What's the (short) type of `10 *~ (watt / second)`

Question

Quick question: Using dimensional GHC infers the type of testRate = 10 *~ (watt / second) to be:

testRate
  :: Numeric.Units.Dimensional.Quantity
       (Numeric.Units.Dimensional.Dim
          (numtype-1.0.1:Numeric.NumType.Pos
             numtype-1.0.1:Numeric.NumType.Pos1)
          (numtype-1.0.1:Numeric.NumType.Pos
             numtype-1.0.1:Numeric.NumType.Zero)
          (numtype-1.0.1:Numeric.NumType.Neg
             (numtype-1.0.1:Numeric.NumType.Neg
                numtype-1.0.1:Numeric.NumType.Neg2))
          numtype-1.0.1:Numeric.NumType.Zero
          numtype-1.0.1:Numeric.NumType.Zero
          numtype-1.0.1:Numeric.NumType.Zero
          numtype-1.0.1:Numeric.NumType.Zero)
       a

What would be the short type of testRate? And how do I derive the type of other such units?

Sjoerd Visscher · Accepted Answer · 2013-12-13T14:16:36.393

3

If you switch to dimensional-tf you can write it as

testRate :: Quantity (Div DPower DTime) a

I don't think there's a good generic way to derive these types, just write down the type equivalent of what you think the unit should be (using Mul and Div).

edited Dec 13 '13 at 14:16

answered Dec 13 '13 at 14:08

Sjoerd Visscher

11,840
2
47
59

score 0 · Answer 2 · answered Dec 13 '13 at 13:47

0

What do you mean by the short type? The best you could do would be to remove all the module qualifiers, eg

testRate
  :: Quantity
       (Dim
          (Pos Pos1)
          (Pos Zero)
          (Neg (Neg Neg2))
          Zero
          Zero
          Zero
          Zero)
       a

answered Dec 13 '13 at 13:47

Chris Taylor

46,912
15
110
154

By "short" I mean something that makes obvious that we are dealing with `power over time` here. I could of course define `type powerOverTime :: Quantity (Dim ...` but I hope there is a better way. – fho Dec 13 '13 at 13:58

What's the (short) type of `10 *~ (watt / second)`

2 Answers2