gapt.proofs.context.update.Definition.scala Maven / Gradle / Ivy

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General Architecture for Proof Theory

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package gapt.proofs.context.update

import gapt.expr.Const
import gapt.expr.Expr
import gapt.expr.ty.TVar
import gapt.expr.util.freeVariables
import gapt.expr.util.typeVariables
import gapt.proofs.context.Context
import gapt.proofs.context.State
import gapt.proofs.context.facet.Constants
import gapt.proofs.context.facet.Definitions
import gapt.proofs.context.facet.Reductions

case class Definition(what: Const, by: Expr) extends Update {
  val Const(name, ty, ps) = what
  require(ps.forall(_.isInstanceOf[TVar]), s"type parameters $ps must be variables")
  require(ty == by.ty, s"type $ty of $what and type ${by.ty} of $by must match!")
  require(freeVariables(by).isEmpty, s"$this: contains free variables ${freeVariables(by)}")
  require(typeVariables(by).toSet subsetOf ps.toSet)
  require(typeVariables(what).toSet subsetOf ps.toSet)

  def toTuple: (Const, Expr) = (what, by)

  override def apply(ctx: Context): State = {
    ctx.check(what.ty)
    ctx.check(by)
    ctx.state.update[Constants](_ + what)
      .update[Definitions](_ + this)
      .update[Reductions](_ + (what -> by))
  }
}
object Definition {
  implicit def apply(pair: (Const, Expr)): Definition =
    Definition(pair._1, pair._2)
}