typelet

Typelet - an extensible type framework.

Install

npm install typelet

Usage

var Type = require('typelet');

Type checking:

Type.Integer.isa(1); // ==> true
Type.Integer.isa(1.5); // ==> false
Type.Float.isa(1.5); // ==> true

// compound types.
var intArrayType = Type.ArrayType(Type.Integer)
intArrayType.isa([1, 2, 3, 4, 5]); // ==> true
var objFooType = Type.ObjectType({ foo: Type.Integer, bar: Type.String });
objFooType.isa({foo: 1, bar: 'a string'}); // ==> true
objFooType.isa({foo: 1, baz: 2}); // ==> false

Type checking via assert:

Type.Integer.assert(1); // OK
Type.Integer.assert(1.5); // throws
intArrayType.assert([1, 'not an int']); // throws
objFooType.assert({foo: 1, bar: 'a string'}); // OK
objFooType.assert({foo: 1, bar: 'a string', baz: 2}); // OK - ObjectType is okay with additional attributes.
objFooType.assert({foo: 1, bar: 2}); // throws

Type conversion:

var val = Type.Integer.convert('1'); // string -> int
var val = Type.Integer.convert('not an int'); // throws

JSON Schema support (limited at this time):

Type.JsonSchema.build({ type: 'integer' }) // ==> Type.Integer
Type.JsonSchema.build({ type: 'number' }) // ==> Type.Float
Type.JsonSchema.build({ type: 'string' }) // ==> Type.String
Type.JsonSchema.build({ type: 'boolean' }) // ==> Type.Boolean
Type.JsonSchema.build({ type: 'null' }) // ==> Type.Null
Type.JsonSchema.build({ type: 'array', items: { type: 'integer' }) // ==> Type.ArrayType(Type.Integer)
Type.JsonSchema.build({ type: 'object',
  properties: {
    foo: { type: 'integer' },
bar: { type: 'number' }
  }
}) // Type.ObjectType({ foo: Type.Integer, bar: Type.Float })
Type.JsonSchema.build({ type: [ 'integer', 'null' ] }) // Type.OneOfType(Type.Integer, Type.Null)
Type.JsonSchema.build({ oneOf: [
  { type: 'integer' },
  { type: 'null' }
]}) // same as above, Type.OneOfType(Type.Integer, Type.Null)

Note that typelet contains types that do not exist in Json Schema as well.

Built-In Types

Built-in types currently follows JavaScript built-in types.

• Scalar Types
  • unit (Type.Unit) - maps to undefined in JavaScript.
  • null (Type.Null) - maps to null in JavaScript.
  • boolean (Type.Boolean) maps to true and false in JavaScript.
  • integer (Type.Integer)
  • float (Type.Float) - NaN is not considered a number in this type system.
  • string (Type.String)
  • date (Type.Date)
• Compound Types
  • array (Type.ArrayType(<type>))
  • object (Type.ObjectType({ key1: <type1>, key2: <type2>, ...}))
  • disjoint union (Type.OneOf(<type1>, <type2>, ...))
  • procedure (Type.ProcedureType([<argType1>, ...], <returnType>))