Non-JSON Schema and Examples in PDL

### Non-json schema Basically, pdl engine first extracts json-looking string from LLM output, then parses it. For example, if the schema is a json object, the engine tries to match a curly brace using regular expression. If it fails to parse json, that's an error. There are 4 cases where it doesn't parse json. 1. If the schema is `str`, it just treats the entire output as the string. It doesn't look for quotation marks, and it doesn't run the parser. You can also add constraints to `str`. For example, if the schema is `str { min: 100 }`, it makes sure that the length of the entire output is at least 100 characters. 2. If the schema is `yesno`, it makes sure that the LLM's output is either `yes` or `no`. You cannot mix it with other json schema because `yes` and `no` are not valid json values. If yes/no is all you need, `yesno` is better than `bool` because LLMs are usually better at English than json. This type is later converted to a boolean value, `serde_json::Value::Bool` in Rust. 3. If the schema is `code`, it looks for a [markdown code block](https://github.github.com/gfm/#fenced-code-blocks). This type is later converted to a string value, `serde_json::Value::String` in Rust. The string is the content of the fenced code block, without the fences. 4. If the schema is `tasklist`, it looks for a [markdown task list](https://github.github.com/gfm/#task-list-items-extension-). It extracts the task list from LLM output and converts the list to a string value, `serde_json::Value::String` in Rust. ## Examples ### An image ``` <|user|> <|media(assets/sample_image.png)|> What do you see in the image? ``` When you run this pdl file with a multi-modal model, the model will tell you what it sees in the image. ### A simple schema 1: boolean ``` <|schema|> bool <|user|> Is Rust a strictly typed programming language? Just say "true" or "false". ``` If the model's response has no "true" or "false", it will automatically prompt the model to "just say true or false". ### A simple schema 2: yes/no ``` <|schema|> yesno <|user|> Is Rust a strictly typed programming language? Just say yes or no. ``` It's like a boolean schema, but it will make the model say yes or no. It's better sometimes since most models are better at English than json.

PDL supports non-JSON schema types, including string, yes/no, code, and tasklist, which allow for flexible output parsing and validation, and provides examples of using these schema types, such as image embedding and simple boolean and yes/no schemas.