How would I go about implementing ValidBigDecimal for String?

[KaranAhlawat]

Or is there something of the sort in the library already? I mostly want to translate String Refined ValidBigDecimal from scala-refined to iron.

[KaranAhlawat]

Update: I tried writing a custom constraint, but that doesn't work because try-catch cannot be inlined. Neither can the scala.util.Try data structure. Any ideas? @Iltotore

[Iltotore]

If you want to make your constraint usable at compile-time, you will probably have to use a macro.

You can look into io.github.iltotore.iron.constraint.string for examples.

PS: thank you for the bump, I forgot about your thread 😅

[KaranAhlawat]

Thank you! I think I that was it. Here is what I came up with (and it seems to work)

  final class ValidBigDecimal

  inline given Constraint[String, ValidBigDecimal] with
    override inline def message: String = "Should be a valid decimal"

    override inline def test(value: String): Boolean =
      ${check('value)}

  private def check(expr: Expr[String])(using Quotes): Expr[Boolean] =
    expr.value match
      case Some(value) =>
        Expr(Try(BigDecimal(value)).isSuccess)
      case _ =>
        '{Try(BigDecimal($expr)).isSuccess}

[Iltotore]

Looks good to me 👍