A1/B2 addressed cell grid with letter columns (A, Z, AA, AB, ...).
Cell values: number, text, boolean, error (#DIV/0!, #REF!, #CYCLE!, #NAME?, #NUM!, #VALUE!) and formula.
Formula language: =A1+B2*3, parentheses, operators (+ - * / ^ %, comparisons, &), literals, cell references, ranges (A1:C3) and function calls. A hand-written lexer feeds a recursive descent parser that builds an AST.
Around 38 built-in functions: SUM, PRODUCT, AVERAGE/AVG, MIN, MAX, COUNT, COUNTA, ABS, SQRT, POWER, MOD, ROUND, TRUNC, INT, SIGN, FLOOR, CEIL/CEILING, IF, AND, OR, NOT, TRUE, FALSE, IFERROR, ISERROR, ISBLANK, ISNUMBER, ISTEXT, CONCAT/CONCATENATE, LEN, LEFT, RIGHT, MID, UPPER, LOWER, TRIM, REPT, EXACT, VALUE, INDEX.
Dependency graph: every formula records the cells it references; a change recomputes only the affected dependents (dirty propagation) in topological order (Kahn). Circular references resolve to #CYCLE! instead of looping.
CSV import and export (RFC4180 quoting), for both computed values and raw formulas.

Library

import 'package:cellar/cellar.dart';

final sheet = Sheet();
sheet.setValue('A1', '10');
sheet.setValue('A2', '20');
sheet.setValue('B1', '=SUM(A1:A2)');
print(sheet.valueOf('B1').display()); // 30

CLI

dart run cellar <file.csv> [options]

  --set REF=CONTENT   Set a cell before printing (formula keeps its '=', e.g. --set B1==A1+1)
  --show REF          Print the value and raw content of a cell
  --formulas          Print the raw formulas grid
  --csv-values        Emit the computed sheet as CSV
  --csv-formulas      Emit the formulas sheet as CSV

Example:

dart run cellar example/invoice.csv
dart run cellar example/invoice.csv --set B2=10 --show D7

Tests

dart analyze
dart test