rechentafel

CircleCI Clojars Slack

A pure-Clojure spreadsheet interpreter. Parses Excel formulas, builds a per-cell dependency graph, and evaluates workbooks — no Apache POI, no LibreOffice, no native deps at runtime.

Works in Clojure and ClojureScript (.cljc throughout except for the optional POI loader).

;; deps.edn
{:deps
 {org.replikativ/rechentafel {:mvn/version "0.1.X"}}} ;; latest on Clojars

Runtime deps:

• org.clojure/clojure 1.12+
• com.widdindustries/cljc.java-time (used by the datetime functions on both runtimes — backed by java.time on the JVM and @js-joda/core on cljs).

POI / XLSX I/O is optional — see Loading .xlsx files.

(require '[rechentafel.eval :as e]
 '[rechentafel.cell :as c]
 'rechentafel.functions.all) ;; registers the built-in function pack
(def wb (-> (e/empty-workbook ["Sheet1"])
 (e/set-cell (c/pack 0 0 0) 10) ;; A1 = 10
 (e/set-cell (c/pack 0 0 1) 20) ;; B1 = 20
 (e/set-cell (c/pack 0 0 2) "=A1+B1") ;; C1 = A1+B1
 (e/recalc)))
(e/get-cell wb (c/pack 0 0 2))
;;=> {:t :num :v 30.0}

Cell addresses are packed into a long via (c/pack sheet row col) — all 0-indexed. Values come back as tagged maps ({:t :num/:str/:bool/:err :v ...}).

Updates are incremental: set-cell marks the cell and its transitive dependents dirty; recalc topologically re-evaluates only the dirty set and writes results back into the sheet store.

The interpreter doesn't parse XLSX on its own. The optional rechentafel.poi namespace is a ~80-line wrapper around Apache POI that replays each cell into a spread workbook:

;; deps.edn: add -A:poi or include POI directly
(require '[rechentafel.poi :as poi])
(def wb (poi/load-workbook "model.xlsx"))
;; cells are parsed and recalculated by our interpreter — POI's cached
;; values are ignored.

POI is on the classpath only under the :poi (or :dev) alias, so the library itself stays pure.

 set-cell / edits
 │
 ▼
 parser.cljc ──► ast (rc-normalized)
 │
 ▼
 eval.cljc ──► dep graph (per-cell reads / volatile / dirty sets)
 │
 ▼
 mtv.cljc ──► multi-typed column sheet store
 │
 ▼
 functions/ ──► pluggable registry (math, stats, text, lookup,
 all.cljc financial, datetime, logical, database,
 engineering, info, misc)

Key modules:

Roughly 270 functions registered by rechentafel.functions.all:

• Math / trig — arithmetic, logs, powers, full trig + hyperbolic + inverse trig, reciprocal trig (COT/SEC/CSC + hyperbolic + inverse), PHI, GAUSS, rounding family
• Stats — mean/median/mode, variance/stdev, NORM/T/F/CHI/BINOM/POISSON distributions + inverses, rank, percentile, correlation, regression
• Text — LEN/FIND/SEARCH/LEFT/RIGHT/MID/SUBSTITUTE/REPLACE/TEXTJOIN, TEXT/VALUE/NUMBERVALUE, UNICODE/UNICHAR, TEXTBEFORE/TEXTAFTER
• Lookup — VLOOKUP/HLOOKUP/XLOOKUP/XMATCH/INDEX/MATCH/OFFSET/INDIRECT/ CHOOSE
• Logical — IF/IFS/SWITCH/AND/OR/NOT/XOR/IFERROR/IFNA
• Datetime — DATE/TIME/YEAR/MONTH/DAY/HOUR/MINUTE/SECOND/WEEKDAY/ ISOWEEKNUM/EDATE/EOMONTH/DAYS/DATEDIF/DATEVALUE/NETWORKDAYS/YEARFRAC
• Financial — PV/FV/PMT/NPER/RATE/NPV/IRR/XIRR/XNPV/CUMIPMT/CUMPRINC/ SLN/SYD/DB/EFFECT/NOMINAL/ISPMT
• Engineering — bit ops (AND/OR/XOR/LSHIFT/RSHIFT), BIN2DEC family, CONVERT, ERF, BESSEL, complex numbers
• Info — CELL/INFO/SHEET/SHEETS/ISFORMULA + full IS* predicates
• Aggregates — SUMIF/COUNTIF/AVERAGEIF + multi-criterion variants, SUMPRODUCT, SUBTOTAL, AGGREGATE
• Matrix — MMULT/MINVERSE/TRANSPOSE/SUMXMY2
• Database — DSUM/DCOUNT/DAVERAGE/DMAX/DMIN/...

bin/run-unittests # pure JVM tests (clojure -M:test)
bin/run-cljstests # cljs tests under Node (needs `npm install` first)
clj -M:poi-oracle # POI parity oracle (opt-in, pulls POI deps)

The oracle suite builds each formula under test both in our engine and in POI, then diffs results — cross-validates Excel semantics.

clj -M:bench -m rechentafel.bench.main # all shapes, JVM
npx shadow-cljs release node-bench && \
 node out/node-bench.js # all shapes, cljs
clj -M:bench -m rechentafel.bench.compare # vs LibreOffice + POI

Numbers and methodology in .internal/bench-results.md. On 10k-cell shapes the engine is in the same ballpark as Apache POI and ×ばつ faster than LibreOffice headless.

Excel 365 feature coverage including LET / LAMBDA / dynamic arrays / 3D refs / structured table refs / FORMULATEXT. Cross-runtime correctness verified against LibreOffice and POI on the benchmark fixtures (test/rechentafel/golden_test.cljc).