Address review comments

runtime/interpreter/value.go

@@ -1607,7 +1607,7 @@ func NewArrayValueWithIterator(
 	interpreter *Interpreter,
 	arrayType ArrayStaticType,
 	address common.Address,
-	count uint64,
+	countOverestimate uint64,
 	values func() Value,
 ) *ArrayValue {
 	interpreter.ReportComputation(common.ComputationKindCreateArrayValue, 1)
@@ -1652,7 +1652,7 @@ func NewArrayValueWithIterator(
 		return array
 	}
 	// must assign to v here for tracing to work properly
-	v = newArrayValueFromConstructor(interpreter, arrayType, count, constructor)
+	v = newArrayValueFromConstructor(interpreter, arrayType, countOverestimate, constructor)
 	return v
 }
 
@@ -1669,14 +1669,14 @@ func newArrayValueFromAtreeValue(
 func newArrayValueFromConstructor(
 	gauge common.MemoryGauge,
 	staticType ArrayStaticType,
-	count uint64,
+	countOverestimate uint64,
 	constructor func() *atree.Array,
 ) (array *ArrayValue) {
 	var elementSize uint
 	if staticType != nil {
 		elementSize = staticType.ElementType().elementSize()
 	}
-	baseUsage, elementUsage, dataSlabs, metaDataSlabs := common.NewArrayMemoryUsages(count, elementSize)
+	baseUsage, elementUsage, dataSlabs, metaDataSlabs := common.NewArrayMemoryUsages(countOverestimate, elementSize)
 	common.UseMemory(gauge, baseUsage)
 	common.UseMemory(gauge, elementUsage)
 	common.UseMemory(gauge, dataSlabs)
@@ -2448,6 +2448,7 @@ func (v *ArrayValue) GetMember(interpreter *Interpreter, locationRange LocationR
 		return NewHostFunctionValue(
 			interpreter,
 			sema.ArrayFilterFunctionType(
+				interpreter,
 				v.SemaType(interpreter).ElementType(false),
 			),
 			func(invocation Invocation) Value {
@@ -2973,42 +2974,20 @@ func (v *ArrayValue) Filter(
 	locationRange LocationRange,
 	procedure FunctionValue,
 ) Value {
-	filteredValuesCount := 0
 
-	invocation := NewInvocation(
-		interpreter,
-		nil,
-		nil,
-		[]Value{}, // Set later during invocation.
-		[]sema.Type{v.semaType.ElementType(false)},
-		nil,
-		locationRange,
-	)
 	iterationInvocation := func(arrayElement Value) Invocation {
-		invocation.Arguments = []Value{arrayElement}
+		invocation := NewInvocation(
+			interpreter,
+			nil,
+			nil,
+			[]Value{arrayElement},
+			[]sema.Type{v.semaType.ElementType(false)},
+			nil,
+			locationRange,
+		)
 		return invocation
 	}
 
-	err := v.array.Iterate(
-		func(item atree.Value) (bool, error) {
-			arrayElement := MustConvertStoredValue(interpreter, item)
-
-			shouldInclude, ok := procedure.invoke(iterationInvocation(arrayElement)).(BoolValue)
-			if !ok {
-				panic(errors.NewUnreachableError())
-			}
-
-			if shouldInclude {
-				filteredValuesCount++
-			}
-
-			return true, nil
-		},
-	)
-	if err != nil {
-		panic(errors.NewExternalError(err))
-	}
-
 	iterator, err := v.array.Iterator()
 	if err != nil {
 		panic(errors.NewExternalError(err))
@@ -3018,7 +2997,7 @@ func (v *ArrayValue) Filter(
 		interpreter,
 		NewVariableSizedStaticType(interpreter, v.Type.ElementType()),
 		common.ZeroAddress,
-		uint64(filteredValuesCount),
+		uint64(v.Count()), // worst case estimation.
 		func() Value {
 
 			var value Value

runtime/sema/type.go

@@ -1940,7 +1940,7 @@ func getArrayMembers(arrayType ArrayType) map[string]MemberResolver {
 					memoryGauge,
 					arrayType,
 					identifier,
-					ArrayFilterFunctionType(elementType),
+					ArrayFilterFunctionType(memoryGauge, elementType),
 					arrayTypeFilterFunctionDocString,
 				)
 			},
@@ -2264,7 +2264,7 @@ func ArrayReverseFunctionType(arrayType ArrayType) *FunctionType {
 	}
 }
 
-func ArrayFilterFunctionType(elementType Type) *FunctionType {
+func ArrayFilterFunctionType(memoryGauge common.MemoryGauge, elementType Type) *FunctionType {
 	// fun filter(_ function: ((T): Bool)): [T]
 	// funcType: elementType -> Bool
 	funcType := &FunctionType{
@@ -2285,9 +2285,7 @@ func ArrayFilterFunctionType(elementType Type) *FunctionType {
 				TypeAnnotation: NewTypeAnnotation(funcType),
 			},
 		},
-		ReturnTypeAnnotation: NewTypeAnnotation(&VariableSizedType{
-			Type: elementType,
-		}),
+		ReturnTypeAnnotation: NewTypeAnnotation(NewVariableSizedType(memoryGauge, elementType)),
 	}
 }