared vocabulary for talking about software architecture and design, regardless of paradigm. As for dependency injection: DI ⊆ inversion of control ⊆ decoupling ⊆ factoring, where ⊆ = “is a kind of”. Roughly, DI means externalising dependencies and giving them as parameters in order to reduce coupling. Which, when you put it that way, is obvious, and something we (should) do often in any language.

Permit 14y ago

>Python’s type system is more flexible than C#’s (for better and worse). It is important to keep in mind a few concepts from Python that are not directly translated to C#:... >Dynamic typing, a.k.a “duck-typing” (this, too, can be accomplished using libraries built around Delegate.DynamicInvoke). I'm not super familiar with the keyword, but I'm fairly sure this is built right into C# 4.0 via the "dynamic" keyword, is it not?

davidlumley 14y ago
From what I understand, yes. I believe the point the author is trying to make however, is that Python allows you to think more about the structure/function of your code rather than worrying if a variable should be an integer, a float, or a double making it easier for new programmers to "jump in".

wizardhat 14y ago

Here's one reason why not: no anonymous functions longer than one line. Which is a pretty lame limitation for a modern high-level language, all due to the dumb whitespace-as-scope design.

simondlr 14y ago
Honest question: If you are making an anonymous function longer than one line, shouldn't you just make a normal function? What are the use cases for large anonymous functions?
- jerf 14y ago
  Especially in a learning context, I have no problem with requiring decent names for functions. It's a learning context, not a professional one. This strikes me as like complaining that your carpentry class won't be covering a particularly exotic tool only favored by a quarter of professional carpenters anyhow. No, it's not a fatal objection to the class. If the tool is so wonderful they'll find out about it later. After they've become familiar with things like "hammers" and "nails" and the pounding thereof, which is the real problem they face today.
- chubot 14y ago
  I wrote a nonblocking library (for pipes/processes/signals) in Python like node.js. So many of the callbacks end up being inner functions (they don't when you decide you can make all the necessary state object-level, and thus make the callback a method). The anonymous syntax actually reads better than defining an inner function and then calling it. I think the real reason why they were never added is syntax, and honestly I can't think of a good syntax myself.
  - simondlr 14y ago
    That makes sense. Callback methods. Thanks.
- tikhonj 14y ago
  Simplest case: custom control structures. In JavaScript, a broadly comparable language, I mainly use anonymous functions for event handling and map/each/fold. They are also useful for implementing more advanced code like arrows cleanly. In a lot of ways the anonymous function in these cases is more akin to a block than a named function--it's only used once and in a very clear place. Having to name my click and onload handlers would make the code more confusing. Coincidentally, this brings me to something that annoys me in both languages: lambdas are too verbose. Having much simpler and more concise lambda syntax (I'm personally a fan of Haskell's \ x -> x because it looks like a lambda if you squint) would make a lot of common idioms more readable and would encourage wider use of custom control abstractions, which can significantly improve code. Amusingly I don't find myself using lambda syntax nearly as much in Haskell despite the fact that it looks really nice. A surprising amount of the time simple point-free code is all that's needed, and anything too complex gets moved into a where clause. But Haskell is not really comparable with JavaScript/Python at all.

cageface 14y ago

It's too bad Javascript's faults are so grievous. The sane subset of JS + a web browser makes a pretty good beginners environment. But when you have to blow so much time on screwy things like "this" scoping and unwanted implicit conversions it kind of tips the balance.

jerf 14y ago
You can always do something like this: http://www.skulpt.org/ http://www.skulpt.org/ None of the disadvantages of such an approach matter in a learning context. Sure, it's slow relative to a real implementation... but so what? (I'm also not saying that particular link is a drop-in solution, as I've never heard of it until I went googling on the theory that something like it must exist. But if you were building a business on this, it looks far enough along that you could adapt it as needed.)

simonh 14y ago

I've been playing with Codea on the iPad for a few days. I'm a big Python fan, but having never used Lua before I have to say it's a great little language and Codea is a lovely learning environment. My daughter (8) was watching me play with it on the couch at the weekend and I let her change some of the variable values, pick colours, etc and see the difference it made when we ran the program.

tikhonj 14y ago

I can't help thinking that almost everything he lists applies more to Scheme than Python. Scheme also has the advantage of being much simpler, smaller, more concise, more flexible and more elegant than Python. It actually does functional programming well rather than half-heartedly, and is rather nice for OOP as well. Additionally, Scheme has one very important property that Python lacks--there is almost no magic. Even definitions and assignments (define and set! respectively) look like normal function calls. It also makes it clear that very little is fundamental to a language--with Java and Python things like classes and control structures are special and built into the language; with Scheme they do not differ superficially from normal functions. With Java I thought classes and objects were somehow the only way to do it; Scheme clearly showed me that they do not even have to be part of the core language. Now, Scheme does have some complicated ideas like macros and continuations, but there is no reason to teach those to beginners--it's an eminently useful language as is, and extremely simple. The very first CS course I took in college used Scheme; we spent something like just two lectures on the language itself. Now that the professor retired they've changed the course over to Python; I think they're still learning the language half-way through the semester. Scheme is also great because, being very simple, it is much easier to implement than Python. And once you have a basic Scheme implementation, you can modify it to see other potential languages. For example, in our intro CS course, we talked about writing a memoizing interpreter and even a lazy interpreter. It's hard to imagine a lazy Python! We even reused Scheme syntax (but not really semantics) to cover logic programming à la Prolog. That course was one of the most enlightening semesters I have ever spent. I really think that Scheme is the perfect introductory didactic language.

Derbasti 14y ago
It makes sense to use a language that is close to what people will be using later just so they will be able to transfer their learned knowledge more easily. Lisps are very interesting and important, but their syntax does not transfer easily to most popular languages.
driax 14y ago
I never really accepted the argument that Scheme/Lisp is simpler than a language like Python, simply because everything in the language is reduced to constants/terminals (what's the right terminology here?) and functions. Many language differantiate between statement and expression, and compile-time and runtime and lots of other stuff. Saying that we can express C-structs in a language by reducing them to functions is not a simplification, instead I would argue it's worse when trying to grok C. While coming from Python it would be easier since we already have classes, and C-structs are simply compile-time final classes without inheritance. I agree though that learning Scheme can teach a lot, just not necessarily how to grok every other language well.