planned-types.md

Additional Types

128-bit Integer Types

Additional integer types for signed and unsigned 128-bit integers.

integer_type
    : ...
    | "int128"
    | "uint128"
    ;

128-bit Floating Point Type

Additional floating point type for IEEE 754 binary128 floating point math.

floating_point_type
    : ...
    | "float128"
    ;

Fixed Point Types

Fixed point types are an additional class of simple numeric types.

numeric_type
    : ...
    | fixed_point_type
    ;

fixed_point_type
    : "fixed" [0-9]+ "." [0-9]+
    | "ufixed" [0-9]+ "." [0-9]+
    ;

Let f be the number of fractional bits, m be the number of magnitude or integer bits and b be the total number of bits. For b=m+f where b=8 or b=16 or b=32 or b=64 and m > 0, f > 0, the signed fixed point type is fixedm.f and the unsigned type is ufixedm.f.

Note: 128 bit fixed types are not supported because of issues with handling multiply.

Decimal Types

Decimal types are an additional class of simple numeric types.

numeric_type
    : ...
    | decimal_type
    ;

decimal_type
    : "decimal32"
    | "decimal"
    | "decimal128"
    ;

They provide IEEE 754 32-bit, 64-bit and 128-bit decimal numbers respectively (binary representation preferred).

DEC64 Type

The "system.math" package will define the dec64 type following the standard defined on dec64.org.

Rational Type

The "system.math" package will define the rational type. It is an arbitrary precision rational number. This may be represented either as integer/uinteger or the one described in A New Representation of the Rational Numbers for Fast Easy Arithmetic by Eric C. R. Hehner and R. N. S. Horspool.

Real Types

Arbitrary precision real number types could be very useful. However, their behavior for representing an irrational numbers would need to be clarified. For an example of how this type might work, see the Java System.Numerics.BigDecimal type. It may also be useful to have types with a fixed number of fractional digits. These could be simple types or defined in the "system.math" namespace.

numeric_type
    : ...
    | real_type
    ;

real_type
    : "real"
    | "real." [0-9]+
    ;

If these types are defined in the standard library, then "real\.\d+" could instead be "real[f]".

Money Type

Although C# recommends using the "decimal" type for money because it exhibits decimal rounding, its underflow and overflow behavior is not ideal for money. Perhaps there should be a decimal type or types more suitable for money.