Record instances

[kl0tl]

Are Semigroup, Monoid, Semiring and Ring instances for records using Record.Unsafe.unsafeSet on purpose instead of composing a bunch of record builders? Don’t that yield a lot more garbage?

Also is there a reason for not having records instances of Bounded, EuclideanRing and DivisionRing?

[natefaubion]

Not necessarily more garbage since builders will allocate closures (as opposed to new records). I think it's mainly that prelude doesn't depend on any other libraries, and Builder is part of purescript-record.

[hdgarrood]

There is a reason for not including EuclideanRing and DivisionRing: there’s no clear way of defining division when you have more than one field in the record. What should { a:1, b:2, c:3 } / { a:4, b:5, c:6 } be? Note that we can’t do { a: 1/4, b: 2/5; c: 3/6 } because that won’t satisfy the laws. In particular, division needs to be defined for any nonzero divisor, but if you have a zero in at least one field (but not all fields) you have an undefined result.

[hdgarrood]

I think a Bounded instance makes sense, given that we already give records Ord instances.

[kl0tl]

Thank you both for your answers 🙇 I added a Bounded instance for records in #208.