@@ -889,11 +889,10 @@ \subsection{Natural numbers}\index[concept]{natural number}
889889\end {coq }
890890\coqrun {name=larger_than4_run}{ssr,larger_than4}
891891
892- On the other hand, if we want to describe a different computation for
893- three different cases and use variables in more than one case, we
894- must either awkwardly nest several `` \C {if .. then .. else}'' blocks
895- inside each other, or (better) use the more general
896- `` \C {match .. with .. end}'' syntax. Here is an example:
892+ The `` \C {if .. then .. else}'' syntax is just a particular case
893+ of the more general `` \C {match .. with .. end}'' construct,
894+ which allows us to separate several (not just two) cases.
895+ Here is an example:
897896
898897\begin {coq }{name=awkward5}{}
899898Definition three_patterns n :=
@@ -977,7 +976,7 @@ \subsection{Natural numbers}\index[concept]{natural number}
977976Definition same_bool b1 b2 :=
978977 match b1 with
979978 | true => match b2 with true => true | _ => false end
980- | false => match b2 with false => true | _ => false end
979+ | false => match b2 with true => false | _ => true end
981980 end.
982981\end {coq }
983982\coqrun {name=awk7_run}{ssr,awkward7}
@@ -1321,7 +1320,7 @@ \section{Containers}\label{sec:poly}
13211320
13221321As expected, \C {listn} % elements of this data type
13231322cannot hold boolean values.
1324- So, if we need to manipulate a list of booleans,
1323+ So if we need to manipulate a list of booleans
13251324we have to define a similar data type:
13261325\C {listb}.
13271326
@@ -1386,7 +1385,7 @@ \subsection{The (polymorphic) sequence data type}
13861385
13871386
13881387The name \C {seq} refers to (finite) `` sequences'' , also called
1389- `` lists'' . This definition describes the type
1388+ `` lists'' . This definition actually describes the type
13901389of lists as a {\em polymorphic type}. This means that there is a
13911390different type \C {(seq A)} for each possible choice of type \C {A}. For example
13921391\C {(seq nat)} is the type of sequences of natural numbers, while
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