--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -3671,6 +3671,47 @@ compile_lambda(char_u **arg, cctx_T *cct
 }
 
 /*
+ * Get a lambda and compile it.  Uses Vim9 syntax.
+ */
+    int
+get_lambda_tv_and_compile(
+	char_u	    **arg,
+	typval_T    *rettv,
+	int	    types_optional,
+	evalarg_T   *evalarg)
+{
+    int		r;
+    ufunc_T	*ufunc;
+    int		save_sc_version = current_sctx.sc_version;
+
+    // Get the funcref in "rettv".
+    current_sctx.sc_version = SCRIPT_VERSION_VIM9;
+    r = get_lambda_tv(arg, rettv, types_optional, evalarg);
+    current_sctx.sc_version = save_sc_version;
+    if (r != OK)
+	return r;
+
+    // "rettv" will now be a partial referencing the function.
+    ufunc = rettv->vval.v_partial->pt_func;
+
+    // Compile it here to get the return type.  The return type is optional,
+    // when it's missing use t_unknown.  This is recognized in
+    // compile_return().
+    if (ufunc->uf_ret_type == NULL || ufunc->uf_ret_type->tt_type == VAR_VOID)
+	ufunc->uf_ret_type = &t_unknown;
+    compile_def_function(ufunc, FALSE, CT_NONE, NULL);
+
+    if (ufunc->uf_def_status == UF_COMPILED)
+    {
+	// The return type will now be known.
+	set_function_type(ufunc);
+	return OK;
+    }
+    clear_tv(rettv);
+    return FAIL;
+}
+
+/*
  * parse a dict: {key: val, [key]: val}
  * "*arg" points to the '{'.
  * ppconst->pp_is_const is set if all item values are a constant.