sritchie commented 5 years ago

This PR adds a contramap implementation; this lets me get instances of ToReal[B] for types where I can extract something numeric, say, but for which I can't actually define a Numeric[B] instance.

I'm using this with algebird's AveragedValue. I'd like to be able to have the ToReal implicit handle the conversion rather than explicitly taking a function from T => Double, in this case. With this PR I can write:

  implicit val avToReal: ToReal[AveragedValue] =
    implicitly[ToReal[Double]].contramap(_.value)

codecov-io commented 5 years ago

Codecov Report

Merging #377 into develop will increase coverage by 0.03%. The diff coverage is 0%.

@@             Coverage Diff             @@
##           develop     #377      +/-   ##
===========================================
+ Coverage    45.84%   45.87%   +0.03%     
===========================================
  Files           86       86              
  Lines         3067     3069       +2     
  Branches       141      135       -6     
===========================================
+ Hits          1406     1408       +2     
  Misses        1661     1661

Impacted Files	Coverage Δ
...main/scala/com/stripe/rainier/compute/ToReal.scala	`73.33% <0%> (-11.29%)`	:arrow_down:
...ain/scala/com/stripe/rainier/compute/RealOps.scala	`78.81% <0%> (+1.69%)`	:arrow_up:

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avibryant commented 5 years ago

LGTM

stripe / rainier

add contramap implementation to ToReal #377

Codecov Report