The ParaSail core is under the GPLv3, but the ParaSail stdlib is in public domain. A citation of Tucker Taft from 

https://groups.google.com/forum/#!topic/parasail-programming-language/EtT-l4BvUbo

https://archive.is/qFoTG (the quote can be seen by clicking on the text of one of the visible comments and then by scrolling downwards with arrow keys)

Actually there is no GPL copyright notice on the ParaSail standard 

library.  I'll see what words need to be added to the copyright notice 

to make it clearer that the ParaSail standard library can be freely re-used. 

The issue got raised again on 2019_06_30, but it didn't receive a thorough answer.