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feature_comparison_bond.md

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Feature comparison between bond and refined

What bond and refined have in common

  • Additional constraints on ordinary types:

    // bond
def x: Int with GreaterThan[T.`14`.T] = ???

// refined
def x: Int @@ Greater[W.`14`.T] = ???

  • Functions to validate runtime values:

    // bond
scala> GreaterThan(14).validate(16)
res4: Result[Int with GreaterThan[Int(14)]] = Valid(16)

// refined
scala> refineT[Greater[W.`14`.T]](16)
res0: Either[String, Int @@ Greater[Int(14)]] = Right(16)

  • Weaken constraints at compile time:

    // bond
scala> val x = GreaterThan(14).validate(16).get
x: Int with net.fwbrasil.bond.GreaterThan[Int(14)] = 16

scala> GreaterThan(12).lift(x)
res6: Int with GreaterThan[Int(14)] with GreaterThan[Int(12)] = 16

scala> val y: Int with GreaterThan[T.`12`.T] = GreaterThan(12).lift(x)
y: Int with GreaterThan[Int(12)] = 16

// refined
scala> val x: Int @@ Greater[W.`14`.T] = 16
x: Int @@ Greater[Int(14)] = 16

scala> val y: Int @@ Greater[W.`12`.T] = x
y: Int @@ Greater[Int(12)] = 16

Invalid constraint transformations are compile errors in both libraries.

  • User defined constraints

What bond has but refined not

  • The Result type can accumulate validation errors in a for comprehension:

    scala> for {
     |   x <- GreaterThan(12).validate(10)
     |   y <- LesserThan(0).validate(5)
     | } yield (x, y)
res3: Result[(Int with GreaterThan[Int(12)], Int with LesserThan[Int(0)])] = Invalid(List(Violation(10,GreaterThan(12)), Violation(5,LesserThan(0))))

What refined has but bond not

  • Check if literals confirm to constraints at compile-time:

    scala> val y: Int @@ Greater[W.`12`.T] = 13
y: Int @@ Greater[Int(12)] = 13

scala> val y: Int @@ Greater[W.`12`.T] = 11
<console>:40: error: Predicate failed: (11 > 12).
       val y: Int @@ Greater[W.`12`.T] = 11
                                         ^

  • Constraints that take other contraints as parameters:

    scala> val y: Char @@ And[Letter, UpperCase] = 'R'
y: Char @@ And[Letter, UpperCase] = R