diff --git a/README.md b/README.md
index 6402234..897dd0b 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,7 @@ None of the experiments (`infer1` and `infer2`) are outputting something useful
     pnpm experiment:infer1-direct
     pnpm experiment:infer2
     pnpm experiment:infer3
+    pnpm experiment:infer4
  
 ### Read more
  
@@ -61,3 +62,8 @@ None of the experiments (`infer1` and `infer2`) are outputting something useful
 - https://stackoverflow.com/questions/48886508/typechecker-api-how-do-i-find-inferred-type-arguments-to-a-function
 - https://blog.logrocket.com/using-typescript-transforms-to-enrich-runtime-code-3fd2863221ed/
 - https://github.com/itsdouges/typescript-transformer-handbook#transforms
+
+### Interesting libraries
+
+- https://github.com/GoogleFeud/ts-macros/
+- https://ts-morph.com
diff --git a/package.json5 b/package.json5
index 3c214e5..1f3d6e0 100644
--- a/package.json5
+++ b/package.json5
@@ -9,6 +9,8 @@
       'experiment:infer1-direct': 'ttsc -b && node build/plugins/infer1.js ./src/experiment/arithmeticInfer1.ts',
       'experiment:infer2': 'ttsc -b && node build/plugins/infer2.js ./src/experiment/arithmeticInfer2.ts',
       'experiment:infer3': 'ttsc -b && node build/plugins/infer3.js ./src/experiment/arithmeticInfer3.js',
+      'experiment:infer4': 'ttsc -b && node build/plugins/infer4.js ./src/experiment/arithmeticInfer4.ts',
+      'experiment:infer4:plugin': 'ttsc -b',
       test: 'echo "Error: no test specified" && exit 1',
    },
    keywords: [
diff --git a/src/experiment/arithmeticInfer4.ts b/src/experiment/arithmeticInfer4.ts
new file mode 100644
index 0000000..dc2f45a
--- /dev/null
+++ b/src/experiment/arithmeticInfer4.ts
@@ -0,0 +1,8 @@
+import { typed } from '../generic/infer'
+
+export const square = typed('__infer__', <T>(dep: {
+  multiply: (a: T, b: T) => T,
+  unaryMinus: (x: T) => T, // just for the experiment
+}): (a: T) => T =>
+  z => dep.multiply(z, z)
+)
diff --git a/src/generic/infer.ts b/src/generic/infer.ts
index ac038dd..92db72d 100644
--- a/src/generic/infer.ts
+++ b/src/generic/infer.ts
@@ -2,3 +2,8 @@ export function infer<T>(arg: T) : T {
   console.error('infer should be replaced with runtime type information by a magic TypeScript plugin')
   return arg
 }
+
+export function typed<T>(dep: string, arg: T) : T {
+  console.error('infer should be replaced with runtime type information by a magic TypeScript plugin')
+  return arg
+}
diff --git a/src/plugins/infer4.ts b/src/plugins/infer4.ts
new file mode 100644
index 0000000..c5e7834
--- /dev/null
+++ b/src/plugins/infer4.ts
@@ -0,0 +1,75 @@
+import { readFileSync } from "fs";
+import * as ts from "typescript";
+import { inspect } from 'util'
+
+export function infer(sourceFile: ts.SourceFile, typeChecker: ts.TypeChecker) {
+  recurse(sourceFile);
+
+  function recurse(node: ts.Node) {
+    if (ts.isCallExpression(node)) {
+      if (ts.isIdentifier(node.expression) && node.expression.escapedText === 'infer') {
+        const argNode = node.arguments[0]
+
+        if (ts.isArrowFunction(argNode)) {
+          const text = sourceFile.text.slice(argNode.pos, argNode.end)
+          console.log('infer', text)
+
+          console.log('AST')
+          console.log(node)
+          console.log()
+
+          const returnType = argNode.type.getText(sourceFile)
+          console.log('returnType', returnType)
+          // (a: number) => number
+
+          const paramNode = argNode.parameters[0]
+
+          const paramType = paramNode.type.getText(sourceFile)
+          console.log('paramType', paramType) // (a: number) => number
+          // {
+          //   multiply: (a: number, b: number) => number,
+          //   unaryMinus: (x: number) => number, // just for the experiment
+          // }
+
+          const type = typeChecker.getTypeAtLocation(paramNode)
+          const typeStr = checker.typeToString(type, paramNode, ts.TypeFormatFlags.InTypeAlias)
+          console.log('paramTypeString', typeStr)
+          // { multiply: (a: number, b: number) => number; unaryMinus: (x: number) => number; }
+        }
+
+      }
+    }
+
+    ts.forEachChild(node, recurse);
+  }
+}
+
+const fileNames = process.argv.slice(2);
+console.log('infer files', fileNames)
+
+const options = {
+  target: ts.ScriptTarget.ES2022,
+  module: ts.ModuleKind.ES2022
+}
+let program = ts.createProgram(fileNames, options);
+const checker = program.getTypeChecker()
+
+for (const sourceFile of program.getSourceFiles()) {
+  if (!sourceFile.isDeclarationFile) {
+    console.log('FILE')
+    console.log(sourceFile.fileName)
+    console.log()
+
+    console.log('SOURCE')
+    console.log(sourceFile.text)
+    console.log()
+
+    // console.log('AST')
+    // console.log(inspect(sourceFile, { depth: null, colors: true }))
+    // console.log()
+
+    console.log('INFER')
+    infer(sourceFile, checker);
+
+  }
+}
diff --git a/src/plugins/myFirstPlugin.ts b/src/plugins/myFirstPlugin.ts
new file mode 100644
index 0000000..ba2feb6
--- /dev/null
+++ b/src/plugins/myFirstPlugin.ts
@@ -0,0 +1,58 @@
+import * as ts from 'typescript';
+
+const transformer: ts.TransformerFactory<ts.SourceFile> = context => {
+  // TODO: get a reference to the program instance that the plugin is running in instead of creating a new program?
+  const program = ts.createProgram([],  {})
+  const checker = program.getTypeChecker()
+
+  return sourceFile => {
+    // For the experiment we only want to influence a single file
+    if (!sourceFile.fileName.endsWith('arithmeticInfer4.ts')) {
+      return sourceFile
+    }
+
+    const visitor = (node: ts.Node): ts.Node => {
+      // @ts-ignore
+      if (ts.isStringLiteral(node) && node.text === '__infer__') {
+        console.log('STRING LITERAL', node.text)
+        console.log(node)
+
+        const parentNode = node.parent
+        console.log('PARENT')
+        console.log(parentNode)
+
+        // TODO: validate that the parent is indeed a mathjs typed function with deps
+
+        // @ts-ignore
+        const argNode = parentNode.arguments[1]
+        const returnType = argNode.type.getText(sourceFile)
+        console.log('RETURN TYPE')
+        console.log(returnType)
+        // (a: number) => number
+
+        const paramNode = argNode.parameters[0]
+        const paramTypeSrc = paramNode.type.getText(sourceFile)
+        console.log('PARAM TYPE SRC', paramTypeSrc)
+        // {
+        //   multiply: (a: number, b: number) => number,
+        //   unaryMinus: (x: number) => number, // just for the experiment
+        // }
+
+        const type = checker.getTypeAtLocation(paramNode)
+        const paramType = checker.typeToString(type, paramNode, ts.TypeFormatFlags.InTypeAlias)
+        console.log('PARAM TYPE STRING', paramType)
+        // { multiply: (a: number, b: number) => number; unaryMinus: (x: number) => number; }
+
+        const depsAndReturnType = `{ deps: ${paramType}; return: ${returnType} }`
+
+        return ts.factory.createStringLiteral(depsAndReturnType)
+      }
+
+      return ts.visitEachChild(node, visitor, context);
+    };
+
+    return ts.visitNode(sourceFile, visitor);
+  };
+};
+
+export default transformer;
diff --git a/tsconfig.json b/tsconfig.json
index c761525..50df804 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -8,10 +8,9 @@
         "noImplicitAny": false,
         "moduleResolution": "Node",
         "module": "commonjs",
-        "plugins": [
-          {
-            "transform": "typescript-rtti/dist/transformer"
-          }
-        ]
+        "plugins": [{
+            "transform": "./src/plugins/myFirstPlugin.ts",
+            "type": "raw"
+        }]
     }
 }