Changes between Version 11 and Version 12 of IR2

Timestamp:

04/19/21 15:42:08 (5 years ago)

Author:

siegel

Comment:

--

IR2

@@ -19 +19 @@
 * `$mem` : set of memory locations
 * `enum tag` : enumerated type
-* `struct tag` : structured type
+* `struct tag` : structured type, can also be used for "tuples"
 * `union tag` : union type
 * `T[]` : array of T
 * `void *` : pointer to anything
 * `T *` : pointer to T
-* `T(T1, ..., Tn)` : function consuming T1, ..., Tn and returning T
+* `T(T1, ..., Tn)` : function (aka procedure) consuming T1, ..., Tn and returning T
 * `$seq<T>` : sequence of T
 * `$set<T>` : set of T
@@ -31 +31 @@
 
 Notes
-* Sequences, sets, maps, and relations are mutable.  Is assignment by reference?
-* the difference between the array type and the sequence type is that elements of an array are addressable, i.e., one can form a pointer such as `&a[i]`.  This is not possible with sequences, sets, maps, or relations.
-* the difference between the function type and map type: a function is really a procedure in the language, so it can modify the state as well as return a value.   A map is a logical partial function: it is defined on some subset of the domain type, it will always "return" the save value on a given input, it cannot modify the state.
+* Sequences, sets, maps, and relations are immutable.   An assignment using objects of this type creates a new copy of the object, just as with primitive types like `int`.
+* The main difference between the array type and the sequence type is that elements of an array are addressable, i.e., one can form a pointer such as `&a[i]`.  This is not possible with sequences, sets, maps, or relations---there is no way to have a pointer to any component of such a type.
+* The difference between the function type and map type: a function is really a procedure in the language, so it can modify the state as well as return a value.    This is like the C notion of "function".   A map is a logical partial function: it is defined on some subset of the domain type, it will always "return" the same value on a given input, and reading it cannot modify the state.
 
 Questions