1. Macho: Programming With Man Pages Anthony Cozzie, Murph Finnicum, Sam King University of Illinois at Urbana-Champaign

2. Programming is hard! Extreme Detail Extreme Precision

3. Lots of Automated Tools Static Analysis – Coverity Code Snippet search engines – Prospector, SNIFF, Xsnippet, even Google Automated Debuggers – Genetic programming, Delta debugging

4. Automating Programming Computer makes decisions But it will make mistakes too! Programmer must go back and check the tool – not easy So, how can we do this efficiently?

5. Macho Architecture NL parsing Database Stitching Debugger Raw Text Requested Computation Code Snippets Candidate Programs Runtime Feedback Solutions

6. The Trick NL parsing Database Stitching Debugger

7. Examples! Example is end-to-end: covers many decisions Easy to understand compared to code

8. The Example (LS) Print the names of files in a directory. Sort the names.

9. Extract Implied Computation directory -> files files -> names print(names) sort(names) Print the names of files in a directory. Sort names.

10. Use Programmer’s Labels public static void main(String[] args) {.... //first (original) database files = directory.listFiles();.... }

12. Input to Synthesis: LS1 public static void Ls1(java.lang.String p_directory) { java.io.File tmp = new File(p_directory); java.io.File[] files = tmp.listFiles(); int tmp_0 = files.length; java.lang.String[] tmp_1 = new java.lang.String[tmp_0]; for(int tmp_3 = 0; tmp_3 < files.length; ++tmp_3) { java.io.File tmp_2 = files[tmp_3]; java.lang.String names = tmp_2.getName(); tmp_1[tmp_3] = names; } Arrays.sort(tmp_1); for(int tmp_5 = 0; tmp_5 < tmp_1.length; ++tmp_5) { java.lang.String tmp_4 = tmp_1[tmp_5]; System.out.println(tmp_4); }

13. Bugs! Prints hidden files Crashes if the input is not a directory

15. Synthesized Version of LS public static void Ls3(String p_dir) { java.io.File tmp = new File(p_dir); java.io.File[] files = tmp.listFiles(); boolean tmp_3 = tmp.isDirectory(); if(tmp_3) { Arrays.sort(files); for(int tmp_1 = 0; tmp_1 < files.length; ++tmp_1) { java.io.File tmp_0 = files[tmp_1]; java.lang.String names = tmp_0.getName(); boolean tmp_2 = tmp_0.isHidden(); if(!tmp_2) System.out.println(names); } else System.out.println(tmp + ""); }

16. Pure NL Spec Take the path "/home/zerocool/" If the path is a file, print it. Otherwise get the list of files in the directory. Sort the result alphabetically. Go over the result from the beginning to the end: If the current element's filename does not begin with ".", print it.

17. Macho Print the names of files in a directory. Sort the names. + simple example

18. Input Synergy NL: moderate information over a large part of the state space Examples: very precise information over a tiny part of the state space Together: win