BetaCalendars Calendar Query

Calendar Query is a small Clojure library for querying civil-date data with ordinary maps and EDN. It provides inclusive date sources, a checked predicate language, transducer-based filtering and projection, calendar windows, a data-valued plan explanation, and pure month-grid projections.

Source repository: mateopedersen/betacalendars-calendar-query.

Dates use java.time.LocalDate; month values use java.time.YearMonth. There are no runtime dependencies beyond Clojure and the JDK.

Install

net.clojars.mateopedersen/calendar-query {:mvn/version "0.1.0"}

Query dates

(require '[betacalendars.calendar-query :as q])

(def query
  {:from "2026-11-01"
   :to "2026-11-30"
   :where [:and
           [:weekday-in #{:monday :wednesday :friday}]
           [:not [:weekend?]]]
   :derive {:quarter :quarter :iso-week :iso-week}
   :select [:date :weekday :quarter :iso-week]
   :serializable? true})

(q/execute query)
;; => an eduction of selected maps, with ISO date strings

The same query can run over caller-owned records:

(transduce (q/compile-query query) conj []
           (q/reducible-date-range "2026-11-01" "2026-11-30"))

compile-query supports streaming predicates, built-in derivation, projection, :take, and :drop. Global :order-by and :group-by operations use execute and materialize matching rows. Grouping can return matching records or a small set of built-in aggregates. explain reports that materialization:

(q/explain query)
;; => EDN map with source bounds, plan steps, and materialization flags

Calendar shapes

(q/project-month "2027-01" {:week-start :monday :adjacent-days :include})
(q/blank-grid {:rows 6 :columns 7 :week-start :monday})
(into [] (q/calendar-windows :iso-week) dates)

Month projections are pure data; blank grids contain row and column positions without invented dates.

Query safety

Queries are data, never Clojure forms. read-query uses clojure.edn/read-string with no tagged readers. It does not evaluate symbols or resolve functions. Applications accepting remote query text should also set a request-size limit before parsing.

Development

Run the local quality gate with clojure -T:build ci. It runs unit and generated-range property tests, clj-kondo, checks the cljdoc article manifest is present, and builds a source JAR and POM. See Getting Started, Query Language, and the other guides under doc/.

References

The library is independent of any calendar website. For background examples, see the Beta Calendars homepage and its blank calendar reference.

License

MIT. See LICENSE.