Skip to content

Baker Types and Values

Because of the distributed nature of Baker and how the runtime works, we need to have serializable types and values to transfer recipes and data between nodes and to match over such data, that is why we implemented a type system on top of Scala. They help not just to model your domain but also for Baker to identify when to execute interactions.

If you are using all of our reflection APIs then you will not use them directly, but it is good to know of their existence.


val data: (Type, Value) = (Int32, PrimitiveValue(42))

Type dataType = Int32$.MODULE$;
Value dataValue = PrimitiveValue.apply(42);

Types are specifically used to describe Ingredients, specifically Ingredients are just a relation between a name and a type.

In a similar way that a programming language variable is just a relation between a name and a type at compile time, the baker Ingredient is a relation between a name and a Baker Type at "recipe time"; the same happens with values, in a programming language values must respect types otherwise runtime exceptions are thrown, similarly in Baker, at runtime the name of an ingredient will hold a value that respects the ingredient's type.

Here is a complete list of Types and Values of Baker.


Type Java parallel Description
Bool boolean single bit, true or false, 1 or 0
Char char Unsigned 16 bit integer
Byte byte Signed 8 bit integer
Int16 short Signed 16 bit integer
Int32 int Signed 32 bit integer
Int64 long Signed 64 bit integer
IntBig BigInteger Integer of arbitrary size
Float32 float Signed 32 bit floating point
Float64 double Signed 64 bit floating point
FloatBig BigDecimal Floating point of arbitrary size
Date long A UTC date in the ISO-8601 calendar system with millisecond precision
ByteArray Array<Byte> Byte array, often used for binary data
CharArray String Character array, or commmonly called String

Structured types

Type Java parallel Description
ListType<T> java.util.List<T> A list of values, all of the same type
OptionType<T> java.util.Optional<T> Matches against T or null
EnumType enum class A set of predifined options (strings)
RecordType POJO class A record with a specific set of fields
MapType<T> java.util.Map<String, T> A record with arbitrary fields, all of the same type


Values are pure data without any direct associated type. These very closely match the JSON data format.

Value Description
NullValue Analogues to null, Optional.empty, None, etc ...
PrimitiveValue Wrapper for for:
- A Java primitive (or boxed variant)
- java.lang.String
- java.math.BigInteger
- java.math.BigDecimal
- scala.math.BigInt
- Array<Byte>
ListValue A list of values
RecordValue A set of String -> Value pairs

Interoptability with java types

Because it is impractical to directly work with the baker types in java/scala code there is conversion system.

Default supported types


  • primitives and their boxed variants
  • Enum types
  • java.util.List
  • java.util.Set
  • java.util.Map
  • java.math.BigInt
  • java.math.BigDecimal
  • java.util.Optional
  • POJO classes


  • primitives and their boxed variants
  • case classes
  • scala.collection.immutable.List
  • scala.collection.immutable.Set
  • scala.collection.immutable.Map
  • BigInt
  • BigDecimal
  • scala.Option

Registering a custom type adapter

All default type adapters are registered in the reference.conf of the baker-types module.

You can add your custom type adapter by registering it in a reference.conf.

baker.types {

   "com.example.MyCustomType" = "com.example.MyCustomTypeAdpater"

For an example how to implement an adapter see here