Sista putsande på Quantity! Åtminstone just nu...

Author: Oskar Lundström

Physics/src/Dimensions/Mole.png

@@ -17,6 +17,7 @@ Quantities
 >     ( Quantity
 >     , length, mass, time, current, temperature, substance, luminosity, one
 >     , velocity, acceleration, force, momentum
+>     , meter, kilogram, second, ampere, kelvin, mole, candela, unitless
 >     , (~=)
 >     , isZero
 >     , (#)
@@ -465,8 +466,6 @@ To solve these two problems we'll introduce some syntactic sugar. First some pre
 
 And now the sugar.
 
-TODO: Please multiply the values instead of throwing them away. I'm pretty sure (#) should behave as "scale" of a vector space. So that (x#(y#z)) == ((x*y)#z).
-
 > (#) :: (Num v) => v -> Quantity d v -> Quantity d v
 > v # (ValQuantity d bv) = ValQuantity d (v*bv)
 
@@ -490,6 +489,8 @@ But let's not stop there. It would be prettier if you could actually write `mete
 
 **Exercise** Make it so that one can write the SI-units instead of the base dimensions when one uses the sugar. Then show how to write $4$ seconds.
 
+![](Mole.png "A different kind of mole..."){.float-img-right}
+
 <details>
 <summary>**Solution**</summary>
 <div>
@@ -501,7 +502,7 @@ But let's not stop there. It would be prettier if you could actually write `mete
 > kelvin   = temperature
 > mole     = substance
 > candela  = luminosity
-> unitless = 
+> unitless = one
 
 > fourSeconds = 4 # second
 

Physics/src/Dimensions/Quantity.lhs

@@ -2,6 +2,8 @@
 Testing of Quantity
 ===================
 
+\ignore{
+
 > {-# LANGUAGE DataKinds #-}
 > {-# LANGUAGE GADTs #-}
 > {-# LANGUAGE KindSignatures #-}
@@ -11,11 +13,23 @@ Testing of Quantity
 > {-# LANGUAGE FlexibleInstances #-}
 > {-# LANGUAGE TypeSynonymInstances #-}
 
+}
+
 > module Dimensions.Quantity.Test
 > ( runTests
 > )
 > where
 
+
+< {-# LANGUAGE DataKinds #-}
+< {-# LANGUAGE GADTs #-}
+< {-# LANGUAGE KindSignatures #-}
+< {-# LANGUAGE TypeFamilies #-}
+< {-# LANGUAGE UndecidableInstances #-}
+< {-# LANGUAGE TypeOperators #-}
+< {-# LANGUAGE FlexibleInstances #-}
+< {-# LANGUAGE TypeSynonymInstances #-}
+
 > import Prelude hiding (length, div)
 > import Test.QuickCheck
 
@@ -36,9 +50,9 @@ First we need an `Arbitrary` instance for `Quantity d val`. For `d` we'll mostly
 A generator for an arbitrary dimension.
 
 > genQuantity :: Quantity d Double -> Gen (Q d)
-> genQuantity sugar = do
+> genQuantity quantity = do
 >   value <- arbitrary
->   return (value # sugar)
+>   return (value # quantity)
 
 And now we make `Arbitrary` instances of arbitrary selected dimensions in the `Quantity`s.
 
@@ -57,7 +71,7 @@ And now we make `Arbitrary` instances of arbitrary selected dimensions in the `Q
 Testing arithmetic properties
 -----------------------------
 
-One regular numbers, and hence too on quantites with their dimensions, a bunch of properties should hold. The things we test here are
+On regular numbers, and hence too on quantites with their dimensions, a bunch of properties should hold. The things we test here are
 
 - Addition commutative
 - Addition associative
@@ -69,20 +83,14 @@ One regular numbers, and hence too on quantites with their dimensions, a bunch o
 - Subtraction and addition cancel each other out
 - Division and multiplication cancel each other out
 - Pythagoran trigonometric identity
-- The sugar doesn't care about input value
 
 Let's start!
 
 We could write the type signatures in a general way like
 
 < prop_addCom :: Q d -> Q d -> Bool
 
-But we won't do that for two reasons.
-
-1. QuickCheck needs concrete types in order to work. So we would have to do a bunch of specialization anyway. And even if we begin with a general signature, we can't cover all cases since there are infinitly many dimensions.
-2. TODO: Går inte för vissa fall, t.ex. 
-
-< Couldn't match type `Mul d (Mul d d)' with `Mul (Mul d d) d'
+But we won't do that since QuickCheck needs concrete types in order to work. So we would have to do a bunch of specialization anyway. And even if we begin with a general signature, we can't cover all cases since there are infinitly many dimensions.
 
 Instead we'll pick some arbitrary dimensions that have an `Arbitrary` instance.
 
@@ -98,7 +106,6 @@ Instead we'll pick some arbitrary dimensions that have an `Arbitrary` instance.
 > prop_addId :: Q Time -> Bool
 > prop_addId a = zero +# a ~= a
 >   where
->     -- `zero` will, thanks to the versatile suger, have >     -- the same dimension as `a`.
 >     zero = 0 # a
 
 > -- a * b = b * a
@@ -133,33 +140,24 @@ Instead we'll pick some arbitrary dimensions that have an `Arbitrary` instance.
 > prop_pythagoranIdentity a = sinq a *# sinq a +#
 >                             cosq a *# cosq a ~= (1 # one)
 
-> prop_sugar :: Double -> Q Length -> Q Length -> Bool
-> prop_sugar v a b = v # a ~= v # b
+
+\ignore{
 
 Integrating tests with Stack
 ----------------------------
 
 > runTests :: IO ()
 > runTests = do
->   putStrLn "Dimensions quantity: Addition commutative"
 >   quickCheck prop_addCom
->   putStrLn "Dimensions quantity: Addition associative"
 >   quickCheck prop_addAss
->   putStrLn "Dimensions quantity: Zero is identity for addition"
 >   quickCheck prop_addId
->   putStrLn "Dimensions quantity: Multiplication commutative"
 >   quickCheck prop_mulCom
->   putStrLn "Dimensions quantity: Multiplication associative"
 >   quickCheck prop_mulAss
->   putStrLn "Dimensions quantity: One is identity for multiplication"
 >   quickCheck prop_mulId
->   putStrLn "Dimensions quantity: Addition distributes over multiplication"
 >   quickCheck prop_addDistOverMul
->   putStrLn "Dimensions quantity: Subtraction and addition cancel each other out"
 >   quickCheck prop_addSubCancel
->   putStrLn "Dimensions quantity: Division and multiplication cancel each other out"
 >   quickCheck prop_mulDivCancel
->   putStrLn "Dimensions quantity: Pythagoran trigonometric identity"
 >   quickCheck prop_pythagoranIdentity
->   putStrLn "Dimensions quantity: Sugar is correct"
->   quickCheck prop_sugar
+>   putStrLn "Dimensions Quantity tests passed!"
+
+}

Physics/src/Dimensions/Quantity/Test.lhs

@@ -2,16 +2,22 @@
 Usage
 =====
 
-In this module we'll show how to use value-level dimensions, type-level dimensions and `Quantity` in an "actual" progam.
+\ignore{
 
 > {-# LANGUAGE TypeOperators #-}
 
+}
+
 > module Dimensions.Usage
 > (
 > )
 > where
 
-Let's first import the things we have created.
+In this module we'll show how to use value-level dimensions, type-level dimensions and `Quantity` in an "actual" progam. Let's first use this fancy GHC-extension
+
+< {-# LANGUAGE TypeOperators #-}
+
+and then import the things we have created.
 
 > import Dimensions.TypeLevel
 > import Dimensions.Quantity
@@ -24,8 +30,6 @@ Values and types
 
 Let's create a length, time and mass, in the way hinted in the previous chapter.
 
-TODO: Av okända skäl så blir de nedanstående av typ `Integer` om ej en decimal tas med. Man vill nog ha dom som `Double`. Idealt skulle de ha typ `(Num v) => v` men jag har inte fått till det så bra.
-
 < myLength = 10.0 # length
 < myTime   = 20.0 # time
 < myMass   = 30.0 # mass