Add definition merging boilerplate code

src/api.ts

@@ -1,4 +1,4 @@
-import { parse as _parse } from '@0no-co/graphql.web';
+import { Kind, parse as _parse } from '@0no-co/graphql.web';
 import type { DocumentNode } from '@0no-co/graphql.web';
 
 import type {
@@ -59,9 +59,35 @@ function graphql<
   const Fragments extends readonly [...FragmentDefDecorationLike[]],
 >(
   input: In,
-  _fragments?: Fragments
+  fragments?: Fragments
 ): getDocumentNode<In, Schema, getFragmentsOfDocumentsRec<Fragments>> {
-  return _parse(input) as any;
+  const fragmentNames = new Map<string, unknown>();
+  const definitions = [...source.definitions];
+  const source = _parse(input);
+  for (const document of fragments) {
+    for (const definition of document.definitions) {
+      if (definition.kind === Kind.FRAGMENT_DEFINITION) {
+        const name = definition.name.value;
+        if (!fragmentNames.has(definition.name.value)) {
+          fragmentNames.set(definition.name.value, definition);
+          definitions.push(definition);
+        } else if (
+          process.env.NODE_ENV !== 'production' &&
+          fragmentNames.get(name) !== definition
+        ) {
+          // Fragments with the same names is expected to have the same contents
+          console.warn(
+            '[WARNING: Duplicate Fragment] A fragment with name `' +
+              name +
+              '` already exists in this document.\n' +
+              'While fragment names may not be unique across your source, each name must be unique per document.'
+          );
+        }
+      }
+    }
+  }
+
+  return { kind: Kind.DOCUMENT, definitions };
 }
 
 /** A GraphQL `DocumentNode` with attached generics for its result data and variables.

src/namespace.ts

@@ -1,4 +1,4 @@
-import type { Kind } from '@0no-co/graphql.web';
+import type { Kind, DocumentNode } from '@0no-co/graphql.web';
 import type { DocumentNodeLike } from './parser';
 import type { obj } from './utils';
 
@@ -33,7 +33,7 @@ type getFragmentsOfDocumentsRec<Documents> = Documents extends readonly [
   infer Document,
   ...infer Rest,
 ]
-  ? (Document extends FragmentDefDecorationLike
+  ? (Document extends { [$tada.fragmentDef]?: any }
       ? Exclude<Document[$tada.fragmentDef], undefined> extends infer FragmentDef extends {
           kind: Kind.FRAGMENT_DEFINITION;
           name: any;
@@ -45,7 +45,7 @@ type getFragmentsOfDocumentsRec<Documents> = Documents extends readonly [
       getFragmentsOfDocumentsRec<Rest>
   : {};
 
-interface FragmentDefDecorationLike {
+interface FragmentDefDecorationLike extends DocumentNode {
   [$tada.fragmentDef]?: {
     readonly [$tada.fragmentId]: symbol;
     kind: Kind.FRAGMENT_DEFINITION;