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Looks like a fun project, very nice :-) For those interested in more of the beautiful theory on extensible row types, this project seems to be based on an earl
by daanx 8y ago
Looks like a fun project, very nice :-)
For those interested in more of the beautiful theory on extensible row types, this project seems to be based on an earlier paper I wrote on scoped labels:
https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/scopedlabels.pdf https://www.microsoft.com/en-us/research/wp-content/uploads/...
- jimmyhmiller 8y agoThanks for the reference. Espresso doesn't support recursive records. Does system in your paper allow for those? Is there anything particularly tricky about supporting them?
- willtim 8y agoHi, author here, yes your paper was a huge inspiration and I really should add a references section in the readme. The row types in Expresso use very simple lacks constraints, similar to the old Hugs TREX system, and don't permit duplicate/scoped labels. I felt this was also a pretty good sweet spot.
- daanx 8y agoThanks :-) TREX (by Mark Jones and Benedict Gaster) is great. The beauty is that a lacks constraints can get translated to fields offsets at runtime making it super efficient! E.g. a type like: foo :: r/x => { x :: int | r } -> int foo r = r.x Gets translated at runtime to a function where the lacks constraint r/x becomes an actual offset parameter.