Types #

SCIF is statically typed, meaning that each variable and method type needs to be specified at compile time. However, SCIF provides inference mechanisms to infer labels for programmer's convenience.

Primitive types #

• bool: Boolean values true or false.
• uint: Unsigned integers whose possible values are between 0 and 2²⁵⁶ - 1.
• byte: Byte values. Possible values are between 0 and 2⁸ - 1.
• address: Address of an Ethereum account, represented as 20 bytes.

Arrays #

T[n] is the type of an array of element type T and fixed length n. For example, uint[10] is the type of a uint array with 10 elements. Indices are zero-based.

Maps #

map(keyType, valueType) represents a map from type keyType to type valueType. For example, map(address, uint) maps from address to uint.

keyType can be any primitive type, while valueType can be any type, including maps and user-defined classes.

The values in a map m with key k is accessed through the expression m[k].

Classes and Contracts #

• Contract Types: Every defined contract can be explicitly converted from and to the address type.

Labels #

Each variable type in SCIF is associated with a label representing its level of integrity. T{l} describes a type T associated with the label l.

For example:

uint{trusted} x;
uint{untrusted} y;
x = y; // compile error
y = x; // pass

x is labeled as trusted while y is labeled as untrusted. So when x is reassigned to y, the compiler will not compile because, assuming trusted and untrusted are defined in a reasonable way, it is an integrity failure for an untrusted value to be assigned to a trusted variable.

If a label is not specified when declaring a variable, the compiler will either infer a label from the context or assign a default label to it.