This is a glossary that contains terms related to programming in the context of Lua. Its use is recommended to find the meaning of words that are not understood.
An abstract data type is a model to represent a class of data structures that have similar behavior. Abstract data types are defined by the operations that can be performed on them and by mathematical constraints of these operations rather than by the implementation and the way the data is stored in the memory of the computer.
An associative array is an abstract data type composed of a collection of pairs of keys and values, such that each possible key appears at most once in the collection.
A condition is a predicate that is used in a conditional statement or as an operand to the conditional operator. Conditions, in Lua, are considered as true when their expression evaluates to a value other than nil or false, and are considered as false otherwise.
Venn diagram of The exclusive disjunction operation is a binary operation that produces the value true when one of its operands is true but the other is not. The exclusive disjunction of a and b is expressed mathematically as . There is no operator corresponding to exclusive disjunction in Lua, but can be represented as (a or b) and not (a and b).
A function is a sequence of statements (instructions) that perform a specific task. Functions can be used in a program wherever that particular task needs to be performed. Functions are usually defined in the program that will use them, but are sometimes defined in libraries that can be used by other programs.
A hash table is an implementation as a data structure of the associative array. A hash table uses a hash function to compute an index into an array of buckets or slots, from which the value corresponding to the index can be found.
An integer is a number that can be written without a fractional or decimal component. Integers are implemented in Lua in the same way as other numbers.
The logical complement of a boolean value is the boolean value that is not that value. This means the logical complement of true is false and vice versa.
Venn diagram of The logical conjunction operation is a binary operation that produces the value true when both of its operands are true and false in all other cases. It is implemented as the and operator in Lua and it returns its first operand if it is false or nil and the second operand otherwise. The logical conjunction of a and b is expressed mathematically as .
Venn diagram of The logical disjunction operation is a binary operation that produces the value false when both of its operands are false and true in all other cases. It is implemented as the or operator in Lua and it returns the first operand if it is neither false nor nil and the second otherwise. The logical disjunction of a and b is expressed mathematically as .
The type nil is the type of the value nil, whose main property is to be different from any other value; it usually represents the absence of a useful value.
The number type represents real (double-precision floating-point) numbers. It is possible to build Lua interpreters that use other internal representations for numbers, such as single-precision float or long integers.
A string literal is the representation of a string value within the source code of a computer program. With respect to syntax, a string literal is an expression that evaluates to a string.
A token is an atomic piece of data, such as a word in a human language or such as a keyword in a programming language, for which a meaning may be inferred during parsing.
