Xantham

A schema-driven TypeScript → F# bindings generator.

Xantham is a hard fork of Glutinum that tackles the TypeScript-to-.NET bindings problem differently. Instead of a single end-to-end pipeline it separates concerns into extract, encode/decode, and generate phases across Fable and .NET boundaries. The common JSON schema is the only hand-off point; generators consume Xantham.Decoder and never touch the extraction layer.

Glutinum vs Xantham

Both tools read .d.ts files and emit F# bindings. They make different trade-offs.

	Glutinum	Xantham
Try it now	Web playground — browser, no install	CLI only — requires Node.js + .NET SDK
Setup	Zero	Moderate
Input scope	One `.d.ts` entry point	Entire type graph, recursively across all referenced files
Import statements	Not generated — wired by hand	Generated automatically; provenance is tracked through the full type tree
Output style	Single built-in format	User-defined — bring your own strategy (string concat, Fabulous.AST, SyntaxOak, …)
Encoder replaceability	N/A — monolithic	TSC can be swapped (e.g. TSGO) without touching decoders or generators
Decoder reuse	N/A	Any consumer takes a dependency on `Xantham.Decoder` independently
Complexity	Low	Higher — three distinct phases

Choose Glutinum when you need a quick answer for a single file and want zero friction.

Choose Xantham when you need the full picture: multi-file type graphs, generated imports, and control over how the output looks.

How It Works

Glutinum

flowchart LR A[.d.ts Input] --> B[TypeScript Compiler API] subgraph Fable / Glutinum B --> C[GlueAST] C --> D[FSharpAST] D --> E[String Concatenation] end E --> F[F# Bindings]

Xantham

flowchart LR input[".d.ts entry point"] --> tsc subgraph Fable / Xantham.Fable tsc["TypeScript Compiler API"] crawler["Recursive AST Crawler"] thoth_enc["Thoth Encoder"] tsc --> crawler crawler --> thoth_enc end subgraph Common schema["JSON Schema"] end subgraph .NET / Xantham.Decoder thoth_dec["Thoth Decoder"] util["Utility Layer"] thoth_dec --> util end subgraph Userland Generators gen1["Xantham.SimpleGenerator — Fabulous.AST"] gen2["Your Generator — String Concat / SyntaxOak / …"] end schema -.-> thoth_enc schema -.-> thoth_dec thoth_enc --> json["JSON"] json --> thoth_dec util --> types["F# Types"] types --> gen1 types --> gen2 gen1 --> out["F# Bindings"] gen2 --> out

Xantham's extractor follows every type reference recursively. By the time the decoder receives the schema it has the complete type graph — all the information needed to resolve cross-file references and emit accurate open / import statements.

Modules

Module	Role
Xantham.Common	Shared discriminated union schema (`Common.Types.fs`) — the contract between extractor and generators. Included directly as a source file in both `Xantham.Fable` and `Xantham.Decoder`; not a separate assembly.
Xantham.Fable	TypeScript extractor compiled to JS via Fable. Crawls `.d.ts` files via ts-morph, merges overloads by `TypeKey`, and emits JSON conforming to the common schema.
Xantham.Fable.Core	Minimal Fable bindings stub. Provides F# representations of TypeScript type-system idioms (`keyof`, indexed access types, heterogeneous property unions).
Xantham.Decoder	.NET library. Decodes the JSON schema into strongly-typed F# structures and provides a utility layer for generator consumption.
Xantham.Generator	Core rendering library — path system, type-ref model, and F# AST helpers.

Current Status

Component	Status	Notes
Schema (`Xantham.Common`)	🟡 RC	Near-stable; breaking changes require coordinated updates across all layers.
Reader (`Xantham.Fable`)	🟡 RC	Handles large hierarchies (e.g. solid-js). Stack-based traversal avoids JS stack overflows.
Decoder (`Xantham.Decoder`)	🟡 RC	Review documentation and testing.
Generator (`Xantham.Generator`)	🟠 In progress	Structural output works.