WolframLang: Local Variable

• To create local variables, use Module.
• To create local constants, use With.

Module[{var1, var2 etc}, body]

• Eval body with temp local variables.
• Each of the variable var can be the form var = val or you can set the value in the body by var = val
• Return the value of body.

Module

(this is similar to “lexical scoped” construct in most programing languages, or lisp's let)

When the body is more than one expression, add semicolon between them. [see CompoundExpression and Semicolon]

x = 5;

Module[{x},
 x = 3;
 x+1] == 4

x == 5
(* x is still 5 *)

Module[{x = 3}, x+1] == 4

Later values in variable is not available:

Module[{x=2, y=x}, y] =!= 2

To assign variable that depends on previous variable value, put the assignment in body:

Module[{x=2, y},
y=x;
y] == 2