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rose-ash/lib/persist/query.sx
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persist: read-side query helpers — seq/time/type/predicate scans + 9 tests
query.sx: read-between (seq range), read-since/read-window (by :at),
read-by-type, read-where, count-where. Pure scans over persist/read for audit
windows, type filters, since-cursors. 152/152.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-06 19:22:03 +00:00

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; persist/query — read-side helpers over a stream: slice by seq range, filter by
; timestamp / type / predicate. Pure reads composed from persist/read, no
; backend changes. The log is bad at ad-hoc relational queries (project into a
; kv read model for those) but these cover the common log scans: an audit window
; by time, a type filter, a since-cursor for incremental consumers.
; Requires: lib/persist/log.sx.
; events with seq in [from, to] inclusive
(define
persist/read-between
(fn
(b stream from to)
(filter
(fn
(e)
(and (>= (persist/event-seq e) from) (<= (persist/event-seq e) to)))
(persist/read b stream))))
; events at or after a timestamp (events carry :at; never a clock here)
(define
persist/read-since
(fn
(b stream at)
(filter (fn (e) (>= (persist/event-at e) at)) (persist/read b stream))))
; events whose :at is in [from, to] inclusive — an audit window
(define
persist/read-window
(fn
(b stream from to)
(filter
(fn
(e)
(and (>= (persist/event-at e) from) (<= (persist/event-at e) to)))
(persist/read b stream))))
; events matching a predicate (e -> truthy)
(define
persist/read-where
(fn (b stream pred) (filter pred (persist/read b stream))))
; events of a given type
(define
persist/read-by-type
(fn
(b stream type)
(filter
(fn (e) (equal? (persist/event-type e) type))
(persist/read b stream))))
; count events matching a predicate
(define
persist/count-where
(fn (b stream pred) (len (persist/read-where b stream pred))))