dotnet · BillWagner · Apr 11, 2022 · Apr 9, 2022
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+module equals1
+
+// <Snippet1>
+open System
+
+let scores = 
+    [| Tuple<string, Nullable<int>>("Dan", 90)
+       Tuple<string, Nullable<int>>("Ernie", Nullable())
+       Tuple<string, Nullable<int>>("Jill", 88)
+       Tuple<string, Nullable<int>>("Ernie", Nullable()) 
+       Tuple<string, Nullable<int>>("Nancy", 88)
+       Tuple<string, Nullable<int>>("Dan", 90) |]
+
+// Compare the Tuple objects
+for ctr = 0 to scores.Length - 1 do
+    for innerCtr = ctr + 1 to scores.Length - 1 do
+        printfn $"{scores[ctr]} = {scores[innerCtr]}: {scores[ctr].Equals scores[innerCtr]}"
+    printfn ""
+// The example displays the following output:
+//       (Dan, 90) = (Ernie, ): False
+//       (Dan, 90) = (Jill, 88): False
+//       (Dan, 90) = (Ernie, ): False
+//       (Dan, 90) = (Nancy, 88): False
+//       (Dan, 90) = (Dan, 90): True
+//       
+//       (Ernie, ) = (Jill, 88): False
+//       (Ernie, ) = (Ernie, ): True
+//       (Ernie, ) = (Nancy, 88): False
+//       (Ernie, ) = (Dan, 90): False
+//       
+//       (Jill, 88) = (Ernie, ): False
+//       (Jill, 88) = (Nancy, 88): False
+//       (Jill, 88) = (Dan, 90): False
+//       
+//       (Ernie, ) = (Nancy, 88): False
+//       (Ernie, ) = (Dan, 90): False
+//       
+//       (Nancy, 88) = (Dan, 90): False
+// </Snippet1>
@@ -0,0 +1,50 @@
+module equals2
+
+// <Snippet2>
+open System
+open System.Collections
+
+type Item2Comparer<'T1, 'T2 when 'T1: equality and 'T2: equality>() = 
+    interface IEqualityComparer with    
+        member _.GetHashCode(obj) =
+            match obj with
+            | :? 'T1 as obj->
+                obj.GetHashCode()
+            | _ ->
+                (obj :?> 'T2).GetHashCode()
+
+        member _.Equals(x, y) =
+            // Return true for all values of Item1.
+            match x with
+            | :? 'T1 ->
+                true
+            | _ ->
+                x.Equals y
+
+let distancesWalked =
+    [| Tuple.Create("Jan", Double.NaN) 
+       Tuple.Create("Joe", Double.NaN) 
+       Tuple.Create("Adam", 1.36)
+       Tuple.Create("Selena", 2.01)
+       Tuple.Create("Jake", 1.36) |]
+
+for ctr = 0 to distancesWalked.Length - 1 do
+    let distanceWalked = distancesWalked[ctr]
+    for ctr2 = ctr + 1 to distancesWalked.Length - 1 do
+        printfn $"{distanceWalked} = {distancesWalked[ctr2]}: {(distanceWalked :> IStructuralEquatable).Equals(distancesWalked[ctr2], Item2Comparer<string, double>())}"
+    printfn ""
+// The example displays the following output:
+//       (Jan, NaN) = (Joe, NaN): True
+//       (Jan, NaN) = (Adam, 1.36): False
+//       (Jan, NaN) = (Selena, 2.01): False
+//       (Jan, NaN) = (Jake, 1.36): False
+//       
+//       (Joe, NaN) = (Adam, 1.36): False
+//       (Joe, NaN) = (Selena, 2.01): False
+//       (Joe, NaN) = (Jake, 1.36): False
+//       
+//       (Adam, 1.36) = (Selena, 2.01): False
+//       (Adam, 1.36) = (Jake, 1.36): True
+//       
+//       (Selena, 2.01) = (Jake, 1.36): False
+// </Snippet2>
@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="equals1.fs" />
+    <Compile Include="equals2.fs" />
+  </ItemGroup>
+</Project>
@@ -0,0 +1,33 @@
+module example1
+
+// <Snippet1>
+open System
+
+let scores = 
+    [| Tuple<string, Nullable<int>>("Jack", 78)
+       Tuple<string, Nullable<int>>("Abbey", 92) 
+       Tuple<string, Nullable<int>>("Dave", 88)
+       Tuple<string, Nullable<int>>("Sam", 91) 
+       Tuple<string, Nullable<int>>("Ed", Nullable())
+       Tuple<string, Nullable<int>>("Penelope", 82)
+       Tuple<string, Nullable<int>>("Linda", 99)
+       Tuple<string, Nullable<int>>("Judith", 84) |]
+
+let computeMean (scores: Tuple<string, Nullable<int>>[]) (n: int outref) = 
+    n <- 0      
+    let mutable sum = 0
+    for _, score in scores do
+        if score.HasValue then
+            n <- n + 1
+            sum <- sum + score.Value
+    if n > 0 then
+        double sum / double n
+    else
+        0
+
+let mutable number = 0
+let mean = computeMean scores &number
+printfn $"Average test score: {mean:N2} (n={number})"
+// The example displays the following output:
+//       Average test score: 87.71 (n=7)
+// </Snippet1>
@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="example1.fs" />
+    <Compile Include="item1.fs" />
+  </ItemGroup>
+</Project>
@@ -0,0 +1,34 @@
+module item1
+
+// <Snippet1>
+open System
+
+let integerDivide (dividend: int) divisor =
+    try
+        let quotient, remainder = Math.DivRem(dividend, divisor)
+        Tuple<int, int>(quotient, remainder)
+    with :? DivideByZeroException ->
+        Unchecked.defaultof<Tuple<int, int>>
+
+[<EntryPoint>]
+let main _ =
+    let dividend = 136945 
+    let divisor = 178
+    let result = integerDivide dividend divisor
+    if box result <> null then
+        printfn $@"{dividend} \ {divisor} = {result.Item1}, remainder {result.Item2}" 
+    else
+        printfn $@"{dividend} \ {divisor} = <Error>"
+
+    let dividend = Int32.MaxValue 
+    let divisor = -2073
+    let result = integerDivide dividend divisor
+    if box result <> null then
+        printfn $@"{dividend} \ {divisor} = {result.Item1}, remainder {result.Item2}" 
+    else
+        printfn $@"{dividend} \ {divisor} = <Error>"
+    0
+// The example displays the following output:
+//       136945 \ 178 = 769, remainder 63
+//       2147483647 \ -2073 = -1035930, remainder 757
+// </Snippet1>
@@ -0,0 +1,47 @@
+module compareto1
+
+// <Snippet1>
+open System
+
+let scores = 
+    [| Tuple<string, Nullable<int>>("Jack", 78)
+       Tuple<string, Nullable<int>>("Abbey", 92) 
+       Tuple<string, Nullable<int>>("Dave", 88)
+       Tuple<string, Nullable<int>>("Sam", 91) 
+       Tuple<string, Nullable<int>>("Ed", Nullable())
+       Tuple<string, Nullable<int>>("Penelope", 82)
+       Tuple<string, Nullable<int>>("Linda", 99)
+       Tuple<string, Nullable<int>>("Judith", 84) |]
+
+printfn "The values in unsorted order:"
+for score in scores do
+    printfn $"{score}"
+
+printfn ""
+
+Array.Sort scores
+
+printfn "The values in sorted order:"
+for score in scores do
+    printfn $"{score}"
+// The example displays the following output
+//       The values in unsorted order:
+//       (Jack, 78)
+//       (Abbey, 92)
+//       (Dave, 88)
+//       (Sam, 91)
+//       (Ed, )
+//       (Penelope, 82)
+//       (Linda, 99)
+//       (Judith, 84)
+//       
+//       The values in sorted order:
+//       (Abbey, 92)
+//       (Dave, 88)
+//       (Ed, )
+//       (Jack, 78)
+//       (Judith, 84)
+//       (Linda, 99)
+//       (Penelope, 82)
+//       (Sam, 91)
+// </Snippet1>
@@ -0,0 +1,58 @@
+module compareto2
+
+// <Snippet2>
+open System
+open System.Collections
+open System.Collections.Generic
+
+type ScoreComparer<'T1, 'T2>() =
+    interface IComparer with
+        member _.Compare(x: obj, y: obj) =
+            match x with
+            | :? Tuple<'T1, 'T2> as tX ->
+                let tY = y :?> Tuple<'T1, 'T2>
+                Comparer<'T2>.Default.Compare(tX.Item2, tY.Item2)             
+            | _ -> 0
+
+let scores = 
+    [| Tuple<string, Nullable<int>>("Jack", 78)
+       Tuple<string, Nullable<int>>("Abbey", 92) 
+       Tuple<string, Nullable<int>>("Dave", 88)
+       Tuple<string, Nullable<int>>("Sam", 91) 
+       Tuple<string, Nullable<int>>("Ed", Nullable())
+       Tuple<string, Nullable<int>>("Penelope", 82)
+       Tuple<string, Nullable<int>>("Linda", 99)
+       Tuple<string, Nullable<int>>("Judith", 84) |]
+
+printfn "The values in unsorted order:"
+for score in scores do
+    printfn $"{score}"
+
+printfn ""
+
+Array.Sort(scores, ScoreComparer<string, Nullable<int>>())
+
+printfn "The values in sorted order:"
+for score in scores do
+    printfn $"{score}"
+// The example displays the following output
+//       The values in unsorted order:
+//       (Jack, 78)
+//       (Abbey, 92)
+//       (Dave, 88)
+//       (Sam, 91)
+//       (Ed, )
+//       (Penelope, 82)
+//       (Linda, 99)
+//       (Judith, 84)
+//       
+//       The values in sorted order:
+//       (Ed, )
+//       (Jack, 78)
+//       (Penelope, 82)
+//       (Judith, 84)
+//       (Dave, 88)
+//       (Sam, 91)
+//       (Abbey, 92)
+//       (Linda, 99)
+// </Snippet2>
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="compareto1.fs" />
+    <Compile Include="compareto2.fs" />
+  </ItemGroup>
+</Project>
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="tostring1.fs" />
+  </ItemGroup>
+</Project>
@@ -0,0 +1,24 @@
+//<Snippet1>
+open System
+
+let scores = 
+    [| Tuple<string, Nullable<int>>("Abbey", 92) 
+       Tuple<string, Nullable<int>>("Dave", 88)
+       Tuple<string, Nullable<int>>("Ed", Nullable())
+       Tuple<string, Nullable<int>>("Jack", 78)
+       Tuple<string, Nullable<int>>("Linda", 99)
+       Tuple<string, Nullable<int>>("Judith", 84)
+       Tuple<string, Nullable<int>>("Penelope", 82)
+       Tuple<string, Nullable<int>>("Sam", 91) |]
+for score in scores do
+    printfn $"{score.ToString()}"
+// The example displays the following output:
+//       (Abbey, 92)
+//       (Dave, 88)
+//       (Ed, )
+//       (Jack, 78)
+//       (Linda, 99)
+//       (Judith, 84)
+//       (Penelope, 82)
+//       (Sam, 91)
+// </Snippet1>