diff --git a/src/LambdaBlock.css b/src/LambdaBlock.css
index 208e0f1..bdd65ec 100644
--- a/src/LambdaBlock.css
+++ b/src/LambdaBlock.css
@@ -1,5 +1,9 @@
-.lambdaExpr {
+.lambdaBlock {
   display: inline-block;
   border: solid 1px darkgrey;
   margin: 2px;
+}
+
+.lambdaInner {
+  display: inline-block;
 }
\ No newline at end of file
diff --git a/src/LambdaBlock.tsx b/src/LambdaBlock.tsx
index abf684b..560a5cd 100644
--- a/src/LambdaBlock.tsx
+++ b/src/LambdaBlock.tsx
@@ -56,7 +56,7 @@ export function LambdaBlock({state, setState, suggestionPriority}: LambdaBlockPr
     t: getUnusedTypeVar(env),
   });
   
-  return <span>
+  return <span className="lambdaBlock">
     <span className="keyword">&#955;</span>
     &nbsp;
     <span className="lambdaInputParam">
@@ -72,7 +72,7 @@ export function LambdaBlock({state, setState, suggestionPriority}: LambdaBlockPr
     &nbsp;
     <span className="keyword">:</span>
     &nbsp;
-    <div className="lambdaExpr">
+    <div className="lambdaInner">
       <EnvContext value={innerEnv}>
         <Editor
           state={state.expr}
diff --git a/src/eval.ts b/src/eval.ts
index 843b52e..a4f2af3 100644
--- a/src/eval.ts
+++ b/src/eval.ts
@@ -98,6 +98,9 @@ export function evalCallBlock2(fnResolved: ResolvedType, inputResolved: Resolved
   try {
     // fn is a function...
     const [outType, substitutions] = assignFnSubstitutions(fnResolved.t, inputResolved.t); // may throw
+
+    // console.log('assignFn...', prettyT(fnResolved.t), prettyT(inputResolved.t), '\nout =', prettyT(outType), substitutions);
+    
   
     const mergedSubstitutions = mergeMaps(substitutions, fnResolved.substitutions, inputResolved.substitutions);
 
@@ -177,11 +180,21 @@ export function getUnusedTypeVar(env) {
 
 export function evalLambdaBlock(paramName: string, expr: EditorState, env): ResolvedType {
   const paramType = getUnusedTypeVar(env);
+  // static env: we only know the name and the type
+  const staticInnerEnv = makeInnerEnv(env, paramName, {
+    kind: "unknown", // parameter value is not statically known
+    t: paramType,
+    substitutions: new Map(),
+  });
+  const exprResolved = evalEditorBlock(expr, staticInnerEnv);
+  const lambdaT = fnType(_ => paramType)(_ => exprResolved.t);
+  const lambdaTSubstituted = substitute(lambdaT, exprResolved.substitutions, []);
+  const paramTypeSubstituted = lambdaTSubstituted.params[0](lambdaTSubstituted);
   const fn = (x: any) => {
     const innerEnv = makeInnerEnv(env, paramName, {
       kind: "value",
       i: x,
-      t: paramType,
+      t: paramTypeSubstituted,
       substitutions: new Map(),
     });
     const result = evalEditorBlock(expr, innerEnv);
@@ -189,20 +202,11 @@ export function evalLambdaBlock(paramName: string, expr: EditorState, env): Reso
       return result.i;
     }
   }
-  // static env: we only know the name and the type
-  const staticInnerEnv = makeInnerEnv(env, paramName, {
-    kind: "unknown", // parameter value is not statically known
-    t: paramType,
-    substitutions: new Map(),
-  });
-  const abstractOutput = evalEditorBlock(expr, staticInnerEnv);
-  const t = fnType(_ => paramType)(_ => abstractOutput.t);
-  const T = substitute(t, abstractOutput.substitutions, [])
   return {
     kind: "value",
-    t: T,
+    t: lambdaTSubstituted,
     i: fn,
-    substitutions: new Map(),
+    substitutions: exprResolved.substitutions,
   };
 }