-What we did in Monday's seminar:
+What we did in Monday's seminar
+-------------------------------
We start with a simulation of semantic composition:
This is shorthand for the same thing. Just trust me on that.
What's going on here?
+=====================
`(cons M N)` is a request to build an ordered pair out of the values M and N.
Scheme displays that pair as `'(M . N)` You can't write `(M . N)` yourself and expect Scheme to understand that you're talking about this pair. If you tried, to, Scheme would think you're trying to apply the function M to some arguments, which you're not, and also
'((the . man) . (read . (the . book)))
-Although there aren't `'`s prefixed to each of the elements of this nested structure, those elements are still the `'the`, `'man` and so on primitive atomic values that we specified. Not the values (if any) possessed by some variables `the`, `man`, and so on.
+---or as an equivalent shorthand. And although there aren't `'`s prefixed to each of the elements of this nested structure, those elements are still the `'the`, `'man` and so on primitive atomic values that we specified. Not the values (if any) possessed by some variables `the`, `man`, and so on.
We can think of this nested structure of pairs as the tree:
We start by defining `damn` as a "thunk" that when applied to zero arguments returns a trivial adjectival meaning, which we'll designate with the primitive symbol `'id`.
What's a "thunk"?
+=================
Remember, in Scheme you can have functions that take one value, and also functions that take two values, and also functions that take zero values. The last ones are called "thunks." The thunk is not identical to the value it returns. For instance: