feature: Export the type of a recipe as Produce (#968)

* feature: add type for producer function

* IProducer -> Producer

Co-authored-by: Michel Weststrate <mweststrate@gmail.com>

src/types/types-external.ts

@@ -252,6 +252,11 @@ export interface IProduceWithPatches {
 	): Promise<PatchesTuple<Base>>
 }
 
+/**
+ * The type for `recipe function`
+ */
+export type Producer<T> = (draft: Draft<T>) => ValidRecipeReturnType<Draft<T>> | Promise<ValidRecipeReturnType<Draft<T>>>
+
 // Fixes #507: bili doesn't export the types of this file if there is no actual source in it..
 // hopefully it get's tree-shaken away for everyone :)
 export function never_used() {}