Symbol Tables

Symbol Tables are a language feature.

In computer science, a symbol table is a data structure used by a language translator such as a compiler or interpreter, where each identifier (a.k.a. symbol) in a program's source code is associated with information relating to its declaration or appearance in the source. In other words, the entries of a symbol table store the information related to the entry's corresponding symbol.. Read more on Wikipedia...

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Languages with Symbol Tables include C, Python, Racket

Example from C:

// Declare an external function
extern double bar(double x);

// Define a public function
double foo(int count)
{
    double  sum = 0.0;

    // Sum all the values bar(1) to bar(count)
    for (int i = 1;  i <= count;  i++)
        sum += bar((double) i);
    return sum;
}
// Symbol Table:
// Symbol name|Type|Scope
// bar|function, double|extern
// x|double|function parameter
// foo|function, double|global
// count|int|function parameter
// sum|double|block local
// i|int|for-loop statement

Example from Python:

# https://eli.thegreenplace.net/2010/09/18/python-internals-symbol-tables-part-1

Example from Racket:

;; Some programming languages allow the symbol table to be manipulated at run-time, so that symbols can be added at any time.

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