simplify rollback

src/Editor.tsx

@@ -8,16 +8,7 @@ import { Type } from "./Type";
 
 import "./Editor.css"
 import { focusNextElement, focusPrevElement } from "./util/dom_trickery";
-
-interface LetInBlockState {
-  kind: "let";
-  env: any;
-  name: string;
-  value: EditorState;
-  inner: EditorState;
-  resolved: undefined | Dynamic;
-  rollback?: EditorState;
-}
+import type { LetInBlockState } from "./LetInBlock";
 
 interface LambdaBlockState {
   kind: "lambda";
@@ -50,7 +41,7 @@ interface EditorProps extends State2Props<EditorState> {
 const dontFilter = () => true;
 
 function getCommands(type) {
-  const commands = ['u', 't', 'Enter', 'Backspace', 'ArrowLeft', 'Tab'];
+  const commands = ['u', 't', 'Enter', 'Backspace', 'ArrowLeft', 'Tab', 'l', '='];
   if (getSymbol(type) === symbolFunction) {
     commands.push('c');
   }
@@ -114,6 +105,21 @@ export function Editor({state, setState, onResolve, onCancel}: EditorProps) {
       focusPrevElement();
       return;
     }
+    // l -> Let ... in ...
+    // = -> assign to name
+    if (e.key === 'l' || e.key === '=') {
+      // we become LetInBlock
+      setState({
+        kind: "let",
+        env: state.env,
+        inner: initialEditorState,
+        name: "",
+        value: state,
+        resolved: undefined,
+        rollback: state,
+      });
+      return;
+    }
   };
 
   const renderBlock = () => {