Implicitly chain conversion factors #50
Description
Given an implicit ConversionFactor[P, Q, A, B] and a ConversionFactor[P, Q, B, C], create a ConversionFactor[P, Q, A, C].
Where there are multiple units for a single dimension, conversion factors need to be defined between each pair individually. This means that there's a matrix of implicit conversion factors that need to be written. E.g. for degree, arcsecond and arcminute, conversion factors need to be written for arcsecond - arcminute, arcminute - degree and arcsecond - degree.
It should technically be possible to implicitly derive the arcsecond - degree conversion using the previous two. This would remove a lot of boilerplate when adding new units.
The following implicit fails to resolve:
implicit def failedAttemptAtChaining[P, Q, A, B](implicit ab: ConversionFactor[P, Q, A, B], bc: ConversionFactor[P, Q, B, C]): ConversionFactor[P, Q, A, C] = ???This is probably because the compiler cannot resolve B, as it only knows A and C.