fix: case is clause, not statement

Author: ktgw0316

src/content/1.9/function-types.tex

@@ -466,7 +466,7 @@ \subsection{Exponentials of Sums}
 that a function from a sum of two types is equivalent to a pair of
 functions from individual types. This is just the case analysis that we
 use when defining functions on sums. Instead of writing one function
-definition with a \code{case} statement, we usually split it into two
+definition with a \code{case} clause, we usually split it into two
 (or more) functions dealing with each type constructor separately. For
 instance, take a function from the sum type
 \code{(Either Int Double)}:

src/content/2.2/limits-and-colimits.tex

@@ -627,7 +627,7 @@ \section{Continuity}
 
 \src{snippet18}
 Indeed, any function of \code{Either b c} is implemented as a case
-statement with the two cases being serviced by a pair of functions.
+clause with the two cases being serviced by a pair of functions.
 
 Similarly, when we fix the first argument of the hom-set, we get the
 familiar reader functor. Its continuity means that, for instance, any

src/content/3.10/ends-and-coends.tex

@@ -368,7 +368,7 @@ \section{Coends}
 function must be prepared to handle any one of the types that may be
 encoded in the existential type. It's the same principle that tells us
 that a function that accepts a sum type must be implemented as a case
-statement, with a tuple of handlers, one for every type present in the
+clause, with a tuple of handlers, one for every type present in the
 sum. Here, the sum type is replaced by a coend, and a family of handlers
 becomes an end, or a polymorphic function.