Decoder

A decoder for Option[A].

This is modeled as a separate, named, subtype because Option decoders often have special semantics around the handling of JNull. By having this as a named subtype, we premit certain optimizations that would otherwise not be possible. See circe-generic-extras for some examples.

Helper methods for working with cats.data.StateT values that transform the ACursor.

Return an instance for a given type.

Create a decoder that always returns a single value, useful with some flatMap situations.

Construct an instance that always fails with the given DecodingFailure.

Construct an instance that always fails with the given error message.

Construct an instance from a cats.data.StateT value.

Construct an instance from a function.

This is for easier interop with code that already returns scala.util.Try. You should prefer instance for any new code.

Construct an instance from a function that may reattempt on failure.

Decode a JSON value into a scala.math.BigDecimal.

Note that decoding will fail on some very large values that could in principle be represented as BigDecimals (specifically if the scale is out of the range of scala.Int when the unscaledValue is adjusted to have no trailing zeros). These large values can, however, be round-tripped through JsonNumber, so you may wish to use decodeJsonNumber in these cases.

Also note that because scala.scalajs.js.JSON parses JSON numbers into a floating point representation, decoding a JSON number into a BigDecimal on Scala.js may lose precision.

Decode a JSON value into a scala.math.BigInt.

Note that decoding will fail if the number has a large number of digits (the limit is currently 1 << 18, or around a quarter million). Larger numbers can be decoded by mapping over a scala.math.BigDecimal, but be aware that the conversion to the integral form can be computationally expensive.

Decode a JSON value into a scala.Byte.

See decodeLong for discussion of the approach taken for integral decoding.

Decode a JSON value into a scala.Double.

Unlike the integral decoders provided here, this decoder will accept values that are too large to be represented and will return them as PositiveInfinity or NegativeInfinity, and it may lose precision.

Decode a JSON value into a scala.Float.

See decodeDouble for discussion of the approach taken for floating-point decoding.

Decode a JSON value into a scala.Int.

See decodeLong for discussion of the approach taken for integral decoding.

Decode a JSON value into a java.math.BigDecimal.

Decode a JSON value into a java.math.BigInteger.

Decode a JSON value into a java.lang.Boolean.

Decode a JSON value into a java.lang.Byte.

Decode a JSON value into a java.lang.Character.

Decode a JSON value into a java.lang.Double.

Decode a JSON value into a java.lang.Float.

Decode a JSON value into a java.lang.Integer.

Decode a JSON value into a java.lang.Long.

Decode a JSON value into a java.lang.Short.

Decode a JSON value into a scala.Long.

Decoding will fail if the value doesn't represent a whole number within the range of the target type (although it can have a decimal part: e.g. 10.0 will be successfully decoded, but 10.01 will not). If the value is a JSON string, the decoder will attempt to parse it as a number.

Decode a JSON value into a scala.Short.

See decodeLong for discussion of the approach taken for integral decoding.

Decode a Boolean whose value is known at compile time.

Decode a Char whose value is known at compile time.

Decode a Double whose value is known at compile time.

Decode a Float whose value is known at compile time.

Decode a Int whose value is known at compile time.

Decode a Long whose value is known at compile time.

Decode a String whose value is known at compile time.