Changeset 423c0cd

Timestamp:

Mar 12, 2024, 3:14:47 PM (9 months ago)

Author:

Peter A. Buhr <pabuhr@…>

Branches:

master

Children:

8bdc9705, a3525c4

Parents:

9a32903

Message:

more updates on OCaml

File:

• doc/theses/jiada_liang_MMath/relatedwork.tex (modified) (2 diffs)

doc/theses/jiada_liang_MMath/relatedwork.tex

@@ -2502 +2502 @@
 \end{ocaml}
 
-A variant type can have a recursively definition.
+A variant type can have a recursive definition.
 \begin{ocaml}
 type stringList = Empty | Pair of string * stringList
@@ -2509 +2509 @@
 A recursive function is often used to pattern match against a recursive variant type.
 \begin{ocaml}
-let rec len_of_string_list(l: stringList): int =
-        match l with
+let rec len_of_string_list( list : stringList ): int =
+        match list with
                 Empty -> 0 |
-                Pair(_ , r) -> 1 + len_of_string_list r
+                Pair( _ , r ) -> 1 + len_of_string_list r
 \end{ocaml}
-
-Note, matching is logically a dynamic type-check.
-Hence, a tagged variant has no notion of enumerabilty, and therefore is not an enumeration, except for the simple pure (untyped) case.
+Here, the head of the recursive type is removed and the remainder is processed until the type is empty.
+Each recursion is counted to obtain the number of elements in the type.
+
+Note, the compiler statically guarantees that only the correct kind of type can be used in the \lstinline[language=ML]{match} statement.
+However, the tag is dynamically set on binding (and possible reset on assignment), so the \lstinline[language=ML]{match} statement is effectively doing RTTI to select the matching case clause.
+Hence, a tagged variant has no notion of enumerabilty, and therefore is not a real enumeration, except for the simple pure (untyped) case.