5.5.7.3 Symbols as Denoting Variables

When an unquoted symbol in a Scheme program is evaluated, it is interpreted as a variable reference, and the result of the evaluation is the appropriate variable's value.

For example, when the expression (string-length "abcd") is read and evaluated, the sequence of characters string-length is read as the symbol whose name is "string-length". This symbol is associated with a variable whose value is the procedure that implements string length calculation. Therefore evaluation of the string-length symbol results in that procedure.

The details of the connection between an unquoted symbol and the variable to which it refers are explained elsewhere. See Binding Constructs, for how associations between symbols and variables are created, and Modules, for how those associations are affected by Guile's module system.