Codec

Companion object Codec

trait Codec[A] extends GenCodec[A, A]

Supports encoding a value of type A to a BitVector and decoding a BitVector to a value of A.

Not every value of A can be encoded to a bit vector and similarly, not every bit vector can be decoded to a value of type A. Hence, both encode and decode return either an error or the result. Furthermore, decode returns the remaining bits in the bit vector that it did not use in decoding.

There are various ways to create instances of Codec. The trait can be implemented directly or one of the constructor methods in the companion can be used (e.g., apply). Most of the methods on Codec create return a new codec that has been transformed in some way. For example, the xmap method converts a Codec[A] to a Codec[B] given two functions, A => B and B => A.

One of the simplest transformation methods is def withContext(context: String): Codec[A], which pushes the specified context string in to any errors (i.e., Errs) returned from encode or decode.

See the methods on this trait for additional transformation types.

See the codecs package object for pre-defined codecs for many common data types and combinators for building larger codecs out of smaller ones.

Tuple Codecs

The ~ operator supports combining a Codec[A] and a Codec[B] in to a Codec[(A, B)].

For example:

val codec: Codec[Int ~ Int ~ Int] = uint8 ~ uint8 ~ uint8

Codecs generated with ~ result in left nested tuples. These left nested tuples can be pulled back apart by pattern matching with ~. For example:

Codec.decode(uint8 ~ uint8 ~ uint8, bytes) map { case a ~ b ~ c => a + b + c }

Alternatively, a function of N arguments can be lifted to a function of left-nested tuples. For example:

val add3 = (_: Int) + (_: Int) + (_: Int)
Codec.decode(uint8 ~ uint8 ~ uint8, bytes) map add3

Similarly, a left nested tuple can be created with the ~ operator. This is useful when creating the tuple structure to pass to encode. For example:

(uint8 ~ uint8 ~ uint8).encode(1 ~ 2 ~ 3)

Tuple based codecs are of limited use compared to HList based codecs, which is discussed later.

Note: this design is heavily based on Scala's parser combinator library and the syntax it provides.

flatZip

Sometimes when combining codecs, a latter codec depends on a formerly decoded value. The flatZip method is important in these types of situations -- it represents a dependency between the left hand side and right hand side. Its signature is def flatZip[B](f: A => Codec[B]): Codec[(A, B)]. This is similar to flatMap except the return type is Codec[(A, B)] instead of Decoder[B].

Consider a binary format of an 8-bit unsigned integer indicating the number of bytes following it. To implement this with flatZip, we could write:

val x: Codec[(Int, ByteVector)] = uint8 flatZip { numBytes => bytes(numBytes) }
val y: Codec[ByteVector] = x.xmap[ByteVector]({ case (_, bv) => bv }, bv => (bv.size, bv))

In this example, x is a Codec[(Int, ByteVector)] but we do not need the size directly in the model because it is redundant with the size stored in the ByteVector. Hence, we remove the Int by xmap-ping over x. The notion of removing redundant data from models comes up frequently. Note: there is a combinator that expresses this pattern more succinctly -- variableSizeBytes(uint8, bytes).

HList Codecs

HLists are similar to tuples in that they represent the product of an arbitrary number of types. That is, the size of an HList is known at compile time and the type of each element is also known at compile time. For more information on HLists in general, see Shapeless.

Codec makes heavy use of HLists. The primary operation is extending a Codec[L] for some L <: HList to a Codec[A :: L]. For example:

val uint8: Codec[Int] = ...
val string: Codec[String] = ...
val codec: Codec[Int :: Int :: String] = uint8 :: uint8 :: string

The :: method is sort of like cons-ing on to the HList but it is doing so *inside* the Codec type. The resulting codec encodes values by passing each component of the HList to the corresponding codec and concatenating all of the results.

There are various methods on this trait that only work on Codec[L] for some L <: HList. Besides the aforementioned :: method, there are others like :::, flatPrepend, flatConcat, etc. One particularly useful method is dropUnits, which removes any Unit values from the HList.

Given a Codec[X0 :: X1 :: ... Xn :: HNil] and a case class with types X0 to Xn in the same order, the HList codec can be turned in to a case class codec via the as method. For example:

case class Point(x: Int, y: Int, z: Int)
val threeInts: Codec[Int :: Int :: Int :: HNil] = uint8 :: uint8 :: uint8
val point: Codec[Point] = threeInts.as[Point]

flatPrepend

The HList analog to flatZip is flatPrepend. It has the signature:

def flatPrepend[L <: HList](f: A => Codec[L]): Codec[A :: L]

It forms a codec of A consed on to L when called on a Codec[A] and passed a function A => Codec[L]. Note that the specified function must return an HList based codec. Implementing our example from earlier using flatPrepend:

val x: Codec[Int :: ByteVector :: HNil] = uint8 flatPrepend { numBytes => bytes(numBytes).hlist }

In this example, bytes(numBytes) returns a Codec[ByteVector] so we called .hlist on it to lift it in to a Codec[ByteVector :: HNil].

There are similar methods for flat appending and flat concating.

Coproduct Codecs

Given some ordered list of types, potentially with duplicates, a value of the HList of those types has a value for *every* type in the list. In other words, an HList represents having an X0 AND X1 AND ... AND XN. A Coproduct for the same list of types represents having a value for *one* of those types. In other words, a Coproduct represents having an X0 OR X1 OR ... OR XN. This is somewhat imprecise because a coproduct can tell us exactly which Xi we have, even in the presence of duplicate types.

A coproduct can also be thought of as an Either that has an unlimited number of choices instead of just 2 choices.

Shapeless represents coproducts in a similar way as HLists. A coproduct type is built using the :+: operator with a sentinal value of CNil. For example, an Int or Long or String is represented as the coproduct type:

Int :+: Long :+: String :+: CNil

For more information on coproducts in general, see Shapeless.

Like HList based codecs, scodec supports Coproduct based codecs by coopting syntax from Shapeless. Specifically, the :+: operator is used:

val builder = uint8 :+: int64 :+: utf8

Unlike HList based codecs, the result of :+: is not a codec but rather a codecs.CoproductCodecBuilder. Having a list of types and a codec for each is not sufficient to build a coproduct codec. We also need to describe how each entry in the coproduct is differentiated from the other entries. There are a number of ways to do this and each way changes the binary format significantly. See the docs on CoproductCodecBuilder for details.

Derived Codecs

Codecs for case classes and sealed class hierarchies can often be automatically derived.

Consider this example:

import scodec.codecs.implicits._
case class Point(x: Int, y: Int, z: Int)
Codec[Point].encode(Point(1, 2, 3))

In this example, no explicit codec was defined for Point yet Codec[Point] successfully created one. It did this by "reflecting" over the structure of Point and looking up a codec for each component type (note: no runtime reflection is performed - rather, this is implemented using macro-based compile time reflection). In this case, there are three components, each of type Int, so the compiler first looked for an implicit Codec[Int]. It then combined each Codec[Int] using an HList based codec and finally converted the HList codec to a Codec[Point]. It found the implicit Codec[Int] instances due to the import of scodec.codecs.implicits._. Furthermore, if there was an error encoding or decoding a field, the field name (i.e., x, y, or z) is included as context on the Err returned.

This works similarly for sealed class hierarchies -- each subtype is internally represented as a member of a coproduct. There must be the following implicits in scope however:

Discriminated[A, D] for some discriminator type D, which provides the Codec[D] to use for encoding/decoding the discriminator
Discriminator[A, X, D] for each subtype X of A, which provides the discriminator value for type X
Codec[X] for each subtype X of A

Full examples are available in the test directory of this project.

Implicit Codecs

If authoring combinators that require implicit codec arguments, use shapeless.Lazy[Codec[A]] instead of Codec[A]. This prevents the occurrence of diverging implicit expansion errors.

Self Type: Codec[A]
Source: Codec.scala

Linear Supertypes

GenCodec[A, A], Decoder[A], Encoder[A], AnyRef, Any

Known Subclasses

DiscriminatorCodec, Tuple10Codec, Tuple11Codec, Tuple12Codec, Tuple3Codec, Tuple4Codec, Tuple5Codec, Tuple6Codec, Tuple7Codec, Tuple8Codec, Tuple9Codec, TupleCodec

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Inherited

Codec
GenCodec
Decoder
Encoder
AnyRef
Any

Implicitly

by Tuple2CodecSupport
by EnrichedCoproductDecoder
by EnrichedCoproductEncoder
by ValueCodecEnrichedWithGenericSupport
by ValueCodecEnrichedWithHListSupport
by HListCodecEnrichedWithHListSupport
by TransformSyntax
by any2stringadd
by StringFormat
by Ensuring
by ArrowAssoc

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Abstract Value Members

abstract def decode(bits: BitVector): Attempt[DecodeResult[A]]
Attempts to decode a value of type A from the specified bit vector.
Attempts to decode a value of type A from the specified bit vector.
bits
bits to decode
returns
error if value could not be decoded or the remaining bits and the decoded value

Definition Classes
Decoder
abstract def encode(value: A): Attempt[BitVector]
Attempts to encode the specified value in to a bit vector.
Attempts to encode the specified value in to a bit vector.
value
value to encode
returns
error or binary encoding of the value

Definition Classes
Encoder
abstract def sizeBound: SizeBound
Provides a bound on the size of successfully encoded values.
Provides a bound on the size of successfully encoded values.

Definition Classes
Encoder

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
def +(other: String): String

Implicit
This member is added by an implicit conversion from Codec[A] to any2stringadd[Codec[A]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
def ->[B](y: B): (Codec[A], B)

Implicit
This member is added by an implicit conversion from Codec[A] to ArrowAssoc[Codec[A]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()
def :+[B, LB <: HList](codec: Codec[B])(implicit prepend: shapeless.ops.hlist.Prepend.Aux[A, ::[B, HNil], LB], init: Aux[LB, A], last: Aux[LB, B]): Codec[LB]
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList L followed by a B.
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList L followed by a B. That is, this operator is a codec-level HList append operation.

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def :+:[B](left: Codec[B]): CoproductCodecBuilder[:+:[B, :+:[A, CNil]], ::[Codec[B], ::[Codec[A], HNil]], :+:[B, :+:[A, CNil]]]
Supports creation of a coproduct codec.
Supports creation of a coproduct codec. See scodec.codecs.CoproductCodecBuilder for details.
def ::[B](codecB: Codec[B]): Codec[::[B, ::[A, HNil]]]
When called on a Codec[A] where A is not a subytpe of HList, creates a new codec that encodes/decodes an HList of B :: A :: HNil.
When called on a Codec[A] where A is not a subytpe of HList, creates a new codec that encodes/decodes an HList of B :: A :: HNil. For example,
```
uint8 :: utf8
```
has type Codec[Int :: String :: HNil]. uint8 :: utf8 }}}
Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithHListSupport[A] performed by method ValueCodecEnrichedWithHListSupport in scodec.
Definition Classes
ValueCodecEnrichedWithHListSupport
def ::[B](codec: Codec[B]): Codec[::[B, A]]
When called on a Codec[L] for some L <: HList, returns a new codec representing Codec[B :: L].
When called on a Codec[L] for some L <: HList, returns a new codec representing Codec[B :: L]. That is, this operator is a codec-level HList prepend operation.
codec
codec to prepend

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def :::[K <: HList, KL <: HList, KLen <: Nat](k: Codec[K])(implicit prepend: shapeless.ops.hlist.Prepend.Aux[K, A, KL], lengthK: Aux[K, KLen], split: Aux[KL, KLen, K, A]): Codec[KL]
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList K followed by the HList L.
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList K followed by the HList L.

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def :~>:[B](codecB: Codec[B])(implicit ev: =:=[Unit, B]): Codec[::[A, HNil]]
When called on a Codec[A], returns a new codec that encodes/decodes B :: A :: HNil.
When called on a Codec[A], returns a new codec that encodes/decodes B :: A :: HNil. HList equivalent of ~>.

Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithHListSupport[A] performed by method ValueCodecEnrichedWithHListSupport in scodec.
Definition Classes
ValueCodecEnrichedWithHListSupport
def :~>:[B](codec: Codec[B])(implicit ev: =:=[Unit, B]): Codec[A]
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes B :: L but only returns L.
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes B :: L but only returns L. HList equivalent of ~>.

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
final def <~[B](codecB: Codec[B])(implicit ev: =:=[Unit, B]): Codec[A]
Assuming B is Unit, creates a Codec[A] that: encodes the A followed by a unit; decodes an A followed by a unit and discards the decoded unit.
Assuming B is Unit, creates a Codec[A] that: encodes the A followed by a unit; decodes an A followed by a unit and discards the decoded unit.
Operator alias of dropRight.
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def >>:~[L <: HList](f: (A) ⇒ Codec[L]): Codec[::[A, L]]
Creates a new codec that encodes/decodes an HList type of A :: L given a function A => Codec[L].
Creates a new codec that encodes/decodes an HList type of A :: L given a function A => Codec[L]. This allows later parts of an HList codec to be dependent on earlier values. Operator alias for flatPrepend.

Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithHListSupport[A] performed by method ValueCodecEnrichedWithHListSupport in scodec.
Definition Classes
ValueCodecEnrichedWithHListSupport
final def >>~[B](f: (A) ⇒ Codec[B]): Codec[(A, B)]
Returns a new codec that encodes/decodes a value of type (A, B) where the codec of B is dependent on A.
Returns a new codec that encodes/decodes a value of type (A, B) where the codec of B is dependent on A. Operator alias for flatZip.
def as[B](implicit as: Transformer[A, B]): Codec[B]
Transforms using implicitly available evidence that such a transformation is possible.
Transforms using implicitly available evidence that such a transformation is possible.
Typical transformations include converting:
- an F[L] for some L <: HList to/from an F[CC] for some case class CC, where the types in the case class are aligned with the types in L
- an F[C] for some C <: Coproduct to/from an F[SC] for some sealed class SC, where the component types in the coproduct are the leaf subtypes of the sealed class.
Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
def asDecoder: Decoder[A]
Gets this as a Decoder.
Gets this as a Decoder.

Definition Classes
Decoder
def asEncoder: Encoder[A]
Gets this as an Encoder.
Gets this as an Encoder.

Definition Classes
Encoder
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
final def compact: Codec[A]
Converts this codec to a new codec that compacts the encoded bit vector before returning it.
Converts this codec to a new codec that compacts the encoded bit vector before returning it.

Definition Classes
Codec → GenCodec → Encoder
final def complete: Codec[A]
Converts this codec to a new codec that fails decoding if there are remaining bits.
Converts this codec to a new codec that fails decoding if there are remaining bits.

Definition Classes
Codec → GenCodec → Decoder
final def consume[B](f: (A) ⇒ Codec[B])(g: (B) ⇒ A): Codec[B]
Similar to flatZip except the A type is not visible in the resulting type -- the binary effects of the Codec[A] still occur though.
Similar to flatZip except the A type is not visible in the resulting type -- the binary effects of the Codec[A] still occur though.
Example usage:
```
case class Flags(x: Boolean, y: Boolean, z: Boolean)
(bool :: bool :: bool :: ignore(5)).consume { flgs =>
  conditional(flgs.x, uint8) :: conditional(flgs.y, uint8) :: conditional(flgs.z, uint8)
} {
  case x :: y :: z :: HNil => Flags(x.isDefined, y.isDefined, z.isDefined) }
}
```
Note that when B is an HList, this method is equivalent to using flatPrepend and derive. That is, a.consume(f)(g) === a.flatPrepend(f).derive[A].from(g).
def contramap[C](f: (C) ⇒ A): GenCodec[C, A]
Converts this GenCodec to a GenCodec[C, B] using the supplied C => A.
Converts this GenCodec to a GenCodec[C, B] using the supplied C => A.

Definition Classes
GenCodec → Encoder
def decodeOnly[AA >: A]: Codec[AA]
Converts this to a codec that fails encoding with an error.
Converts this to a codec that fails encoding with an error.

Definition Classes
Codec → Decoder
final def decodeValue(bits: BitVector): Attempt[A]
Attempts to decode a value of type A from the specified bit vector and discards the remaining bits.
Attempts to decode a value of type A from the specified bit vector and discards the remaining bits.
bits
bits to decode
returns
error if value could not be decoded or the decoded value

Definition Classes
Decoder
def derive[A]: DeriveHListElementAux[A, A]
Supports building a Codec[M] for some HList M where M is the HList that results in removing the first A from L.
Supports building a Codec[M] for some HList M where M is the HList that results in removing the first A from L.
Example usage:
```
case class Flags(x: Boolean, y: Boolean, z: Boolean)
val c = (bool :: bool :: bool :: ignore(5)).flatPrepend { flgs =>
  conditional(flgs.x, uint8) :: conditional(flgs.y, uint8) :: conditional(flgs.z, uint8)
}
c.derive[Flags].from { case x :: y :: z :: HNil => Flags(x.isDefined, y.isDefined, z.isDefined) }
```
This codec, the Codec[L], is used for encoding/decoding. When decoding, the first value of type A is removed from the HList.
When encoding, the returned codec computes an A value using the supplied function and inserts the computed A in to the HList M, yielding an HList L. That HList L is then encoded using the original codec.
This method is called derive because the value of type A is derived from the other fields in the HList L.
A
type to remove from L and derive from the resulting list

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
final def downcast[B <: A](implicit tb: Typeable[B]): Codec[B]
Safely lifts this codec to a codec of a subtype.
Safely lifts this codec to a codec of a subtype.
When a supertype of B that is not a supertype of A is decoded, an decoding error is returned.
final def dropLeft[B](codecB: Codec[B])(implicit ev: =:=[Unit, A]): Codec[B]
Assuming A is Unit, creates a Codec[B] that: encodes the unit followed by a B; decodes a unit followed by a B and discards the decoded unit.
final def dropRight[B](codecB: Codec[B])(implicit ev: =:=[Unit, B]): Codec[A]
Assuming B is Unit, creates a Codec[A] that: encodes the A followed by a unit; decodes an A followed by a unit and discards the decoded unit.
def dropUnits[M <: HList](implicit du: Aux[A, M]): Codec[M]
Creates a new codec with all unit values filtered out.
Creates a new codec with all unit values filtered out.

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def econtramap[C](f: (C) ⇒ Attempt[A]): GenCodec[C, A]
Converts this GenCodec to a GenCodec[C, B] using the supplied C => Attempt[A].
Converts this GenCodec to a GenCodec[C, B] using the supplied C => Attempt[A].

Definition Classes
GenCodec → Encoder
def emap[C](f: (A) ⇒ Attempt[C]): GenCodec[A, C]
Converts this GenCodec to a GenCodec[A, C] using the supplied B => Attempt[C].
Converts this GenCodec to a GenCodec[A, C] using the supplied B => Attempt[C].

Definition Classes
GenCodec → Decoder
def encodeOnly: Codec[A]
Converts this to a codec that fails decoding with an error.
Converts this to a codec that fails decoding with an error.

Definition Classes
Encoder
def ensuring(cond: (Codec[A]) ⇒ Boolean, msg: ⇒ Any): Codec[A]

Implicit
This member is added by an implicit conversion from Codec[A] to Ensuring[Codec[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (Codec[A]) ⇒ Boolean): Codec[A]

Implicit
This member is added by an implicit conversion from Codec[A] to Ensuring[Codec[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: ⇒ Any): Codec[A]

Implicit
This member is added by an implicit conversion from Codec[A] to Ensuring[Codec[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): Codec[A]

Implicit
This member is added by an implicit conversion from Codec[A] to Ensuring[Codec[A]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def exmap[B](f: (A) ⇒ Attempt[B], g: (B) ⇒ Attempt[A]): Codec[B]
Transforms using two functions, A => Attempt[B] and B => Attempt[A].
def exmapc[B](f: (A) ⇒ Attempt[B])(g: (B) ⇒ Attempt[A]): Codec[B]
Curried version of exmap.
Curried version of exmap.

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
def flatAppend[A, LA <: HList, Len <: Nat](f: (A) ⇒ Codec[A])(implicit prepend: shapeless.ops.hlist.Prepend.Aux[A, ::[A, HNil], LA], length: Aux[A, Len], split: Aux[LA, Len, A, ::[A, HNil]]): Codec[LA]
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList L followed by the value A, where the latter is encoded/decoded with the codec returned from applying L to f.
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList L followed by the value A, where the latter is encoded/decoded with the codec returned from applying L to f.

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def flatConcat[M <: HList, LM <: HList, LLen <: Nat](f: (A) ⇒ Codec[M])(implicit prepend: shapeless.ops.hlist.Prepend.Aux[A, M, LM], lengthK: Aux[A, LLen], split: Aux[LM, LLen, A, M]): Codec[LM]
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList L followed by the HList M, where the latter is encoded/decoded with the codec returned from applying L to f.
When called on a Codec[L] for some L <: HList, returns a new codec that encodes/decodes the HList L followed by the HList M, where the latter is encoded/decoded with the codec returned from applying L to f.

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def flatMap[B](f: (A) ⇒ Decoder[B]): Decoder[B]
Converts this decoder to a Decoder[B] using the supplied A => Decoder[B].
Converts this decoder to a Decoder[B] using the supplied A => Decoder[B].

Definition Classes
Decoder
def flatPrepend[L <: HList](f: (A) ⇒ Codec[L]): Codec[::[A, L]]
Creates a new codec that encodes/decodes an HList type of A :: L given a function A => Codec[L].
Creates a new codec that encodes/decodes an HList type of A :: L given a function A => Codec[L]. This allows later parts of an HList codec to be dependent on earlier values.

Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithHListSupport[A] performed by method ValueCodecEnrichedWithHListSupport in scodec.
Definition Classes
ValueCodecEnrichedWithHListSupport
final def flatZip[B](f: (A) ⇒ Codec[B]): Codec[(A, B)]
Returns a new codec that encodes/decodes a value of type (A, B) where the codec of B is dependent on A.
def flatZipHList[B](f: (A) ⇒ Codec[B]): Codec[::[A, ::[B, HNil]]]
Creates a new codec that encodes/decodes an HList type of A :: B :: HNil given a function A => Codec[B].
Creates a new codec that encodes/decodes an HList type of A :: B :: HNil given a function A => Codec[B]. If B is an HList type, consider using flatPrepend instead, which avoids nested HLists. This is the direct HList equivalent of flatZip.

Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithHListSupport[A] performed by method ValueCodecEnrichedWithHListSupport in scodec.
Definition Classes
ValueCodecEnrichedWithHListSupport
final def flattenLeftPairs(implicit f: FlattenLeftPairs[A]): Codec[Out]
Converts this codec to an HList based codec by flattening all left nested pairs.
Converts this codec to an HList based codec by flattening all left nested pairs. For example, flattenLeftPairs on a Codec[(((A, B), C), D)] results in a Codec[A :: B :: C :: D :: HNil]. This is particularly useful when combined with ~, ~>, and <~.
def formatted(fmtstr: String): String

Implicit
This member is added by an implicit conversion from Codec[A] to StringFormat[Codec[A]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()
final def fuse[AA <: A, BB >: A](implicit ev: =:=[BB, AA]): Codec[BB]
Converts this generalized codec in to a non-generalized codec assuming A and B are the same type.
Converts this generalized codec in to a non-generalized codec assuming A and B are the same type.

Definition Classes
GenCodec
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
AnyRef → Any
final def hlist: Codec[::[A, HNil]]
Lifts this codec in to a codec of a singleton hlist.
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
def map[C](f: (A) ⇒ C): GenCodec[A, C]
Converts this GenCodec to a GenCodec[A, C] using the supplied B => C.
Converts this GenCodec to a GenCodec[A, C] using the supplied B => C.

Definition Classes
GenCodec → Decoder
final def narrow[B](f: (A) ⇒ Attempt[B], g: (B) ⇒ A): Codec[B]
Transforms using two functions, A => Attempt[B] and B => A.
Transforms using two functions, A => Attempt[B] and B => A.
The supplied functions form an injection from B to A. Hence, this method converts from a larger to a smaller type. Hence, the name narrow.
def narrowc[B](f: (A) ⇒ Attempt[B])(g: (B) ⇒ A): Codec[B]
Curried version of narrow.
Curried version of narrow.

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
final def pairedWith[B](codecB: Codec[B]): Codec[(A, B)]
Creates a Codec[(A, B)] that first encodes/decodes an A followed by a B.
def pcontramap[C](f: (C) ⇒ Option[A]): GenCodec[C, A]
Converts this GenCodec to a GenCodec[C, B] using the supplied partial function from C to A.
Converts this GenCodec to a GenCodec[C, B] using the supplied partial function from C to A. The encoding will fail for any C that f maps to None.

Definition Classes
GenCodec → Encoder
def polyxmap[B](p: Poly, q: Poly)(implicit aToB: Aux[p.type, ::[A, HNil], B], bToA: Aux[q.type, ::[B, HNil], A]): Codec[B]
Polymorphic function version of xmap.
Polymorphic function version of xmap.
When called on a Codec[A] where A is not a subytpe of HList, returns a new codec that's the result of xmapping with p and q, using p to convert from A to B and using q to convert from B to A.
p
polymorphic function that converts from A to B
q
polymorphic function that converts from B to A

Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithGenericSupport[A] performed by method ValueCodecEnrichedWithGenericSupport in scodec.
Definition Classes
ValueCodecEnrichedWithGenericSupport
def polyxmap[M <: HList](p: Poly, q: Poly)(implicit lToM: Aux[p.type, A, M], mToL: Aux[q.type, M, A]): Codec[M]
Polymorphic function version of xmap.
Polymorphic function version of xmap.
When called on a Codec[L] for some L <: HList, returns a new codec that's the result of xmapping with p and q, using p to convert from L to M and using q to convert from M to L.
p
polymorphic function that converts from L to M
q
polymorphic function that converts from M to L

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def polyxmap1[B](p: Poly)(implicit aToB: Aux[p.type, ::[A, HNil], B], bToA: Aux[p.type, ::[B, HNil], A]): Codec[B]
Polymorphic function version of xmap that uses a single polymorphic function in both directions.
Polymorphic function version of xmap that uses a single polymorphic function in both directions.
When called on a Codec[A] where A is not a subytpe of HList, returns a new codec that's the result of xmapping with p for both forward and reverse directions.
p
polymorphic function that converts from A to B and from B to A

Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithGenericSupport[A] performed by method ValueCodecEnrichedWithGenericSupport in scodec.
Definition Classes
ValueCodecEnrichedWithGenericSupport
def polyxmap1[M <: HList](p: Poly)(implicit m: Aux[p.type, A, M], m2: Aux[p.type, M, A]): Codec[M]
Polymorphic function version of xmap that uses a single polymorphic function in both directions.
Polymorphic function version of xmap that uses a single polymorphic function in both directions.
When called on a Codec[L] for some L <: HList, returns a new codec that's the result of xmapping with p for both forward and reverse directions.
p
polymorphic function that converts from L to M and from M to L

Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Definition Classes
HListCodecEnrichedWithHListSupport
def selectDecoder[A](implicit sel: Selector[A, A]): Decoder[Option[A]]
When called on a Decoder[C] where C is a coproduct containing type A, converts to a Decoder[Option[A]].
When called on a Decoder[C] where C is a coproduct containing type A, converts to a Decoder[Option[A]].

Implicit
This member is added by an implicit conversion from Codec[A] to EnrichedCoproductDecoder[A] performed by method EnrichedCoproductDecoder in scodec. This conversion will take place only if A is a subclass of Coproduct (A <: Coproduct).
Definition Classes
EnrichedCoproductDecoder
def selectEncoder[A](implicit inj: Inject[Coproduct, A]): Encoder[A]
When called on a Encoder[C] where C is a coproduct containing type A, converts to an Encoder[A].
When called on a Encoder[C] where C is a coproduct containing type A, converts to an Encoder[A].

Implicit
This member is added by an implicit conversion from Codec[A] to EnrichedCoproductEncoder[Coproduct] performed by method EnrichedCoproductEncoder in scodec. This conversion will take place only if A is a superclass of Coproduct (A >: Coproduct).
Definition Classes
EnrichedCoproductEncoder
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toField[K]: Codec[FieldType[K, A]]
Lifts this codec to a codec of a shapeless field -- allowing it to be used in records and unions.
def toFieldWithContext[K <: Symbol](k: K): Codec[FieldType[K, A]]
Lifts this codec to a codec of a shapeless field -- allowing it to be used in records and unions.
Lifts this codec to a codec of a shapeless field -- allowing it to be used in records and unions. The specified key is pushed in to the context of any errors that are returned from the resulting codec.
def toString(): String

Definition Classes
AnyRef → Any
final def unit(zero: A): Codec[Unit]
Converts this to a Codec[Unit] that encodes using the specified zero value and decodes a unit value when this codec decodes an A successfully.
final def upcast[B >: A](implicit ta: Typeable[A]): Codec[B]
Safely lifts this codec to a codec of a supertype.
Safely lifts this codec to a codec of a supertype.
When a subtype of B that is not a subtype of A is passed to encode, an encoding error is returned.
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def widen[B](f: (A) ⇒ B, g: (B) ⇒ Attempt[A]): Codec[B]
Transforms using two functions, A => B and B => Attempt[A].
Transforms using two functions, A => B and B => Attempt[A].
The supplied functions form an injection from A to B. Hence, this method converts from a smaller to a larger type. Hence, the name widen.
def widenOpt[B](f: (A) ⇒ B, g: (B) ⇒ Option[A]): Codec[B]
Transforms using two functions, A => B and B => Option[A].
Transforms using two functions, A => B and B => Option[A].
Particularly useful when combined with case class apply/unapply. E.g., widenOpt(fa, Foo.apply, Foo.unapply).

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
def widenOptc[B](f: (A) ⇒ B)(g: (B) ⇒ Option[A]): Codec[B]
Curried version of widenOpt.
Curried version of widenOpt.

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
def widenc[B](f: (A) ⇒ B)(g: (B) ⇒ Attempt[A]): Codec[B]
Curried version of widen.
Curried version of widen.

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
final def withContext(context: String): Codec[A]
Creates a new codec that is functionally equivalent to this codec but pushes the specified context string in to any errors returned from encode or decode.
final def withToString(str: ⇒ String): Codec[A]
Creates a new codec that is functionally equivalent to this codec but returns the specified string from toString.
final def xmap[B](f: (A) ⇒ B, g: (B) ⇒ A): Codec[B]
Transforms using the isomorphism described by two functions, A => B and B => A.
def xmapc[B](f: (A) ⇒ B)(g: (B) ⇒ A): Codec[B]
Curried version of xmap.
Curried version of xmap.

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
final def ~[B](codecB: Codec[B]): Codec[(A, B)]
Creates a Codec[(A, B)] that first encodes/decodes an A followed by a B.
Creates a Codec[(A, B)] that first encodes/decodes an A followed by a B.
Operator alias for pairedWith.
final def ~>[B](codecB: Codec[B])(implicit ev: =:=[Unit, A]): Codec[B]
Assuming A is Unit, creates a Codec[B] that: encodes the unit followed by a B; decodes a unit followed by a B and discards the decoded unit.
Assuming A is Unit, creates a Codec[B] that: encodes the unit followed by a B; decodes a unit followed by a B and discards the decoded unit.
Operator alias of dropLeft.
def ~~[B](B: Codec[B]): TupleCodec[A, B]

Implicit
This member is added by an implicit conversion from Codec[A] to Tuple2CodecSupport[A] performed by method Tuple2CodecSupport in scodec.
Definition Classes
Tuple2CodecSupport
def →[B](y: B): (Codec[A], B)

Implicit
This member is added by an implicit conversion from Codec[A] to ArrowAssoc[Codec[A]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc

Shadowed Implicit Value Members

def exmap[B](f: (A) ⇒ Attempt[B], g: (B) ⇒ Attempt[A]): Codec[B]
Transforms using two functions, A => Attempt[B] and B => Attempt[A].
Transforms using two functions, A => Attempt[B] and B => Attempt[A].
Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(codec: TransformSyntax[Codec, A]).exmap(f, g)
Definition Classes
TransformSyntax
def narrow[B](f: (A) ⇒ Attempt[B], g: (B) ⇒ A): Codec[B]
Transforms using two functions, A => Attempt[B] and B => A.
Transforms using two functions, A => Attempt[B] and B => A.
The supplied functions form an injection from B to A. Hence, this method converts from a larger to a smaller type. Hence, the name narrow.
Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(codec: TransformSyntax[Codec, A]).narrow(f, g)
Definition Classes
TransformSyntax
val self: Codec[A]
Implicit
This member is added by an implicit conversion from Codec[A] to Tuple2CodecSupport[A] performed by method Tuple2CodecSupport in scodec.
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: Tuple2CodecSupport[A]).self
Definition Classes
Tuple2CodecSupport
val self: Decoder[A]
Implicit
This member is added by an implicit conversion from Codec[A] to EnrichedCoproductDecoder[A] performed by method EnrichedCoproductDecoder in scodec. This conversion will take place only if A is a subclass of Coproduct (A <: Coproduct).
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: EnrichedCoproductDecoder[A]).self
Definition Classes
EnrichedCoproductDecoder
val self: Encoder[Coproduct]
Implicit
This member is added by an implicit conversion from Codec[A] to EnrichedCoproductEncoder[Coproduct] performed by method EnrichedCoproductEncoder in scodec. This conversion will take place only if A is a superclass of Coproduct (A >: Coproduct).
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: EnrichedCoproductEncoder[Coproduct]).self
Definition Classes
EnrichedCoproductEncoder
val self: Codec[A]
Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithGenericSupport[A] performed by method ValueCodecEnrichedWithGenericSupport in scodec.
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: ValueCodecEnrichedWithGenericSupport[A]).self
Definition Classes
ValueCodecEnrichedWithGenericSupport
val self: Codec[A]
Implicit
This member is added by an implicit conversion from Codec[A] to ValueCodecEnrichedWithHListSupport[A] performed by method ValueCodecEnrichedWithHListSupport in scodec.
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: ValueCodecEnrichedWithHListSupport[A]).self
Definition Classes
ValueCodecEnrichedWithHListSupport
val self: Codec[A]
Implicit
This member is added by an implicit conversion from Codec[A] to HListCodecEnrichedWithHListSupport[A] performed by method HListCodecEnrichedWithHListSupport in scodec. This conversion will take place only if A is a subclass of HList (A <: HList).
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: HListCodecEnrichedWithHListSupport[A]).self
Definition Classes
HListCodecEnrichedWithHListSupport
val self: Codec[A]
Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Shadowing
This implicitly inherited member is ambiguous. One or more implicitly inherited members have similar signatures, so calling this member may produce an ambiguous implicit conversion compiler error.
To access this member you can use a type ascription:
(codec: TransformSyntax[Codec, A]).self
Definition Classes
TransformSyntax
def widen[B](f: (A) ⇒ B, g: (B) ⇒ Attempt[A]): Codec[B]
Transforms using two functions, A => B and B => Attempt[A].
Transforms using two functions, A => B and B => Attempt[A].
The supplied functions form an injection from A to B. Hence, this method converts from a smaller to a larger type. Hence, the name widen.
Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(codec: TransformSyntax[Codec, A]).widen(f, g)
Definition Classes
TransformSyntax
def xmap[B](f: (A) ⇒ B, g: (B) ⇒ A): Codec[B]
Transforms using the isomorphism described by two functions, A => B and B => A.
Transforms using the isomorphism described by two functions, A => B and B => A.
Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Shadowing
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
(codec: TransformSyntax[Codec, A]).xmap(f, g)
Definition Classes
TransformSyntax

Deprecated Value Members

def pxmap[B](f: (A) ⇒ B, g: (B) ⇒ Option[A]): Codec[B]
Transforms using two functions, A => B and B => Option[A].
Transforms using two functions, A => B and B => Option[A].
Particularly useful when combined with case class apply/unapply. E.g., pxmap(fa, Foo.apply, Foo.unapply).

Implicit
This member is added by an implicit conversion from Codec[A] to TransformSyntax[Codec, A] performed by method TransformSyntax in scodec.
Definition Classes
TransformSyntax
Annotations
@deprecated
Deprecated
(Since version 1.7.0) Use widenOpt instead

Packages

Bits and Bytes Codecs

Numeric Codecs

Miscellaneous Value Codecs

Combinators

Cryptography Codecs

Codec 

Companion object Codec

trait Codec[A] extends GenCodec[A, A]

Tuple Codecs

flatZip

HList Codecs

flatPrepend

Coproduct Codecs

Derived Codecs

Implicit Codecs

Abstract Value Members

Concrete Value Members

Shadowed Implicit Value Members

Deprecated Value Members

Inherited from GenCodec[A, A]

Inherited from Decoder[A]

Inherited from Encoder[A]

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion Tuple2CodecSupport from Codec[A] to Tuple2CodecSupport[A]

Inherited by implicit conversion EnrichedCoproductDecoder from Codec[A] to EnrichedCoproductDecoder[A]

Inherited by implicit conversion EnrichedCoproductEncoder from Codec[A] to EnrichedCoproductEncoder[Coproduct]

Inherited by implicit conversion ValueCodecEnrichedWithGenericSupport from Codec[A] to ValueCodecEnrichedWithGenericSupport[A]

Inherited by implicit conversion ValueCodecEnrichedWithHListSupport from Codec[A] to ValueCodecEnrichedWithHListSupport[A]

Inherited by implicit conversion HListCodecEnrichedWithHListSupport from Codec[A] to HListCodecEnrichedWithHListSupport[A]

Inherited by implicit conversion TransformSyntax from Codec[A] to TransformSyntax[Codec, A]

Inherited by implicit conversion any2stringadd from Codec[A] to any2stringadd[Codec[A]]

Inherited by implicit conversion StringFormat from Codec[A] to StringFormat[Codec[A]]

Inherited by implicit conversion Ensuring from Codec[A] to Ensuring[Codec[A]]

Inherited by implicit conversion ArrowAssoc from Codec[A] to ArrowAssoc[Codec[A]]

Primary Members

Basic Combinators

Tuple Support

HList Support

Coproduct Support

Generic Support

Ungrouped

Codec