Version Matrix

Robots

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Overview

Robots is a small Scala library which aims to provide helpful utilities for validating data using the type classes and data types provided by the Cats library.

Getting Started

Add the following to your build.sbt:

libraryDependencies += "io.github.davidgregory084" %% "robots" % "0.1.0"

Example

import robots.Validator, Validator._
import cats.data.Validated
import cats.instances.either._
import cats.instances.list._
import cats.instances.int._

case class Document(maxColumn: Int, maxLines: Int, lines: List[String])

val passing = Document(80, 120, List("Hello", "World"))
val failing = Document(4, 1, List("Hey", "World"))

val documentValidator =
  validate[List, String, Document].
    has(_.maxColumn)(gt(0, List("Max width should be greater than zero"))).
    has(_.maxLines)(gt(0, List("Max line count should be greater than zero"))).
    has2(_.maxLines, _.lines)(Validator {
      case (maxLines, lines) =>
        if (lines.length <= maxLines)
          Nil
        else
          List("Exceeded the maximum number of lines")
    }).
    all2(_.maxColumn, _.lines)(Validator {
      case (maxColumn, line) =>
        if (line.length <= maxColumn)
          Nil
        else
          List("Exceeded the maximum number of columns")
    })
// Works well with `Either` and `Validated`
documentValidator.runNel[Validated](passing)
// res4: cats.data.Validated[cats.data.NonEmptyList[String],Document] = Valid(Document(80,120,List(Hello, World)))

documentValidator.runNel[Validated](failing)
// res5: cats.data.Validated[cats.data.NonEmptyList[String],Document] = Invalid(NonEmptyList(Exceeded the maximum number of lines, Exceeded the maximum number of columns))

documentValidator.runNel[Either](passing)
// res6: Either[cats.data.NonEmptyList[String],Document] = Right(Document(80,120,List(Hello, World)))

documentValidator.runNel[Either](failing)
// res7: Either[cats.data.NonEmptyList[String],Document] = Left(NonEmptyList(Exceeded the maximum number of lines, Exceeded the maximum number of columns))

// You can brjng any `MonadError`
import cats.data.Ior
// import cats.data.Ior

documentValidator.run[Ior[List[String], ?]](passing)
// res9: cats.data.Ior[List[String],Document] = Right(Document(80,120,List(Hello, World)))

documentValidator.run[Ior[List[String], ?]](failing)
// res10: cats.data.Ior[List[String],Document] = Left(List(Exceeded the maximum number of lines, Exceeded the maximum number of columns))

// Even ones that discard errors
import cats.instances.option._
// import cats.instances.option._

documentValidator.run_[Option](passing)
// res12: Option[Document] = Some(Document(80,120,List(Hello, World)))

documentValidator.run_[Option](failing)
// res13: Option[Document] = None

Conduct

Contributors are expected to follow the Typelevel Code of Conduct while participating on Github and any other venues associated with the project.

Acknowledgements

Thanks to Dave Gurnell (@davegurnell) and Brendan Maginnis (@brendanator) for the design which inspired this library.

License

All code in this repository is licensed under the Apache License, Version 2.0. See LICENSE.