Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Show HN: XKCD-inspired StackSort

gkoberger.github.com

Post reply on HN
Print view View original

131–140 of 210 posts

Re: Show HN: XKCD-inspired StackSort

#131

Post by gridspy »

milkshakes wrote: post #72

This reminds me of a project I was exposed to at school[1] It allows you to search for code by the test cases it passes. It was a little slow, but that was one of the first times computers truly felt magical to me. [1] http://cs.brown.edu/~spr/research/s6.html

That is truly awesome! Thanks for sharing.

Quote from the linked article:

"

The system works by using the keywords to access one of the available code search engines (or a local code search engine for code available at Brown), to get candidate files. Each class or method in these files (depending on what the user is searching for) is considered a potential solution. These solutions are then transformed using a set of about 30 transformations in an attempt to map the code into exactly what the programmer specified. The transformations range from the simple (e.g. changing the name of the method to match the signature) to the complex (e.g. finding a line in the method that computes a value of the returned type and then doing a backward slice until the only free variables are values of the parameter types). All the solutions that can be transformed to match the signature are then tested using the given test cases, security constraints, and JML rules.

"

Re: Show HN: XKCD-inspired StackSort

#134

Post by piyush_soni »

gkoberger wrote: post #132
piyush_soni wrote: post #115

Humm ... 6 minutes already, but it's still "Fetching page 1..." for me.

Some people have reported that its doing this for some Firefox configurations. Try Chrome?

Humm ... works instantly with Chrome. Not sure why it's not working with Firefox (haven't seen the code yet - might debug if I get some time)

Re: Show HN: XKCD-inspired StackSort

#135

Post by RodgerTheGreat »

fizx wrote: post #113
RodgerTheGreat wrote: post #107

Earlier quoted context omitted.

Forth, Factor, APL or any other concatenative language provides the benefit of a "point free" style in which there are no explicitly named variables- that's one way to reduce the possibility space of programs. In the case of Factor (or Forth with an appropriate DSL) you could further use type information to ensure that your program generator only used words in sequence whose stack effects match up properly- ie a 'val…

Perhaps worth noting: java bytecode is a concatenative language. There are probably more commercially interesting java corpora than forth corpora. If you want to get paid to play around with this thought, my contact info is in my HN profile.

Java bytecode is stack-based, but it isn't really concatenative. The term "concatenative" refers to how code fragments can be composed via concatenation. This means that simple textual substitution is sufficient for inlining code or breaking code into functions. For example, consider a Forth word which determines whether a number is divisible by three or five:

  : fizzbuzzable  dup 3 mod 0= swap 5 mod 0= or ;
There's a repeated pattern here, so we can textually excise it and make it into a named word without changing any of the structure of the surrounding program:

  : /?            mod 0=                ;
  : fizzbuzzable  dup 3 /? swap 5 /? or ;
Or we could break it down a different way by excising different fragments:

  : /3?           3 mod 0=            ;
  : /5?           5 mod 0=            ;
  : fizzbuzzable  dup /3? swap /5? or ;
(Obviously not the best real-world example, but hopefully it illustrates the idea.)

Java bytecode, on the other hand, uses local variable references and activation records. This means that inlining or breaking out a procedure has pretty much the same problems as inlining or breaking out a procedure manually in C- variable names may clash, new arguments have to be threaded around, parts of expressions may need to be stored in temporary variables, etc. the JVM additionally enforces many constraints on "well-formed" bytecode at class load time[1] which could make it hard to generate valid programs by chance. Overall, Trying to "harvest" java bytecode from the wild could be useful, but I think that would be much harder than it sounds at first.

[1] http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.htm... (and below)

Re: Show HN: XKCD-inspired StackSort

#137

Post by vanderZwan »

bo1024 wrote: post #108
recuter wrote: post #5

If you give it about 30 seconds it works eventually, this is beautiful. I had a good laugh. Edit: It makes me want to do something crazy like setup a tool chain that cobbles whole programs together with trial and error like this. Throw enough resources at it maybe it will be faster and cheaper than your avg. developer. It will be an unmaintainable mess as if you used Brainfuck or Perl. But it will run, by god, it wil…

The key last step is to have it automatically post questions to StackOverflow to fill in the last code snippets it can't complete.

"And that, Neo, is how computers became self-aware and learned to exploit human brain-cycles, eventually resulting in the Matrix."
Post reply on HN