org.llm4s.schema.iron

The uPickle ReadWriter of A :| C: A's, refined after reading. A value that breaks the constraint fails to read with the constraint's message, so completeStructured, completeStructuredOf and Tool.of return a Left naming the field and the bound rather than a value the type should have rejected.

Iron's own iron-upickle module defines the same instance: import one of the two, not both, or the instances are ambiguous.

The schema of an Iron refinement type, A :| C: the schema of A with C written into it as JSON Schema bounds, so the model is told the bound it must keep.

import io.github.iltotore.iron.*
import io.github.iltotore.iron.constraint.all.*
import org.llm4s.schema.*
import org.llm4s.schema.iron.given

case class Review(
 @description("Short headline") title: String :| (Not[Blank] & MaxLength[80]),
 @description("Stars") rating: Int :| Interval.Closed[1, 5]
) derives SchemaOf, ReadWriter

Described:

• on Int, Long, Double and Float: Greater, GreaterEqual, Less, LessEqual, StrictEqual, Positive, Positive0, Negative, Negative0 and every Interval, as minimum and maximum (and, on Double and Float, exclusiveMinimum and exclusiveMaximum). An integer's exclusive bound is written as the inclusive one it equals (Greater[0] as minimum: 1), which every provider accepts.
• on String: MinLength, MaxLength, FixedLength, Not[Empty] and Not[Blank], as minLength and maxLength. Not[Blank] is described as minLength: 1, which every non-blank string meets; that the string must not be only whitespace is checked when the reply is read.
• on List, Seq, Vector and Set: MinLength, MaxLength, FixedLength and Not[Empty], as minItems and maxItems.
• a conjunction C1 & C2 of these, as both bounds; two bounds of one kind keep the tighter.

Any other constraint, Match among them (core's StringSchema has no pattern yet), and a constraint on any other type, is refused at compile time with a message naming it, rather than left out of the schema without a word.

The bounds are written into the schema A's own SchemaOf builds, so the field keeps its description, and an Option[A :| C], a List[A :| C] or a case class holding one is derived as usual.