formualizer-eval

Arrow-backed Excel formula engine with dependency graph and incremental recalculation.

formualizer-eval is the calculation core of Formualizer. It takes ASTs from formualizer-parse, tracks dependencies between cells, and evaluates 320+ Excel-compatible functions with incremental recomputation and optional parallel execution.

When to use this crate

Use formualizer-eval when you want full control over the evaluation engine:

• You have your own cell storage and want to plug in Formualizer's evaluator
• You need custom resolvers, function providers, or evaluation observers
• You're building a spreadsheet product with custom data models

For most integrations, formualizer-workbook is easier — it wraps this engine with ergonomic workbook APIs and handles storage for you.

Features

• Apache Arrow storage — columnar sheet backing with spill overlays for efficient large-workbook evaluation.
• Dependency graph — incremental graph with cycle detection, topological scheduling, and CSR (Compressed Sparse Row) edge format.
• 320+ built-in functions — math, text, lookup (XLOOKUP, VLOOKUP, HLOOKUP), date/time, financial, statistics, database, engineering.
• Dynamic arrays — FILTER, UNIQUE, SORT, SORTBY with automatic spill semantics.
• Parallel evaluation — optional multi-threaded evaluation via Rayon with configurable thread pools.
• Deterministic mode — inject clock, timezone, and RNG seed for reproducible results.
• Extensible — Resolver, RangeResolver, and FunctionProvider traits for custom implementations.
• Warm-up planning — pre-compute evaluation strategy for large workbooks.

Quick start

use formualizer_common::LiteralValue;
use formualizer_eval::engine::{Engine, EvalConfig};
use formualizer_eval::test_workbook::TestWorkbook;

let resolver = TestWorkbook::new()
    .with_cell_a1("Sheet1", "A1", LiteralValue::Number(2.0))
    .with_cell_a1("Sheet1", "A2", LiteralValue::Number(3.0));

let mut engine = Engine::new(resolver, EvalConfig::default());
// Insert formulas, build dependency graph, and evaluate

License

Dual-licensed under MIT or Apache-2.0, at your option.