Swi-Prolog Projects for porting to YAP Prolog

In a Nutshell, Swi-Prolog Projects for porting to YA...

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  has had 8,482 commits made by 41 contributors
  representing 363,007 lines of code
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  is mostly written in Prolog
  with a well-commented source code
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  has a well established, mature codebase
  maintained by nobody
  with stable Y-O-Y commits
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  took an estimated 95 years of effort (COCOMO model)
  starting with its first commit in March, 2000
  ending with its most recent commit almost 4 years ago