scratch の typo
(defpackage :a (:use :cl))
;;⇒ #<PACKAGE "A">

(in-package :a)
;;⇒ #<PACKAGE "A">

(series::install)

(info.read-eval-print.mongo::def-api "test" "foo")
;;⇒ FOO.SCAN

(series:collect-first (foo.scan nil))
;;⇒ {"_id": ObjectId("51734E4BCF15ED0A74C21E61"), "a": "hello", "b": 1}

(series:collect (foo.scan nil))
;;⇒ ({"_id": ObjectId("51734E4BCF15ED0A74C21E61"), "a": "hello", "b": 1}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E62"), "a": "hello", "b": 2}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E63"), "a": "hello", "b": 3}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E64"), "a": "hello", "b": 4}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E65"), "a": "hello", "b": 5}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E66"), "a": "hello", "b": 6}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E67"), "a": "hello", "b": 7}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E68"), "a": "hello", "b": 8}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E69"), "a": "hello", "b": 9}
;;    {"_id": ObjectId("51734E4BCF15ED0A74C21E6A"), "a": "hello", "b": 10}
;;    {"_id": ObjectId("51734E4DCF15ED0A74C21E6B"), "a": "world", "b": 1})

(foo.find-one nil)
;;⇒ {"_id": ObjectId("51734E4BCF15ED0A74C21E61"), "a": "hello", "b": 1}

(foo.find-all nil :projection '((:_id)))
;;⇒ ({"a": "hello", "b": 1} {"a": "hello", "b": 2} {"a": "hello", "b": 3}
;;    {"a": "hello", "b": 4} {"a": "hello", "b": 5} {"a": "hello", "b": 6}
;;    {"a": "hello", "b": 7} {"a": "hello", "b": 8} {"a": "hello", "b": 9}
;;    {"a": "hello", "b": 10} {"a": "world", "b": 1})