doc-src/TutorialI/Recdef/document/examples.tex

 Here is a simple example, the \rmindex{Fibonacci function}:%
 \end{isamarkuptext}%
 \isacommand{consts}\ fib\ {\isacharcolon}{\isacharcolon}\ {\isachardoublequote}nat\ {\isasymRightarrow}\ nat{\isachardoublequote}\isanewline
 \isacommand{recdef}\ fib\ {\isachardoublequote}measure{\isacharparenleft}{\isasymlambda}n{\isachardot}\ n{\isacharparenright}{\isachardoublequote}\isanewline
 \ \ {\isachardoublequote}fib\ {\isadigit{0}}\ {\isacharequal}\ {\isadigit{0}}{\isachardoublequote}\isanewline
-\ \ {\isachardoublequote}fib\ {\isadigit{1}}\ {\isacharequal}\ {\isadigit{1}}{\isachardoublequote}\isanewline
+\ \ {\isachardoublequote}fib\ {\isadigit{1}}{\isacharprime}\ {\isacharequal}\ {\isadigit{1}}{\isachardoublequote}\isanewline
 \ \ {\isachardoublequote}fib\ {\isacharparenleft}Suc{\isacharparenleft}Suc\ x{\isacharparenright}{\isacharparenright}\ {\isacharequal}\ fib\ x\ {\isacharplus}\ fib\ {\isacharparenleft}Suc\ x{\isacharparenright}{\isachardoublequote}%
 \begin{isamarkuptext}%
 \noindent
 \index{measure functions}%
 The definition of \isa{fib} is accompanied by a \textbf{measure function}