A typesafe F# DSL for building Excel workbooks, interpreted into calls against the DocumentFormat.OpenXml SDK directly — the DSL is a plain data model (records/DUs with structural equality), a Writer compiles it to OOXML, and a Reader parses an existing .xlsx back into the same DSL.

Most Excel libraries only go one direction: build from scratch, or mutate an existing file, through an imperative API. This one round-trips — Workbook.load reads a real .xlsx/.xlsm back into the DSL, and Workbook.generateScript goes a step further, rendering that model back out as runnable F# (or C#, via the companion wrapper) source that rebuilds an equivalent file — a decompiler for spreadsheets, not just a writer. Xml.ofWorkbook/Json.ofWorkbook do the same translation to plain XML or JSON against a real schema, useful for feeding an .xlsx from a transform pipeline (e.g. XSLT) with no code at all, or for diffing spreadsheets in version control.

Covers cells, styles, formulas, conditional formatting, data validation, tables, charts, images, pivot tables, sparklines, and VBA macro embedding.

Quick start

open Kookerella.FsOpenXmlDsl
open type Kookerella.FsOpenXmlDsl.SheetDsl

let headerStyle =
    { CellStyle.Default with
        Font = Some { FontStyle.Default with Bold = true }
        Fill = Some { Color = Rgb(220uy, 220uy, 220uy) } }

let data =
    sheet
        "Sheet1"
        [ row [ cell (Text "Name", style = headerStyle)
                cell (Text "Amount", style = headerStyle) ]
          row [ cell (Text "Widgets")
                cell (Number 42.5, style = { CellStyle.Default with NumberFormat = Some TwoDecimal }) ]
          Freeze(1, 0) ]

workbook [ data ] |> Workbook.save "out.xlsx"

// Reverse transform:
let roundTripped = Workbook.load "out.xlsx"

Install

dotnet add package Kookerella.FsOpenXmlDsl

License

MIT licensed.

See the GitHub repository for the full feature list, the C# wrapper, and the MCP server built on top of this.