ursa-major

Define structs in Earl Grey with typing and validation.

Basic usage

Require the macro like this (require-macro, not require):

require-macros:
   ursa-major -> struct

A struct is defined like this. Fields marked maybe can either be of the specified type, or they can be null:

struct Person:
   ;; use the uuid command in the console to generate a unique id for your struct
   ;; Try to add /StructName to the end of the uuid for readability, like this:
   type-id: "46cb4b46-35b8-11e5-9645-e3f320d7342e/Person"
   String? name
   Number? age
   maybe Person? mother
   maybe Person? father

Structs are instantiated with a dictionary of the required properties:

p1 = Person(name = "Florence", age = 43)
p2 = Person(name = "Rashid", age = 57)
p3 = Person(name = "Emily", age = 23, mother = p1, father = p2)

Serialize/deserialize with kaiser. type-id must be defined for the struct in order for this to work.

require: kaiser

serialized = kaiser.serialize(p3)
deserialized = kaiser.deserialize(serialized)

Validation

A validate method can be defined by a struct in order to ensure it is in a consistent state. For example:

struct OrderedTriple:
   Number? a
   Number? b
   Number? c
   validate() =
      if @a > @b or @b > @c:
         throw E.not-ordered("The order a < b < c failed to be preserved.")

OrderedTriple(a = 1, b = 2, c = 3)    ;; OK!
OrderedTriple(a = 1, b = -2, c = 3)   ;; ERROR!

validate is called whenever properties are set:

o = OrderedTriple(a = 1, b = 2, c = 3)
o.b = -2  ;; ERROR!

The update method can set many fields at once:

o = OrderedTriple(a = 1, b = 2, c = 3)
o.update(a = 100, b = 200, c = 300)  ;; OK!