types.md

Types

MAGES maps every .NET data type to one of its data types:

• Number (System.Double)
• Boolean (System.Boolean)
• String (System.String)
• Matrix (System.Double[,])
• Complex (System.Numerics.Complex)
• Complex Matrix (System.Numerics.Complex[,])
• Object (System.Collections.Generic.IDictionary<System.String, System.Object>)
• Function (Mages.Core.Function, essentially a Delegate mapping Object[] to Object)
• Nothing (null)

These seven kinds of types spawn the whole set of capabilities offered by MAGES. For instance, even if we use a function like catch (see Functions) the result will be an IDictionary<String, Object> instance. There is no special type returned.

Type Mapping

The following table yields the essential type mapping.

MAGES	.NET
Complex	Complex
Number	Double
	Single
	Decimal
	Byte
	UInt16
	UInt32
	UInt64
	Int16
	Int32
	Int64
Boolean	Boolean
String	String
	Char
CMatrix	Complex[,]
Matrix	Double[,]
	Double[]
	List
Function	Function
	Delegate
Object	IDictionary<String, Object>
	Object
Nothing	null

The table on described the direct relations. Furthermore, there are some additional relations.

Type Casting

MAGES allows casting between its own types. For instance, any number can be casted to a boolean with the negate operator ~.

~~1.5 // true
~~0 // false

There are also other occasions where numbers are transformed to booleans. Similarly, strings transform to boolean.

~~"test" // true
~~"" // false

Therefore any non-empty string represents true. Empty strings are interpreted as false.

Objects are false if they are empty. So we show the following examples:

~~new { a: 0 } // true
~~new { } // false

Functions are always true. Nothing is always false. The big exception to all the shown identities are matrices. Here the not operator only transforms the matrix to a logical matrix (only consisting of zeros and ones, but still equivalent to a .NET double[,]). This is time to introduce to useful logical helper functions, all and any. Both of them transform any non-matrix value as booleans - as seen previously. However, for matrices they do not stop at logical matrices, but go all the way to booleans.

any([0, 0, 1]) // true
all([0, 0, 1]) // false
any([0, 0, 0]) // false
all([1, 1, 1]) // true

any returns true once any non-zero value is found in the matrix. all returns false once any zero value is found in the matrix.

The following tables yield information on casting possibilities.

From x	To y	Code
Number	Boolean	y = any(x)
	String	y = stringify(x)
	Matrix	y = x'
Complex	Boolean	y = any(x)
	String	y = stringify(x)
	Matrix	y = x'
Boolean	Number	y = +x
	String	y = stringify(x)
	Matrix	y = x'
String	Number	y = +x
	Boolean	y = any(x)
	Matrix	y = x'
CMatrix	Number	(nothing)
	Boolean	y = any(x)
	String	y = stringify(x)
Matrix	Number	(nothing)
	Boolean	y = any(x)
	String	y = stringify(x)
Object	Number	y = +x // NaN
	Boolean	y = any(x)
	String	y = stringify(x)
	Matrix	y = x' // [NaN]
Function	Number	y = +x // NaN
	Boolean	y = any(x) // true
	String	y = stringify(x)
	Matrix	y = x' // NaN
Nothing	Boolean	y = any(x) // false
	String	y = stringify(x)
	Matrix	y = x' // [NaN]

Things that have not been mentioned, e.g., casting from number to function are not directly possible, but can be done trivially. For instance, a number x can be brought into a function y by writing y = () => x. Similarly, everything can be converted to an object. Here we just need to know what we call the key. If we go with the name value then we can use y = new { value: x } to transform any value to an object.

For transforming a matrix into a number multiple ways are possible. If the cast is required internally then the first value is picked if there is just a single value. Otherwise NaN is taken due to ambiguity. Explicitly, however, there are multiply options, e.g., picking a specific element, performing a special operation such as det or trace, or using a self-defined way.

Type Checking

Furthermore, two interesting functions exist: is and as. Both take a type name (e.g., Number) and a value as arguments. However, while the former returns a boolean value indicating if the value is of the given type, the latter returns the converted value or undefined.