initial recast setup

src/lang/recast.ts

@@ -0,0 +1,27 @@
+import { Program, BinaryExpression, BinaryPart } from "./abstractSyntaxTree";
+
+export function recast(ast: Program, previousWrittenCode = ''): string {
+  return ast.body
+    .map((statement) => {
+        if(statement.type === "ExpressionStatement") {
+            if(statement.expression.type === "BinaryExpression") {
+                return recastBinaryExpression(statement.expression);
+            }
+        }
+      return statement.type;
+    })
+    .join("\n");
+}
+
+function recastBinaryExpression(expression: BinaryExpression): string {
+    return `${recastBinaryPart(expression.left)} ${expression.operator} ${recastBinaryPart(expression.right)}`
+}
+
+function recastBinaryPart(part: BinaryPart): string {
+    if(part.type === "Literal") {
+        return String(part?.value);
+    } else if(part.type === "Identifier") {
+        return part.name;
+    }
+    throw new Error(`Cannot recast ${part}`);
+}