Add new templates
diff --git a/docs/TEMPLATES.md b/docs/TEMPLATES.md
index abb971f..b6df123 100644
--- a/docs/TEMPLATES.md
+++ b/docs/TEMPLATES.md
@@ -88,6 +88,7 @@
}
}
```
+In this example, the `let` combinator is used to capture the desired field name: it binds the `field` variable to the field name.
## Forward
@@ -100,5 +101,15 @@
composer.retain(p => require('lodash').omit(p, ...fields), composer.mask(composition)),
({ params, result }) => Object.assign(result, require('lodash').pick(params, ...fields)))
-composer.forward(['user', 'password'], evilComposition)
+composer.forward(['user', 'password'], untrustedComposition)
+```
+
+## Inject and extract
+
+The following combinators make it possible to bind a field of the parameter object to the value of the homonymous variable and vice versa.
+```javascript
+composer.inject = v => composer.seq(composer.let({ v }, params => { params[v] = eval(v) }))
+composer.extract = v => composer.seq(composer.let({ v }, params => { eval(`${v} = params[v]`); delete params[v] }))
+
+composer.let({ token: null }, 'getSecretToken', composer.extract('token'), untrustedAction, composer.inject('token'), trustedAction)
```
