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Algebra.scala
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Algebra.scala
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/*
* Copyright 2015 Creative Scala
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package doodle
package algebra
import cats.Applicative
/** Base type for algebras that produce results in some effect type `Drawing`.
* Users of algebras should use dependent method types (or dependent function
* types in Scala 3) to return the `Drawing` type of the method they are
* passed:
*
* ```scala
* def usingAlgebra(algebra: Algebra): algebra.Drawing = ???
* ```
*
* All `Drawing` types are required to implement `Applicative`
*/
trait Algebra {
/** The effect type that methods on this algebra produce. Represents an effect
* that, when run, will draw something and produce a value.
*/
type Drawing[_]
implicit val drawingInstance: Applicative[Drawing]
}
object Algebra {
type Aux[F0[_]] = Algebra { type Drawing[A] = F0[A] }
}