Type check constraints (#10)

* basic impl for typing check constraints where possible

* move to dedicated dump table for all of the type tests

* add more test cases and do an actual ast pattern match to decide whether the check constraint is too complex or not

* changelog, restructure tests, and remove dependency on ReScript Core

* lints and snapshots

* ci

* ci

Author: zth

CHANGELOG.md

@@ -1,5 +1,8 @@
 # main
 
+- Add automatic parsing of PostgreSQL check constraints to generate ReScript polyvariant types for enumeration-style constraints. Supports both `column IN (value1, value2, ...)` and `column = ANY (ARRAY[value1, value2, ...])` patterns with string and integer values.
+- Remove dependency on `@rescript/core` since it's not really used.
+
 # 2.6.0
 
 - Improve `pg` bindings.

RESCRIPT.md

@@ -107,6 +107,69 @@ In order for this mode to work, you need one more thing - configure the `rescrip
 
 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.
 
+## Check Constraint Support
+
+`pgtyped-rescript` automatically analyzes PostgreSQL check constraints and generates ReScript polyvariant types for enumeration-style constraints. This provides compile-time safety for constrained database fields.
+
+### Supported Constraint Patterns
+
+The following constraint patterns are automatically detected and converted to polyvariant types:
+
+```sql
+-- Pattern 1: IN clause
+status TEXT CHECK (status IN ('published', 'draft', 'archived')),
+
+-- Pattern 2: ANY with ARRAY
+format TEXT CHECK (format = ANY (ARRAY['hardcover'::text, 'paperback'::text, 'ebook'::text])),
+
+-- Both string and integer values are supported
+priority INTEGER CHECK (priority IN (1, 2, 3, 4, 5))
+```
+
+### Generated Types
+
+For a table with these constraints:
+
+```sql
+CREATE TABLE books (
+  id SERIAL PRIMARY KEY,
+  status TEXT CHECK (status IN ('published', 'draft', 'archived')),
+  priority INTEGER CHECK (priority IN (1, 2, 3, 4, 5))
+);
+```
+
+The generated ReScript types will include:
+
+```rescript
+type result = {
+  id: int,
+  status: option<[#"published" | #"draft" | #"archived"]>,
+  priority: option<[#1 | #2 | #3 | #4 | #5]>,
+}
+```
+
+### Limitations
+
+- **Float constraints**: Not supported since ReScript polyvariants cannot represent float literals
+- **Complex constraints**: Only simple enumeration patterns are supported (no `BETWEEN`, `OR` logic, function calls, etc.)
+- **Mixed types**: Constraints mixing different data types in the same clause are not supported
+
+### Example
+
+```sql
+/* @name getBooksByStatus */
+SELECT * FROM books WHERE status = :status;
+```
+
+```rescript
+// The generated function will accept a polyvariant for status
+let books = await client->GetBooksByStatus.many({
+  status: #published  // Compile-time checked against the database constraint!
+})
+```
+
+This feature works seamlessly with both separate SQL files and SQL-in-ReScript modes.
+
 ## API
 
 ### `PgTyped`

package-lock.json

@@ -39,7 +39,6 @@
     "@pgtyped/parser": "^2.1.0",
     "@pgtyped/wire": "^2.2.0",
     "@rescript/tools": "0.6.4",
-    "@rescript/core": "1.6.0",
     "camel-case": "^4.1.1",
     "chalk": "^4.0.0",
     "chokidar": "^3.3.1",
@@ -66,7 +65,6 @@
     "rescript": "11.1.0"
   },
   "peerDependencies": {
-    "@rescript/core": ">= 1.3.0",
     "rescript": ">= 11.1.0"
   }
 }

packages/cli/package.json

@@ -7,7 +7,5 @@
     "module": "commonjs",
     "in-source": true
   },
-  "suffix": ".js",
-  "bs-dependencies": ["@rescript/core"],
-  "bsc-flags": ["-open RescriptCore"]
+  "suffix": ".js"
 }