Update README.md

README.md

@@ -5,6 +5,8 @@
   <strong>GraphQL TypeScript Generator</strong>
 </p>
 
+## Example
+
 <table>
 <tr>
   <th>From GraphQL</th>
@@ -114,6 +116,84 @@ type IssuesQuery = () => {
 </tr>
 </table>
 
+## Installation
+
+```bash
+npm install megaera
+```
+
+## Usage
+
+```bash
+megaera --schema=schema.graphql ./src/**/*.graphql
+```
+
+Import generated code in your TypeScript file:
+
+```ts
+import { IssuesQuery } from './query.graphql.js'
+
+const { issues } = await octokit.graphql<ReturnType<IssuesQuery>>(IssuesQuery)
+```
+
+## FAQ
+
+### Why query string is copied to TypeScript file as well?
+
+To make it easier to import queries in TypeScript projects. As well to connect
+generated output types with query source code.
+
+This allows for library authors to create a function that accepts a query, and
+infers the return type from the query, as well as the types of the variables.
+
+For example, wrap [Octokit](https://github.com/octokit/octokit.js) in a function
+that accepts a query and returns the result:
+
+```ts
+import { Query, Variables } from 'megaera'
+import { IssuesQuery } from './query.graphql.js'
+
+function query<T extends Query>(query: T, variables?: Variables<T>) {
+  return octokit.graphql<ReturnType<T>>(query, variables)
+}
+
+// Return type, and types of variables are inferred from the query.
+const { issues } = await query(IssuesQuery, { login: 'webpod' })
+```
+
+### Does Megaera support fragments?
+
+Yes, Megaera fully supports fragments. Fragments are generated as separate types,
+and can be used independently.
+
+```graphql
+query IssuesQuery($login: String) {
+  issues(login: $login) {
+    totalCount
+    nodes {
+      ...Issue
+    }
+  }
+}
+
+fragment Issue on Issue {
+  number
+  author {
+    login
+  }
+  createdAt
+  closedAt
+}
+```
+
+The generated TypeScript code will have a type `Issue` that can be used independently:
+
+```ts
+import { Issue, IssuesQuery } from './query.graphql.js'
+
+const firstIssue: Issue = query(IssuesQuery).issues.nodes[0]
+```
+
 ## License
 
 [MIT](LICENSE)