# Expression
An expression is a combination of one or more constants, variables, operators and function calls.
Ride interprets the expression and calculates its result.
# Expression result
An expression result is a value, which is obtained by the fold of the syntactic tree of the expression.
# Expression type
An expression type is a data type of the expression result.
# Examples
The expression that consists of a single constant.
7
The expression that consists of a single variable.
x
The expression that consists of the constant 7, operators + and *, variable x and the size function call.
7 + x * size("apple")