Changes between Version 30 and Version 31 of Fundamentals

Timestamp:

05/23/23 07:54:13 (3 years ago)

Author:

Alex Wilton

Comment:

Typo fix

Fundamentals

@@ -32 +32 @@
 Execution begins by spawning a process p0 to execute the root function. This causes scope 0 to be instantiated. An instance of a static scope is known as a ''dynamic scope'', or ''dyscopes'' for short. The dynamic scopes are represented by the ovals with double borders in Fig. 1(c). Each dyscope specifies a value for every variable declared in the corresponding static scope. In this case, the value 3 has been assigned to variable x.
 
-The state of process p0 is represented by a call stack (green). The entries on this stack are activation frames. Each frame contains two data: a reference to a dyscope (indicated by blue arrows) and a current location (or programmer counter vaule) in the static scope corresponding to that dyscope (not shown). The dyscope defines the environment in which the process evaluates expressions and executes statements. The currently executing function of a process, corresponding to the top frame in the call stack, can “see” only the variables in its dyscope and those of all the ancestors of its dyscope in the dyscope tree.
+The state of process p0 is represented by a call stack (green). The entries on this stack are activation frames. Each frame contains two data: a reference to a dyscope (indicated by blue arrows) and a current location (or programmer counter value) in the static scope corresponding to that dyscope (not shown). The dyscope defines the environment in which the process evaluates expressions and executes statements. The currently executing function of a process, corresponding to the top frame in the call stack, can “see” only the variables in its dyscope and those of all the ancestors of its dyscope in the dyscope tree.
 Returning to the example, p0 enters scope 6, instantiating that scope, and then spawns procedure `f`. This creates process p1, with a new stack with a frame pointing to a dyscope corresponding to static scope 1. The new process proceeds to run concurrently with p0. Meanwhile, p0 calls procedure `g`, which pushes a new entry onto its call stack, and instantiates scope 5. Hence p0 has two entries on its stack: the bottom one pointing to the instance of scope 6, the top one pointing to the instance of scope 5.