Improve docs & Add JSON decode example (#121)

README.md

@@ -123,19 +123,21 @@ You can implement your prompt flow in a function decorated by `sgl.function`.
 You can then invoke the function with `run` or `run_batch`.
 The system will manage the state, chat template, parallelism and batching for you.
 
+The complete code for the examples below can be found at [readme_examples.py](examples/usage/readme_examples.py)
+
 ### Control Flow
 You can use any Python code within the function body, including control flow, nested function calls, and external libraries.
 
 ```python
 @sgl.function
-def control_flow(s, question):
-    s += "To answer this question: " + question + ", "
-    s += "I need to use a " + sgl.gen("tool", choices=["calculator", "web browser"]) + ". "
+def tool_use(s, question):
+    s += "To answer this question: " + question + ". "
+    s += "I need to use a " + sgl.gen("tool", choices=["calculator", "search engine"]) + ". "
 
     if s["tool"] == "calculator":
         s += "The math expression is" + sgl.gen("expression")
-    elif s["tool"] == "web browser":
-        s += "The website url is" + sgl.gen("url")
+    elif s["tool"] == "search engine":
+        s += "The key word to search is" + sgl.gen("word")
 ```
 
 ### Parallelism
@@ -170,6 +172,8 @@ def image_qa(s, image_file, question):
     s += sgl.assistant(sgl.gen("answer", max_tokens=256)
 ```
 
+See also [srt_example_llava.py](examples/quick_start/srt_example_llava.py).
+
 ### Constrained Decoding
 Use `regex` to specify a regular expression as a decoding constraint.
 This is only supported for local models.
@@ -185,6 +189,35 @@ def regular_expression_gen(s):
     )
 ```
 
+### JSON Decoding
+
+```python
+character_regex = (
+    r"""\{\n"""
+    + r"""    "name": "[\w\d\s]{1,16}",\n"""
+    + r"""    "house": "(Gryffindor|Slytherin|Ravenclaw|Hufflepuff)",\n"""
+    + r"""    "blood status": "(Pure-blood|Half-blood|Muggle-born)",\n"""
+    + r"""    "occupation": "(student|teacher|auror|ministry of magic|death eater|order of the phoenix)",\n"""
+    + r"""    "wand": \{\n"""
+    + r"""        "wood": "[\w\d\s]{1,16}",\n"""
+    + r"""        "core": "[\w\d\s]{1,16}",\n"""
+    + r"""        "length": [0-9]{1,2}\.[0-9]{0,2}\n"""
+    + r"""    \},\n"""
+    + r"""    "alive": "(Alive|Deceased)",\n"""
+    + r"""    "patronus": "[\w\d\s]{1,16}",\n"""
+    + r"""    "bogart": "[\w\d\s]{1,16}"\n"""
+    + r"""\}"""
+)
+
+@sgl.function
+def character_gen(s, name):
+    s += name + " is a character in Harry Potter. Please fill in the following information about him/her.\n"
+    s += sgl.gen("json_output", max_tokens=256, regex=character_regex)
+```
+
+See also [json_decode.py](examples/usage/json_decode.py).
+
+
 ### Batching
 Use `run_batch` to run a batch of requests with continuous batching.