Replaced Result<T> with normal TryXXX pattern.

src/Hl7.Fhir.Base/ElementModel/Types/Any.cs

@@ -154,7 +154,7 @@ public static bool TryConvert(object? value, [NotNullWhen(true)] out Any? primit
     }
 
     // some utility methods shared by the subclasses
-    protected static ArgumentException NotSameTypeComparison(object me, object? them) =>
+    protected static InvalidOperationException NotSameTypeComparison(object me, object? them) =>
         new($"Cannot compare {me} (of type {me.GetType()}) to {them} (of type {them?.GetType()}), because the types differ.");
 
     protected static TOut RunCast<TOut>(Any value) =>

src/Hl7.Fhir.Base/ElementModel/Types/Boolean.cs

@@ -20,7 +20,7 @@ public class Boolean(bool value) : Any, ICqlEquatable, ICqlConvertible
     public const string TRUE_LITERAL = "true";
     public const string FALSE_LITERAL = "false";
 
-    public Boolean() : this(default) { }
+    public Boolean() : this(false) { }
 
     public bool Value { get; } = value;
 
@@ -43,7 +43,7 @@ public static bool TryParse(string representation, [NotNullWhen(true)] out Boole
         }
         else
         {
-            value = default;
+            value = null;
             return false;
         }
     }

src/Hl7.Fhir.Base/ElementModel/Types/Code.cs

@@ -45,4 +45,6 @@ public override bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result)
     }
 
     public override string ToString() => $"{Value}@{System} " + Display;
+
+    // Does not support equality, equivalence and ordering in the CQL sense, so no explicit implementations of these interfaces
 }

src/Hl7.Fhir.Base/ElementModel/Types/Concept.cs

@@ -36,4 +36,6 @@ public override bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result)
     }
 
     public override string ToString() => string.Join(", ", Codes) + (Display != null ? $" \"{Display}\"" : "");
+
+    // Does not support equality, equivalence and ordering in the CQL sense, so no explicit implementations of these interfaces
 }

src/Hl7.Fhir.Base/ElementModel/Types/Date.cs

@@ -196,14 +196,11 @@ private static Date add(Date dateValue, decimal value, string unit)
 
     public bool TryEquals(Any other, [NotNullWhen(true)] out bool? result)
     {
-        if (other is Date && TryCompareTo(other, out var comparison))
-        {
-             result = comparison == 0;
-             return true;
-        }
+        result = other is Date
+            ? TryCompareTo(other, out var comparison) ? comparison == 0 : null
+            : false;
 
-        result = null;
-        return false;
+        return result is not null;
     }
 
     public static bool operator ==(Date a, Date b) => Equals(a, b);

src/Hl7.Fhir.Base/ElementModel/Types/DateTime.cs

@@ -246,14 +246,11 @@ public override bool Equals(object? obj) => obj is Any other && TryEquals(other,
 
     public bool TryEquals(Any other, [NotNullWhen(true)] out bool? result)
     {
-        if (other is DateTime && TryCompareTo(other, out var comparison))
-        {
-            result = comparison == 0;
-            return true;
-        }
+        result = other is DateTime
+            ? TryCompareTo(other, out var comparison) ? comparison == 0 : null
+            : false;
 
-        result = null;
-        return false;
+        return result is not null;
     }
 
     public static bool operator ==(DateTime a, DateTime b) => Equals(a, b);

src/Hl7.Fhir.Base/ElementModel/Types/Decimal.cs

@@ -16,7 +16,7 @@
 
 namespace Hl7.Fhir.ElementModel.Types;
 
-public class Decimal(decimal value = default) : Any, IComparable, ICqlEquatable, ICqlOrderable
+public class Decimal(decimal value = 0) : Any, IComparable, ICqlEquatable, ICqlOrderable
 {
     public decimal Value { get; } = value;
 
@@ -31,7 +31,7 @@ public static bool TryParse(string representation, [NotNullWhen(true)] out Decim
     {
         if (representation == null) throw new ArgumentNullException(nameof(representation));
 
-        value = default;
+        value = null;
 
         if (FORBIDDEN_DECIMAL_PREFIXES.Any(representation.StartsWith) || representation.EndsWith("."))
             return false;

src/Hl7.Fhir.Base/ElementModel/Types/Long.cs

@@ -68,64 +68,37 @@ public int CompareTo(object? obj)
     public static implicit operator long(Long i) => i.Value;
     public static explicit operator Long(long i) => new (i);
 
-    public static implicit operator Decimal(Long i) => new (i.Value);
-    public static implicit operator Quantity(Long i) => new (i.Value);
-
-    public static explicit operator Boolean(Long l) =>
-        l.Value switch
-        {
-            1 => Boolean.True,
-            0 => Boolean.False,
-            _ => throw new InvalidCastException($"Cannot cast Long value {l} to Boolean.")
-        };
-
-    public static implicit operator String(Long l) => new(l.ToString());
-
-    public static explicit operator Integer(Long l) =>
-        l.Value is >= int.MinValue and <= int.MaxValue
-            ? new Integer((int)l.Value)
-            : throw new InvalidCastException($"Cannot cast Long value {l} to Integer, it is too large.");
+    public static explicit operator Decimal(Long i) => RunCast<Decimal>(i);
+    public static explicit operator Quantity(Long i) => RunCast<Quantity>(i);
+    public static explicit operator Boolean(Long l) => RunCast<Boolean>(l);
+    public static explicit operator String(Long l) => RunCast<String>(l);
+    public static explicit operator Integer(Long l) => RunCast<Integer>(l);
 
     public override bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result)
     {
+        result = null;
+
         if (to == typeof(Long))
-        {
             result = this;
-            return true;
-        }
-
-        if (to == typeof(Integer))
-        {
-            result = (Integer)this;
-            return true;
-        }
-
-        if (to == typeof(Decimal))
-        {
-            result = (Decimal)this;
-            return true;
-        }
-
-        if (to == typeof(Quantity))
-        {
-            result = (Quantity)this;
-            return true;
-        }
-
-        if (to == typeof(Boolean))
-        {
-            result = (Boolean)this;
-            return true;
-        }
-
-        if (to == typeof(String))
-        {
-            result = (String)this;
-            return true;
-        }
-
-        result = default;
-        return false;
+        else if (to == typeof(Integer))
+            result = Value is >= int.MinValue and <= int.MaxValue
+                ? new Integer((int)Value)
+                : null;
+        else if (to == typeof(Decimal))
+            result = new Decimal(Value);
+        else if (to == typeof(Quantity))
+            result =  new Quantity(Value);
+        else if (to == typeof(Boolean))
+            result = Value switch
+            {
+                1 => Boolean.True,
+                0 => Boolean.False,
+                _ => null
+            };
+        else if (to == typeof(String))
+            result = new String(ToString());
+
+        return result is not null;
     }
 
     bool? ICqlEquatable.IsEqualTo(Any? other) => other is not null ? Equals(other) : null;

src/Hl7.Fhir.Base/ElementModel/Types/Quantity.cs

@@ -176,14 +176,11 @@ public bool Equals(Any other, QuantityComparison comparisonType) =>
     /// calendar durations and definite quantity durations above seconds is determined by the <paramref name="comparisonType"/></remarks>
     public bool TryEquals(Any other, QuantityComparison comparisonType, [NotNullWhen(true)] out bool? result)
     {
-        if (other is Quantity && TryCompareTo(other, comparisonType, out var comparison))
-        {
-            result = comparison == 0;
-            return true;
-        }
+        result = other is Quantity
+            ? TryCompareTo(other, comparisonType, out var comparison) ? comparison == 0 : null
+            : false;
 
-        result = null;
-        return false;
+        return result is not null;
     }
 
     public static bool operator ==(Quantity a, Quantity b) => a.CompareTo(b) == 0;
@@ -224,11 +221,7 @@ public bool TryCompareTo(Any? other, QuantityComparison comparisonType, [NotNull
             return true;
         }
 
-        if (other is not Quantity otherQ)
-        {
-            result = null;
-            return false;
-        }
+        if (other is not Quantity otherQ) throw NotSameTypeComparison(this, other);
 
         if (IsDuration && otherQ.IsDuration)
         {
@@ -277,7 +270,7 @@ Quantity normalizeToUcum(Quantity orig)
                 _ => throw new InvalidOperationException($"Unit '{orig.Unit}' is not a known calendar duration.")
             };
 
-            return new(orig.Value, ucumUnit, QuantityUnitSystem.UCUM);
+            return new Quantity(orig.Value, ucumUnit, QuantityUnitSystem.UCUM);
         }
     }
 
@@ -309,25 +302,21 @@ bool ICqlEquatable.IsEquivalentTo(Any? other) =>
         other is not null && TryEquals(other, CQL_EQUIVALENCE_COMPARISON, out var result) && result.Value;
 
     int? ICqlOrderable.CompareTo(Any? other) =>
-        other is not null && TryCompareTo(other, out var result) ? result : null;
+        other is not null && TryCompareTo(other, out var result)
+            ? result
+            : null;
 
-    public static explicit operator String(Quantity q) => new(q.ToString());
+    public static explicit operator String(Quantity q) => RunCast<String>(q);
 
     public override bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result)
     {
+        result = null;
+
         if(to == typeof(Quantity))
-        {
             result = this;
-            return true;
-        }
-
-        if (to == typeof(String))
-        {
-            result = (String)this;
-            return true;
-        }
+        else if (to == typeof(String))
+            result = new String(ToString());
 
-        result = default;
-        return false;
+        return result is not null;
     }
 }

src/Hl7.Fhir.Base/ElementModel/Types/Ratio.cs

@@ -43,24 +43,18 @@ public static bool TryParse(string representation, [NotNullWhen(true)] out Ratio
     public override int GetHashCode() => (Numerator, Denominator).GetHashCode();
     public override string ToString() => $"{Numerator}:{Denominator}";
 
-    public static explicit operator String(Ratio r) => new(r.ToString());
+    public static explicit operator String(Ratio r) => RunCast<String>(r);
 
     public override bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result)
     {
+        result = null;
+
         if(to == typeof(Ratio))
-        {
             result = this;
-            return true;
-        }
-
-        if (to == typeof(String))
-        {
-            result = (String)this;
-            return true;
-        }
+        else if (to == typeof(String))
+            result = new String(ToString());
 
-        result = default;
-        return false;
+        return result is not null;
     }
 
     public static bool operator ==(Ratio left, Ratio right) => left.Equals(right);

src/Hl7.Fhir.Base/ElementModel/Types/String.cs

@@ -8,7 +8,6 @@
 
 #nullable enable
 
-using Hl7.FhirPath.Sprache;
 using System;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
@@ -93,35 +92,26 @@ public int CompareTo(object? obj)
     public override string ToString() => Value;
 
     public static implicit operator string(String s) => s.Value;
-    public static implicit operator String(string s) => new(s);
-
-    public static explicit operator Boolean(String s) =>
-        s.TryConvertTo<Boolean>(out var result)
-            ? result
-            : throw new InvalidCastException($"Cannot cast String value {s} to Boolean.");
+    public static explicit operator String(string s) => new(s);
+    public static explicit operator Boolean(String s) => RunCast<Boolean>(s);
 
     public override bool TryConvertTo(Type to, [NotNullWhen(true)] out Any? result)
     {
+        result = null;
+
         if(to == typeof(String))
-        {
             result = this;
-            return true;
-        }
-
-        if (to == typeof(Boolean))
-        {
-            var boolValue = Value.ToLower() switch
+        else if (to == typeof(Boolean))
+            result = Value.ToLower() switch
             {
                 "true" or "t" or "yes" or "y" or "1" or "1.0" => Boolean.True,
                 "false" or "f" or "no" or "n" or "0" or "0.0" => Boolean.False,
                 _ => null
             };
+        else
+            _ = TryParseToAny(Value, to, out result);
 
-            result = boolValue;
-            return result is not null;
-        }
-
-        return TryParseToAny(Value, to, out result);
+        return result is not null;
     }
 
     private static T convertTo<T>(String s) where T:Any =>