return code for pal (#844)

docs/modules/chains/examples/pal.ipynb

@@ -21,6 +21,24 @@
     "from langchain import OpenAI"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "9a58e15e",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "llm = OpenAI(model_name='code-davinci-002', temperature=0, max_tokens=512)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "095adc76",
+   "metadata": {},
+   "source": [
+    "## Math Prompt"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 2,
@@ -28,7 +46,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "llm = OpenAI(model_name='code-davinci-002', temperature=0, max_tokens=512)\n",
     "pal_chain = PALChain.from_math_prompt(llm, verbose=True)"
    ]
   },
@@ -64,7 +81,7 @@
       "    result = total_pets\n",
       "    return result\u001b[0m\n",
       "\n",
-      "\u001b[1m> Finished PALChain chain.\u001b[0m\n"
+      "\u001b[1m> Finished chain.\u001b[0m\n"
      ]
     },
     {
@@ -82,6 +99,14 @@
     "pal_chain.run(question)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "0269d20a",
+   "metadata": {},
+   "source": [
+    "## Colored Objects"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 5,
@@ -89,7 +114,6 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "llm = OpenAI(model_name='code-davinci-002', temperature=0, max_tokens=512)\n",
     "pal_chain = PALChain.from_colored_object_prompt(llm, verbose=True)"
    ]
   },
@@ -147,10 +171,94 @@
     "pal_chain.run(question)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "fc3d7f10",
+   "metadata": {},
+   "source": [
+    "## Intermediate Steps\n",
+    "You can also use the intermediate steps flag to return the code executed that generates the answer."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "id": "9d2d9c61",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "pal_chain = PALChain.from_colored_object_prompt(llm, verbose=True, return_intermediate_steps=True)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "id": "b29b971b",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "question = \"On the desk, you see two blue booklets, two purple booklets, and two yellow pairs of sunglasses. If I remove all the pairs of sunglasses from the desk, how many purple items remain on it?\""
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "id": "a2c40c28",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "\n",
+      "\n",
+      "\u001b[1m> Entering new PALChain chain...\u001b[0m\n",
+      "\u001b[32;1m\u001b[1;3m# Put objects into a list to record ordering\n",
+      "objects = []\n",
+      "objects += [('booklet', 'blue')] * 2\n",
+      "objects += [('booklet', 'purple')] * 2\n",
+      "objects += [('sunglasses', 'yellow')] * 2\n",
+      "\n",
+      "# Remove all pairs of sunglasses\n",
+      "objects = [object for object in objects if object[0] != 'sunglasses']\n",
+      "\n",
+      "# Count number of purple objects\n",
+      "num_purple = len([object for object in objects if object[1] == 'purple'])\n",
+      "answer = num_purple\u001b[0m\n",
+      "\n",
+      "\u001b[1m> Finished chain.\u001b[0m\n"
+     ]
+    }
+   ],
+   "source": [
+    "result = pal_chain({\"question\": question})"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 11,
+   "id": "efddd033",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "\"# Put objects into a list to record ordering\\nobjects = []\\nobjects += [('booklet', 'blue')] * 2\\nobjects += [('booklet', 'purple')] * 2\\nobjects += [('sunglasses', 'yellow')] * 2\\n\\n# Remove all pairs of sunglasses\\nobjects = [object for object in objects if object[0] != 'sunglasses']\\n\\n# Count number of purple objects\\nnum_purple = len([object for object in objects if object[1] == 'purple'])\\nanswer = num_purple\""
+      ]
+     },
+     "execution_count": 11,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "result['intermediate_steps']"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "4ab20fec",
+   "id": "dfd88594",
    "metadata": {},
    "outputs": [],
    "source": []

langchain/chains/pal/base.py

@@ -27,6 +27,7 @@ class PALChain(Chain, BaseModel):
     python_globals: Optional[Dict[str, Any]] = None
     python_locals: Optional[Dict[str, Any]] = None
     output_key: str = "result"  #: :meta private:
+    return_intermediate_steps: bool = False
 
     class Config:
         """Configuration for this pydantic object."""
@@ -48,7 +49,10 @@ class PALChain(Chain, BaseModel):
 
         :meta private:
         """
-        return [self.output_key]
+        if not self.return_intermediate_steps:
+            return [self.output_key]
+        else:
+            return [self.output_key, "intermediate_steps"]
 
     def _call(self, inputs: Dict[str, str]) -> Dict[str, str]:
         llm_chain = LLMChain(llm=self.llm, prompt=self.prompt)
@@ -58,7 +62,10 @@ class PALChain(Chain, BaseModel):
         )
         repl = PythonREPL(_globals=self.python_globals, _locals=self.python_locals)
         res = repl.run(code + f"\n{self.get_answer_expr}")
-        return {self.output_key: res.strip()}
+        output = {self.output_key: res.strip()}
+        if self.return_intermediate_steps:
+            output["intermediate_steps"] = code
+        return output
 
     @classmethod
     def from_math_prompt(cls, llm: BaseLLM, **kwargs: Any) -> PALChain: