Add Molarity module

See ianmackenzie#6.

An SI unit, mole per cubic meter (mol/m3), `Molarity` is an amount of
substance divided by the volume of the mixture. Values stored in number
of mole per cubic meter. All `*PerLiter` definitions are defined in
terms of `decimolesPerLiter`. Why? This was done because a liter equal
to a cubic decimeter, and `mole per cubic meter` is a `Rate`. This may
make the various `*PerLiter` definition appear off by a factor of 10
because the definitions are in terms of decimoles per cubic decimeter
(same as `decimolesPerLiter`).

elm.json

@@ -24,6 +24,7 @@
         "LuminousFlux",
         "LuminousIntensity",
         "Mass",
+        "Molarity",
         "Pixels",
         "Power",
         "Pressure",

src/Molarity.elm

@@ -0,0 +1,110 @@
+module Molarity exposing
+    ( Molarity, MolesPerCubicMeter
+    , molesPerCubicMeter, inMolesPerCubicMeter
+    , decimolesPerLiter, inDecimolesPerLiter
+    , centimolesPerLiter, inCentimolesPerLiter
+    , millimolesPerLiter, inMillimolesPerLiter
+    , micromolesPerLiter, inMicromolesPerLiter
+    )
+
+{-| A `Molarity` value represents a concentration in mole per cubic meter, decimoles per liter, etc.
+It is stored in number of mole per cubic meter.
+
+An SI unit, mole per cubic meter (mol/m3), `Molarity` is an amount of substance divided by the volume of the mixture.
+
+_Note: A liter is equal to a cubic decimeter._
+
+Section 8.6.5 in Chapter 8 of the [NIST Guide to the SI](https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-8) does notes that the term molarity is consider obsolete. The initial decision to use `Molarity` as the module name was due to the verbosity of "amount-of-substance concentration".
+
+@docs Molarity, MolesPerCubicMeter
+@docs molesPerCubicMeter, inMolesPerCubicMeter
+@docs decimolesPerLiter, inDecimolesPerLiter
+@docs centimolesPerLiter, inCentimolesPerLiter
+@docs millimolesPerLiter, inMillimolesPerLiter
+@docs micromolesPerLiter, inMicromolesPerLiter
+
+-}
+
+import Quantity exposing (Quantity(..), Rate)
+import SubstanceAmount exposing (Moles)
+import Volume exposing (CubicMeters)
+
+
+{-| -}
+type alias MolesPerCubicMeter =
+    Rate Moles CubicMeters
+
+
+{-| -}
+type alias Molarity =
+    Quantity Float MolesPerCubicMeter
+
+
+{-| Construct a molarity from a number of moles per cubic meter.
+-}
+molesPerCubicMeter : Float -> Molarity
+molesPerCubicMeter numMolesPerCubicMeter =
+    Quantity numMolesPerCubicMeter
+
+
+{-| Convert a molarity to a number of moles per cubic meter.
+-}
+inMolesPerCubicMeter : Molarity -> Float
+inMolesPerCubicMeter (Quantity numMolesPerCubicMeter) =
+    numMolesPerCubicMeter
+
+
+{-| Construct a molarity from a number of decimoles per liter.
+-}
+decimolesPerLiter : Float -> Molarity
+decimolesPerLiter numDecimolesPerLiter =
+    molesPerCubicMeter (10 * numDecimolesPerLiter)
+
+
+{-| Convert a molarity to a number of decimoles per liter.
+-}
+inDecimolesPerLiter : Molarity -> Float
+inDecimolesPerLiter (Quantity numMolesPerCubicMeter) =
+    numMolesPerCubicMeter / 10
+
+
+{-| Construct a molarity from a number of centimoles per liter.
+-}
+centimolesPerLiter : Float -> Molarity
+centimolesPerLiter numCentimolesPerLiter =
+    decimolesPerLiter (10 * numCentimolesPerLiter)
+
+
+{-| Convert a molarity to a number of centimoles per liter.
+-}
+inCentimolesPerLiter : Molarity -> Float
+inCentimolesPerLiter molar =
+    inDecimolesPerLiter molar / 10
+
+
+{-| Construct a molarity from a number of millimoles per liter.
+-}
+millimolesPerLiter : Float -> Molarity
+millimolesPerLiter numMillimolesPerLiter =
+    decimolesPerLiter (100 * numMillimolesPerLiter)
+
+
+{-| Convert a molarity to a number of millimoles per liter.
+-}
+inMillimolesPerLiter : Molarity -> Float
+inMillimolesPerLiter molar =
+    inDecimolesPerLiter molar / 100
+
+
+{-| Construct a molarity from a number of micromoles per liter.
+-}
+micromolesPerLiter : Float -> Molarity
+micromolesPerLiter numMicromolesPerLiter =
+    decimolesPerLiter (1000 * numMicromolesPerLiter)
+
+
+{-| Convert a molarity to a number of micromoles per liter.
+-}
+inMicromolesPerLiter : Molarity -> Float
+inMicromolesPerLiter molar =
+    inDecimolesPerLiter molar / 1000

tests/Tests.elm

@@ -46,6 +46,7 @@ import Luminance
 import LuminousFlux
 import LuminousIntensity
 import Mass exposing (..)
+import Molarity exposing (..)
 import Pixels exposing (..)
 import Power exposing (..)
 import Pressure exposing (..)
@@ -525,6 +526,13 @@ conversionsToQuantityAndBack =
             , fuzzFloatToQuantityAndBack "shortTons" Mass.shortTons Mass.inShortTons
             , fuzzFloatToQuantityAndBack "longTons" Mass.longTons Mass.inLongTons
             ]
+        , Test.describe "Molarity" <|
+            [ fuzzFloatToQuantityAndBack "molesPerCubicMeter" Molarity.molesPerCubicMeter Molarity.inMolesPerCubicMeter
+            , fuzzFloatToQuantityAndBack "decimolesPerLiter" Molarity.decimolesPerLiter Molarity.inDecimolesPerLiter
+            , fuzzFloatToQuantityAndBack "centimolesPerLiter" Molarity.centimolesPerLiter Molarity.inCentimolesPerLiter
+            , fuzzFloatToQuantityAndBack "millimolesPerLiter" Molarity.millimolesPerLiter Molarity.inMillimolesPerLiter
+            , fuzzFloatToQuantityAndBack "micromolesPerLiter" Molarity.micromolesPerLiter Molarity.inMicromolesPerLiter
+            ]
         , Test.describe "Pixels" <|
             [ fuzzFloatToQuantityAndBack "pixels" Pixels.pixels Pixels.inPixels
             , fuzzFloatToQuantityAndBack "pixelsPerSecond" Pixels.pixelsPerSecond Pixels.inPixelsPerSecond