hack on

from WordNet (r) 3.0 (2006)

hack on
    v 1: fix a computer program piecemeal until it works; "I'm not
         very good at hacking but I'll give it my best" [syn:
         {hack}, {hack on}]

from Jargon File (4.4.4, 14 Aug 2003)

hack on
 vt.

   [very common] To {hack}; implies that the subject is some pre-existing
   hunk of code that one is evolving, as opposed to something one might
   {hack up}.

from The Free On-line Dictionary of Computing (8 July 2008)

hack on

   To {hack}; implies that the subject is some pre-existing hunk
   of code that one is evolving, as opposed to something one
   might {hack up}.

   [{Jargon File}]

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