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Annotation of researchv10no/cmd/sml/doc/refman/compat.tex, revision 1.1

1.1     ! root        1: \chapter{Compatibility}
        !             2: The language definition has changed a bit over the past year
        !             3: (1986--87), particularly in the area of exception syntax.  Some
        !             4: attempt has been made to allow old programs to continue running.
        !             5: \section{Exceptions}
        !             6: Three keywords: \verb"exceptionx", \verb"raisex", and \verb"handlex"
        !             7: are provided.  They implement the old-style exception mechanism, and
        !             8: are treated as derived forms.
        !             9: \begin{tabular}{@{}l l}
        !            10: \multicolumn{1}{c}{\bf Derived Form}&
        !            11: \multicolumn{1}{c}{\bf Equivalent Form} \\ \hline
        !            12: \verb"exceptionx" identifier & \verb"exception" Identifier \\
        !            13: \verb"exceptionx" identifier \verb":" ty & \verb"exception" Identifier \verb"of" ty \\
        !            14: 
        !            15: \verb"raisex" identifier & \verb"raise" Identifier \\
        !            16: \verb"raisex" identifier \verb"with" exp& \verb"raise" Identifier \verb"(" exp \verb")" \\
        !            17: 
        !            18: \verb"handlex" ident \verb"=>" exp & \verb"handle" Ident \verb"=>" exp \\
        !            19: \verb"handlex" ident \verb"=>" exp & \verb"handle" Ident () \verb"=>" exp \\
        !            20: 
        !            21: \verb"handlex" ident \verb"with" pat \verb"=>" exp & \verb"handle" Ident pat \verb"=>" exp \\
        !            22: \hline
        !            23: \end{tabular}
        !            24: 
        !            25: The derivations for \verb"handlex" are a bit more intricate than
        !            26: shown above.  The intent is that any program that works under the old
        !            27: scheme will continue to work if all instances of \verb"exception",
        !            28: \verb"handle", and \verb"raise" are changed to 
        !            29:  \verb"exceptionx", \verb"handlex", and \verb"raisex" respectively.
        !            30: 
        !            31: Note that the derived forms change the exception identifier in
        !            32: converting to the standard forms; they capitalize the first letter.
        !            33: This is to simulate the old scheme, in which exception names lived in
        !            34: a different space from value names.  This will cause problems in any
        !            35: programs with a capitalized value-name that happens to conflict with
        !            36: a (capitalized or uncapitalized) exception name.

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