Some notes to self of things I found interesting:
the environment
I like the idea of giving more thought to the environment itself. I’ve always thought more about the code, less about what the environment is doing.
the interpreter must maintain some sort of memory that keeps track of the name-object pairs. This memory is called the environment.
the general notion of the environment as providing a context in which evaluation takes place will play an important role in our understanding of program execution.
evaluation
Tree accumulation – a new concept to me. I like trees as structures.
In general, we shall see that recursion is a very powerful technique for dealing with hierarchical, treelike objects. In fact the “percolate values upward” form of the evaluation rule is an example of a general kind of process known as tree accumulation
special forms
Read about special forms before, but it kind of clicked here to read that they are exceptions to general evaluation and have their own rules.
Such exceptions to the general evaluation rule are called special forms.
defineis the only example of a special form that we have seen so far, but we will meet others shortly. Each special form has its own evaluation rule.
applicative-order evaluation vs normal-order evaluation
You can evaluate procedures in different ways.
I think there’s a subtle disctinction beween evaluation and procedure application that I’ve missed and need to look back over.
That’ll do for now!