further improved keyboard handling

src/CallBlock.tsx

@@ -1,6 +1,6 @@
 import { useState } from "react";
 
-import { apply, UnifyError, assignFn, getType } from "dope2";
+import { apply, UnifyError, assignFn, getType, getSymbol, symbolFunction } from "dope2";
 
 import { Editor, type EditorState } from "./Editor";
 import { Value } from "./Value";
@@ -97,7 +97,8 @@ export function CallBlock({ state, setState, onResolve }: CallBlockProps) {
     <FunctionHeader
       fn={state.fn}
       setFn={setFn}
-      onFnResolve={onFnResolve} />
+      onFnResolve={onFnResolve}
+      input={state.input} />
     <div className="functionParams">
       <div className="outputParam">
         {/* Sequence of input parameters */}
@@ -116,7 +117,7 @@ export function CallBlock({ state, setState, onResolve }: CallBlockProps) {
   </span>;
 }
 
-function FunctionHeader({ fn, setFn, onFnResolve }) {
+function FunctionHeader({ fn, setFn, input, onFnResolve }) {
   if (fn.kind === "call") {
     // if the function we're calling is itself the result of a function call,
     // then we are anonymous, and so we don't draw a function name
@@ -129,9 +130,28 @@ function FunctionHeader({ fn, setFn, onFnResolve }) {
     return <FunctionHeader
       fn={fn.fn}
       setFn={fnFn => setFn({...fn, fn: fnFn})}
-      onFnResolve={onFnFnResolve} />;
+      onFnResolve={onFnFnResolve}
+      input={fn.input} />;
   }
   else {
+    const filterCompatibleFns = ([_name, dynamic]: [string, Dynamic]) => {
+      if (input.resolved) {
+        try {
+          const type = getType(dynamic);
+          if (getSymbol(type) !== symbolFunction) {
+            return false;
+          }
+          assignFn(type, getType(input.resolved));
+        } catch (e) {
+          if (!(e instanceof UnifyError)) {
+            throw e;
+          }
+          return false;
+        }  
+      }
+      return true;
+    }
+  
     //  end of recursion - draw function name
     return <div className="functionName">
       &#119891;&#119899;&nbsp;
@@ -141,7 +161,7 @@ function FunctionHeader({ fn, setFn, onFnResolve }) {
         focus={false}
         onResolve={onFnResolve}
         onCancel={() => {/*todo*/}}
-        filter={() => true} />
+        filter={filterCompatibleFns} />
     </div>;
   }
 }