6Environment

6.1Overview

Environment is a container to store maps associating symbols and values and maps associating symbols and value types.

Module, Class, and Object are all inherited from Environment.

scope problems

x = 0
if (true) {
    x = 3
}
println(x)

6.2Frame

Frame contains:

• value map
• value type map

Frame stack

Frame cache

Environment type:

• root
• local
• block
• class
• object
• lister

When the Interpreter starts, it runs with an Environment containing a frame of root type.

+-------------------+
|       root        |
+-------------------+

In a function call, the Interpreter creates a new Environment with cloned frames and pushes a new frame of local type.

+-------------------+
|      local        |
+-------------------+
|       root        |
+-------------------+

When a block is evaluated, the Interpreter creates a new Environment with cloned frames and pushes a frame of block type.

+-------------------+
|      block        |
+-------------------+
|       root        |
+-------------------+



+-------------------+
|      block        |
+-------------------+
|      local        |
+-------------------+
|      local        |
+-------------------+
|       root        |
+-------------------+


+-------------------+
|      class        |
+-------------------+
|       root        |
+-------------------+


+-------------------+
|      object       |
+-------------------+
|      class        |
+-------------------+
|       root        |
+-------------------+