docs for SQL-in-ReScript mode

RESCRIPT.md

@@ -5,15 +5,14 @@ This small readme focuses on the differences between regular `pgtyped` and this
 ## Differences to regular `pgtyped`
 
 - It outputs ReScript instead of TypeScript.
-- It only supports using SQL files, not SQL-in-ReScript (yet! support coming at some point).
 
 Everything else should work pretty much the same as stock `pgtyped`.
 
 ## Getting started
 
 Make sure you have ReScript `v11.1`, and [ReScript Core](https://github.com/rescript-association/rescript-core) (plus `RescriptCore` opened globally).
 
-1. `npm install -D pgtyped-rescript`
+1. `npm install -D pgtyped-rescript rescript-embed-lang` (install `rescript-embed-lang` if you want to use the SQL-in-ReScript mode)
 2. `npm install @pgtyped/runtime pg rescript @rescript/core` (`@pgtyped/runtime` and `pg` are the only required runtime dependencies of pgtyped)
 3. Create a PgTyped `pgtyped.config.json` file.
 4. Run `npx pgtyped-rescript -w -c pgtyped.config.json` to start PgTyped in watch mode.
@@ -29,18 +28,27 @@ Here's a sample `pgtyped.config.json` file:
       "mode": "sql",
       "include": "**/*.sql",
       "emitTemplate": "{{dir}}/{{name}}__sql.res"
+    },
+    {
+      "mode": "res",
+      "include": "**/*.res",
+      "emitTemplate": "{{dir}}/{{name}}__sql.res"
     }
   ],
-  "srcDir": "./src/sql",
+  "srcDir": "./src",
   "dbUrl": "postgres://pgtyped:pgtyped@localhost/pgtyped"
 }
 ```
 
-> Notice how we're configuring what we want the generated ReScript files to be named under `emitTemplate`.
+> Notice how we're configuring what we want the generated ReScript files to be named under `emitTemplate`. For SQL-in-ReScript mode, you need to configure the generated file names exactly as above.
+
+Please refer to the `pgtyped` docs for all configuration options.
 
-Please refer to the `pgtyped` docs for all configuration options. The only thing that's important to remember for the ReScript version is that _only SQL files are supported_.
+## Separate SQL files mode
 
-Now we can create a SQL file in `src/sql`. We call this one `books.sql`:
+`pgtyped-rescript` supports writing queries in separate SQL files, as well as embedded directly in ReScript source code. Below details the separate SQL files approach:
+
+Create a SQL file anywhere in `src`. We call this one `books.sql`:
 
 ```sql
 /* @name findBookById */
@@ -76,6 +84,28 @@ let main = async () => {
 main()->Promise.done
 ```
 
+## SQL-in-ReScript
+
+Optionally, you can write SQL directly in your ReScript code and have a seamless, fully typed experience. The above example but with SQL-in-ReScript:
+
+```rescript
+let query = %sql.one(`
+  /* @name findBookById */
+  SELECT * FROM books WHERE id = :id!;
+`)
+
+let res = await client->query({id: 1})
+Console.log(res)
+```
+
+In order for this mode to work, you need one more thing - configure the `rescript-embed-lang` PPX in `rescript.json`:
+
+```json
+"ppx-flags": ["rescript-embed-lang/ppx"],
+```
+
+With that, you should be able to write queries directly in your ReScript source, and with the `watch` mode enabled have a seamless experience with types autogenerated and wired up for you.
+
 ## API
 
 ### `PgTyped`