open Reified
open Reified.Refinements
open Reified.Result

Walkthrough: Reference Apps

The reference apps exercise CLI, form, JSON, and storage boundaries. Two tiers are runnable:

1. Reified.ReferenceApp.Intro, plain Result, checks, refined values, and accumulated validation, with no schemas at all. Start there if you are new; this page covers the schema tier.
2. examples/Reified.ReferenceApp.Wire, boundary discipline with the wire tier generated from [<DeriveSchema>] records.

The generated-wire slice

dotnet run --project examples/Reified.ReferenceApp.Wire/Reified.ReferenceApp.Wire.fsproj --nologo

The wire slice generates schemas from ordinary records with constraint attributes:

open Reified.DerivedSchema

type Visibility =
    | Private
    | Public

[<DeriveSchema>]
type WorkspaceCard =
    { [<Min 1; Max 60>] Name: string
      [<Email; SchemaName "owner_email">] OwnerEmail: string
      [<Default "private">] Visibility: Visibility
      [<Distinct>] Members: string list }

    // Called by the generated schema instead of a record literal.
    [<SchemaConstructor>]
    static member create name (ownerEmail: string) visibility members =
        { Name = name; OwnerEmail = ownerEmail.ToLowerInvariant(); Visibility = visibility; Members = members }

schemagen writes the sibling workspace.g.fs: the schema pipeline you would have written by hand — schema, parse, and validate — and, because WorkspaceCardV1/WorkspaceCard follow the version-chain naming convention, a WorkspaceCard.contract builder that takes your typed v1 → v2 migration. No Fields module is generated; the wire records are yours, and the generated code refers to them. You write the migration, the strict domain mapping (TrustedCard rejects an owner listed as a member, a rule the wire deliberately cannot express), and a head-version write through a compiled codec.

The constraint attributes stay on the wire records, so input is admitted through Contract.parse — which runs Schema.parse on the selected frozen schema and therefore enforces Min/Max/Email/Distinct. The compiled codec is used only to write an already-admitted head-version value, not to decode untrusted input. That is the difference from the permissive-DTO strategy in Schema or Generated DTO: this app wants the wire rules enforced at the boundary, so it reads with the boundary parser rather than the trusted decoder. Generated schemas work with JsonSchema.generate and Json.compile.

See Generated version series for the version-series attribute vocabulary and Build Generation for running generation in your build with Reified.SchemaGen.MSBuild.