feat: Provide user feedback during compilation

Compiling the Stan program takes time. Give the user some indication of
what is happening.

Note that we cannot use a progress indicator here because httpstan
redirects everything sent to stderr to /dev/null to avoid overwhelming
the user with a flood of compiler info and warning messages. Progress
indicators can be used elsewhere.

Closes #111

pyproject.toml

@@ -25,7 +25,7 @@ python = "^3.7"
 aiohttp = "^3.6"
 httpstan = "^2.0.2"
 numpy = "^1.7"
-tqdm = "^4.14"
+clikit = "^0.6.2"
 
 # docs
 sphinx = { version = "^3.1.1", optional = true }

stan/model.py

@@ -1,20 +1,21 @@
 import asyncio
-import aiohttp
 import collections.abc
 import json
 import typing
 
+import aiohttp
+import google.protobuf.internal.decoder
+import httpstan.callbacks_writer_pb2 as callbacks_writer_pb2
 import httpstan.models
 import httpstan.schemas
 import httpstan.services.arguments as arguments
 import httpstan.utils
+import numpy as np
+from clikit.io import ConsoleIO
+
 import stan.common
 import stan.fit
 
-import google.protobuf.internal.decoder
-import httpstan.callbacks_writer_pb2 as callbacks_writer_pb2
-import numpy as np
-
 
 def _make_json_serializable(data: dict) -> dict:
     """Convert `data` with numpy.ndarray-like values to JSON-serializable form.
@@ -207,12 +208,21 @@ def build(program_code, data=None, random_seed=None):
     assert all(not isinstance(value, np.ndarray) for value in data.values())
 
     async def go():
+        io = ConsoleIO()
+        io.error("<info>Building...</info>")
         async with stan.common.httpstan_server() as (host, port):
+            # Check to see if model is in cache.
+            model_name = httpstan.models.calculate_model_name(program_code)
+            path, payload = f"/v1/{model_name}/params", {"data": data}
+            async with aiohttp.request("POST", f"http://{host}:{port}{path}", json=payload) as resp:
+                model_in_cache = resp.status != 404
+            io.error_line(" Found model in cache." if model_in_cache else " This may take some time.")
+            # Note: during compilation `httpstan` redirects stderr to /dev/null, making `print` impossible.
             path, payload = "/v1/models", {"program_code": program_code}
             async with aiohttp.request("POST", f"http://{host}:{port}{path}", json=payload) as resp:
                 if resp.status != 201:
                     raise RuntimeError((await resp.json())["message"])
-                model_name = (await resp.json())["name"]
+                assert model_name == (await resp.json())["name"]
 
             path, payload = f"/v1/{model_name}/params", {"data": data}
             async with aiohttp.request("POST", f"http://{host}:{port}{path}", json=payload) as resp:
@@ -222,7 +232,6 @@ async def go():
             assert len({param["name"] for param in params_list}) == len(params_list)
             param_names, dims = zip(*((param["name"], param["dims"]) for param in params_list))
             constrained_param_names = sum((tuple(param["constrained_names"]) for param in params_list), ())
-
             return Model(model_name, program_code, data, param_names, constrained_param_names, dims, random_seed)
 
     return asyncio.run(go())