diff --git a/expressions/src/completion/descriptionDictionary.ts b/expressions/src/completion/descriptionDictionary.ts
index 2aaa3dd..44b1c8e 100644
--- a/expressions/src/completion/descriptionDictionary.ts
+++ b/expressions/src/completion/descriptionDictionary.ts
@@ -9,7 +9,7 @@ export function isDescriptionDictionary(x: ExpressionData): x is DescriptionDict
 
 export class DescriptionDictionary extends Dictionary {
   private readonly descriptions = new Map<string, string>();
-  public complete: boolean = true;
+  public complete = true;
 
   constructor(...pairs: DescriptionPair[]) {
     super();
diff --git a/expressions/src/data/null.ts b/expressions/src/data/null.ts
index 78593df..71947cb 100644
--- a/expressions/src/data/null.ts
+++ b/expressions/src/data/null.ts
@@ -1,8 +1,6 @@
-import {ExpressionData, ExpressionDataInterface, Kind} from "./expressiondata";
+import {ExpressionDataInterface, Kind} from "./expressiondata";
 
 export class Null implements ExpressionDataInterface {
-  constructor() {}
-
   public readonly kind = Kind.Null;
 
   public primitive = true;
diff --git a/expressions/src/data/number.ts b/expressions/src/data/number.ts
index 960e9c3..9a3dec4 100644
--- a/expressions/src/data/number.ts
+++ b/expressions/src/data/number.ts
@@ -8,7 +8,7 @@ export class NumberData implements ExpressionDataInterface {
   public primitive = true;
 
   coerceString(): string {
-    if (this.value === -0) {
+    if (Object.is(this.value, -0)) {
       return "0";
     }
 
diff --git a/expressions/src/data/replacer.ts b/expressions/src/data/replacer.ts
index 4217952..c73530d 100644
--- a/expressions/src/data/replacer.ts
+++ b/expressions/src/data/replacer.ts
@@ -10,7 +10,7 @@ import {StringData} from "./string";
  *
  * See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify#replacer
  */
-export function replacer(key: string, value: any): any {
+export function replacer(_key: string, value: unknown): unknown {
   if (value instanceof Null) {
     return null;
   }
@@ -34,7 +34,7 @@ export function replacer(key: string, value: any): any {
   if (value instanceof Dictionary) {
     const pairs = value.pairs();
 
-    const r: any = {};
+    const r: Record<string, unknown> = {};
     for (const p of pairs) {
       r[p.key] = p.value;
     }
diff --git a/expressions/src/data/reviver.ts b/expressions/src/data/reviver.ts
index 4d1168b..3838e2a 100644
--- a/expressions/src/data/reviver.ts
+++ b/expressions/src/data/reviver.ts
@@ -1,7 +1,7 @@
 import {Array as dArray} from "./array";
 import {BooleanData} from "./boolean";
 import {Dictionary} from "./dictionary";
-import {ExpressionData, Pair} from "./expressiondata";
+import {ExpressionData} from "./expressiondata";
 import {Null} from "./null";
 import {NumberData} from "./number";
 import {StringData} from "./string";
@@ -11,7 +11,7 @@ import {StringData} from "./string";
  *
  * See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse#reviver
  */
-export function reviver(key: string, val: any): ExpressionData {
+export function reviver(_key: string, val: unknown): ExpressionData {
   if (val === null) {
     return new Null();
   }
@@ -25,25 +25,22 @@ export function reviver(key: string, val: any): ExpressionData {
   }
 
   if (typeof val === "boolean") {
-    return new BooleanData(val as boolean);
+    return new BooleanData(val);
   }
 
   if (Array.isArray(val)) {
-    return new dArray(...val);
+    return new dArray(...(val as ExpressionData[]));
   }
 
   if (typeof val === "object") {
     return new Dictionary(
-      ...Object.keys(val).map(
-        k =>
-          ({
-            key: k,
-            value: val[k]
-          } as Pair)
-      )
+      ...Object.keys(val).map(k => ({
+        key: k,
+        value: val[k as keyof typeof val]
+      }))
     );
   }
 
   // Pass through value
-  return val;
+  return val as ExpressionData;
 }
diff --git a/expressions/src/funcs/contains.ts b/expressions/src/funcs/contains.ts
index d074d0f..e21f44d 100644
--- a/expressions/src/funcs/contains.ts
+++ b/expressions/src/funcs/contains.ts
@@ -1,4 +1,4 @@
-import {Array, BooleanData, ExpressionData, Kind} from "../data";
+import {BooleanData, ExpressionData, Kind} from "../data";
 import {equals} from "../result";
 import {FunctionDefinition} from "./info";
 
@@ -19,7 +19,7 @@ export const contains: FunctionDefinition = {
         return new BooleanData(ls.toLowerCase().includes(rs.toLowerCase()));
       }
     } else if (left.kind === Kind.Array) {
-      const la = left as Array;
+      const la = left;
       if (la.values().length === 0) {
         return new BooleanData(false);
       }
diff --git a/expressions/src/funcs/format.ts b/expressions/src/funcs/format.ts
index 8c5478c..93bfa5c 100644
--- a/expressions/src/funcs/format.ts
+++ b/expressions/src/funcs/format.ts
@@ -15,7 +15,7 @@ export const format: FunctionDefinition = {
 
     while (index < fs.length) {
       const lbrace = fs.indexOf("{", index);
-      let rbrace = fs.indexOf("}", index);
+      const rbrace = fs.indexOf("}", index);
 
       // Left brace
       if (lbrace >= 0 && (rbrace < 0 || rbrace > lbrace)) {
@@ -81,7 +81,7 @@ function safeCharAt(string: string, index: number): string {
 function readArgIndex(string: string, startIndex: number): ArgIndex {
   // Count the number of digits
   let length = 0;
-  while (true) {
+  for (;;) {
     const nextChar = safeCharAt(string, startIndex + length);
     if (nextChar >= "0" && nextChar <= "9") {
       length++;
@@ -112,9 +112,3 @@ interface ArgIndex {
   result: number;
   endIndex: number;
 }
-
-interface FormatSpecifiers {
-  success: boolean;
-  result: string;
-  rbrace: number;
-}
diff --git a/expressions/src/funcs/fromjson.ts b/expressions/src/funcs/fromjson.ts
index 6546b2a..5eca009 100644
--- a/expressions/src/funcs/fromjson.ts
+++ b/expressions/src/funcs/fromjson.ts
@@ -18,7 +18,7 @@ export const fromjson: FunctionDefinition = {
     }
 
     try {
-      return JSON.parse(is, reviver);
+      return JSON.parse(is, reviver) as ExpressionData;
     } catch (e) {
       throw new ExpressionEvaluationError("Error parsing JSON when evaluating fromJson", {cause: e});
     }
diff --git a/expressions/src/funcs/join.ts b/expressions/src/funcs/join.ts
index 38bb92f..92750ae 100644
--- a/expressions/src/funcs/join.ts
+++ b/expressions/src/funcs/join.ts
@@ -1,4 +1,4 @@
-import {Array, ExpressionData, Kind, StringData} from "../data";
+import {ExpressionData, Kind, StringData} from "../data";
 import {FunctionDefinition} from "./info";
 
 export const join: FunctionDefinition = {
@@ -23,7 +23,7 @@ export const join: FunctionDefinition = {
 
       // Convert items to strings
       return new StringData(
-        (args[0] as Array)
+        args[0]
           .values()
           .map(item => item.coerceString())
           .join(separator)