In the explicit-control evaluator, how is a primitive function application handled at the `primitive_apply` label?
Explanation
To avoid getting bogged down in the details of implementing every primitive operation (like addition), the explicit-control evaluator abstracts this away. At the `primitive_apply` step, it uses a single, powerful machine operation called `apply_primitive_function` which is assumed to correctly apply the primitive function to the gathered arguments.
Other questions
According to the principles of designing a register machine, what are the two fundamental components that must be designed?
In the register machine designed to compute the greatest common divisor (GCD) using Euclid's Algorithm, what is the specific purpose of the register named 't'?
What data structure is identified as a crucial mechanism for implementing recursive processes, like the factorial function, on a register machine with a fixed number of components?
In the register machine for the recursive factorial function, which registers are explicitly saved on the stack before a recursive call is made?
The `make_new_machine` function constructs a basic machine model. According to Section 5.2.1, what two registers are initially included in this model's register table?
In the implementation of list-structured memory using vectors, how is a pointer to a pair represented?
What is the basic principle of the stop-and-copy garbage collection algorithm described in the chapter?
In the explicit-control evaluator, which register is used to hold the environment in which an evaluation is to be performed?
What feature of the explicit-control evaluator's design allows it to be tail-recursive?
What is the primary distinction between the execution strategies of interpretation and compilation as presented in the chapter?
Within the compiler's design, what does a linkage descriptor of 'return' signify for the generated code?
To support a more powerful subroutine mechanism, the register-machine language is extended. How is the `go_to` instruction modified to support this?
In the context of the stop-and-copy garbage collector, what is a 'broken heart'?
When the explicit-control evaluator is processing a conditional expression, why must the 'env' register be saved before evaluating the predicate?
In the compiled code for the recursive factorial function shown in Figure 5.17, what is the first instruction executed at the function's entry point, labeled 'entry1'?
How does the 'pair' operation get implemented in the register machine model that uses a vector-based memory with a 'free' register?
In the explicit-control evaluator, what is the purpose of the 'unev' register?
What is the primary efficiency advantage of compilation over interpretation as discussed in the text?
In the compiler's `preserving` function, when are `save` and `restore` instructions actually generated for a register?
What is the role of the `flag` register in the simulated register machine?
How is a `save(reg)` instruction implemented in the model where the stack is represented as a list pointed to by the `the_stack` register?
What is the role of the 'root' register in the stop-and-copy garbage collector?
In the controller for the recursive Fibonacci machine (Figure 5.12), why is the `val` register saved before the second recursive call (`go_to(label("fib_loop"))`) but not before the first?
How does the assembler, described in Section 5.2.2, resolve references to labels in the controller code?
In the compiler implementation, what three pieces of information are contained within an instruction sequence data structure?
How does the explicit-control evaluator handle the evaluation of a sequence of statements?
What is the key difference in how the compiler and the interpreter handle the function expression part of an application like `f(96, 22)` where `f` is a name?
In the stop-and-copy garbage collection algorithm, what is the purpose of the 'scan' pointer?
How does the explicit-control evaluator apply a compound (non-primitive) function?
According to footnote 37 in Section 5.5, why can the machine that runs compiled code be simpler than the interpreter machine?
What is the function of the `continue` register in the register machines described for implementing subroutines and recursion?
In the stop-and-copy garbage collector's main loop, what condition signals that the collection process is complete?
Why does the `compile_lambda_expression` function in the compiler generate code for the function body immediately after the code for constructing the function object?
What is the primary purpose of lexical addressing as a compiler optimization?
The assembler uses the function `extract_labels` to process the controller list. What two values does this function effectively return to its continuation (`receive`)?
According to the instruction summary in Section 5.1.5, which instruction is used to pop a value from the stack and place it into a register?
In the vector-based memory representation, what is used to distinguish a pointer to a pair from a pointer to a number or other data type?
When compiling a conditional expression, why does the `preserving` function save the `env` and `continue` registers around the code for the predicate?
What is the key functional difference between the register machine instructions `branch` and `go_to`?
In the explicit-control evaluator, how does the machine handle a return from a function if the function body terminates without executing a `return` statement?
How many registers are specified for the explicit-control evaluator machine described in Section 5.4?
What is the purpose of the `revert_stack_to_marker` instruction used in the explicit-control evaluator and compiler?
In the GCD machine with a user interface (Figure 5.4), what kind of instruction is used to handle printing the result?
When compiling the expression `f(g("x"), y)`, which registers must the compiler's `preserving` mechanism save around the code for the `g("x")` sub-expression?
In the design of the explicit-control evaluator, which two registers are used to hold the result of `scan_out_declarations` and the corresponding list of `*unassigned*` values during the evaluation of a block?
How many times will `vector_set` be called to implement the instruction `assign(reg1, list(op("pair"), reg(reg2), reg(reg3)))` in the vector-based memory model?
What is the key problem with implementing a recursive function like `factorial` by simply decrementing the `n` register and re-running the machine from the beginning?
In the context of interfacing compiled code with the evaluator, how is the evaluator modified to handle calls to compiled functions?
According to the analysis in Section 5.5.7, how did the number of stack pushes for computing factorial(5) compare between the interpreted and compiled versions?