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C4 – C in 4 functions

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Re: C4 – C in 4 functions

#61

Post by metaobject »

abecedarius wrote: post #54
dabockster wrote: post #51

Earlier quoted context omitted.

complaints that it's unreadable are unfounded Not exactly. You have to remember that language and compiler design require a LOT of work and experience to understand, and that many programmers will only see this as, frankly, spaghetti. I think it could have used some more block comments, but that's just me.

I'm writing a chapter for AOSA on something like this: a self-hosting compiler of a subset of Python to Python bytecode. It'll present the full code (about the same length) and try to explain it well for people not into compilers yet, but in the meantime I recommend the Wirth book. What's your favorite shorter intro? I'd especially like to reference other educational compilers that are self-hosting.

So, there is another version of Architecture of Open Source Applications in the works? I love the first two editions - they are unique books that really are gems. Are you able to divulge what projects are covered in the new version?

Re: C4 – C in 4 functions

#63

Post by anigbrowl »

dabockster wrote: post #51
abecedarius wrote: post #23

On a first skim, this looks really nice; complaints that it's unreadable are unfounded. The background that makes it readable are Wirth's Compiler Construction http://www.ethoberon.ethz.ch/WirthPubl/CBEAll.pdf plus precedence climbing http://en.wikipedia.org/wiki/Operator-precedence_parser#Prec...

complaints that it's unreadable are unfounded Not exactly. You have to remember that language and compiler design require a LOT of work and experience to understand, and that many programmers will only see this as, frankly, spaghetti. I think it could have used some more block comments, but that's just me.

I had the same first instinct, but given that a) it's very very tidy code and b) if you want to understand the inner workings of a compiler then you really do need to figure this out, I decided on review that it's basically self-documenting.

Of course figuring out what it's doing is one thing - understanding why it is done in this particular way is another, and while I was able to find my way around fairly quickly I'd cry if I had to re-implement it. I do love how small it is though, that gives it great educational value.

Re: C4 – C in 4 functions

#64

Post by blinks »

anigbrowl wrote: post #63
dabockster wrote: post #51

Earlier quoted context omitted.

complaints that it's unreadable are unfounded Not exactly. You have to remember that language and compiler design require a LOT of work and experience to understand, and that many programmers will only see this as, frankly, spaghetti. I think it could have used some more block comments, but that's just me.

I had the same first instinct, but given that a) it's very very tidy code and b) if you want to understand the inner workings of a compiler then you really do need to figure this out, I decided on review that it's basically self-documenting. Of course figuring out what it's doing is one thing - understanding why it is done in this particular way is another, and while I was able to find my way around fairly quickly I'…

> understanding why it is done in this particular way is another

Isn't that the reason for comments in the first place?

Re: C4 – C in 4 functions

#65

Post by anigbrowl »

blinks wrote: post #64
anigbrowl wrote: post #63

Earlier quoted context omitted.

I had the same first instinct, but given that a) it's very very tidy code and b) if you want to understand the inner workings of a compiler then you really do need to figure this out, I decided on review that it's basically self-documenting. Of course figuring out what it's doing is one thing - understanding why it is done in this particular way is another, and while I was able to find my way around fairly quickly I'…

> understanding why it is done in this particular way is another Isn't that the reason for comments in the first place?

I look to comments to tell me what a block of code is doing rather than why, eg 'Performs a Discrete Cosine Transform on the contents of the buffer' or 'Bubble sort algorithm rearranges the records in at least as much time as required to enjoy a nice cup of tea.'

The 'why' of a very low-level tools like this is the sort of thing that needs to be explored at length in a paper or (in this case) a book, otherwise they'll swamp the actual code. Sometimes as a learning exercise I'll take something like this and comment the hell out of everything, but the value there is more in writing the comments than trying to read them again later. Of course this is very much a matter of personal taste.

Re: C4 – C in 4 functions

#66

Post by nikki93 »

marcofiset wrote: post #4

I honestly think this is ridiculous. Sure, this is an incredible feat, and congrats. But serioulsy, I would be ashamed to publish such unreadable code under my name. What about naming your variables with descriptive names? What about extracting complex conditions into well named function to understand what is going on (thus defeating the purpose of the "4 functions") ? This list could go on forever... Writing softwar…

But, "it is only as an aesthetic phenomenon that existence and the world are eternally justified." This piece of code can be viewed aesthetically. Artificial guidelines take the fun out of coding.

Re: C4 – C in 4 functions

#67

Post by diltonm »

petercooper wrote: post #3

I just wanted to credit Reddit's /r/tinycode sub-Reddit for this link: http://www.reddit.com/r/tinycode - it's a pretty cool place to discover minimalistic implementations of things.

Other than Minecraft I don't go to Reddit, this is a cool link though and one I'll be checking, thanks.

Re: C4 – C in 4 functions

#68

Post by ezy »

dabockster wrote: post #51
abecedarius wrote: post #23

On a first skim, this looks really nice; complaints that it's unreadable are unfounded. The background that makes it readable are Wirth's Compiler Construction http://www.ethoberon.ethz.ch/WirthPubl/CBEAll.pdf plus precedence climbing http://en.wikipedia.org/wiki/Operator-precedence_parser#Prec...

complaints that it's unreadable are unfounded Not exactly. You have to remember that language and compiler design require a LOT of work and experience to understand, and that many programmers will only see this as, frankly, spaghetti. I think it could have used some more block comments, but that's just me.

Well, the goal is for it to be minimal, and C doesn't actually do a lot of work for you. On reading it, the algorithm it uses to parse was of less interest than the various tricks it uses to initialize and manage the state of the parser in a compact way.

Re: C4 – C in 4 functions

#69

Post by abecedarius »

metaobject wrote: post #61
abecedarius wrote: post #54

Earlier quoted context omitted.

I'm writing a chapter for AOSA on something like this: a self-hosting compiler of a subset of Python to Python bytecode. It'll present the full code (about the same length) and try to explain it well for people not into compilers yet, but in the meantime I recommend the Wirth book. What's your favorite shorter intro? I'd especially like to reference other educational compilers that are self-hosting.

So, there is another version of Architecture of Open Source Applications in the works? I love the first two editions - they are unique books that really are gems. Are you able to divulge what projects are covered in the new version?

https://github.com/aosabook/500lines and I'm looking forward to reading it too. :)

I'm tempted to link to my draft chapter, but though the code is essentially done the text needs a lot of work.

Re: C4 – C in 4 functions

#70

Post by glibgil »

diltonm wrote: post #67
petercooper wrote: post #3

I just wanted to credit Reddit's /r/tinycode sub-Reddit for this link: http://www.reddit.com/r/tinycode - it's a pretty cool place to discover minimalistic implementations of things.

Other than Minecraft I don't go to Reddit, this is a cool link though and one I'll be checking, thanks.

Now you mostly go to reddit like anyone else. Is not going to reddit the new "I don't watch TV"?
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