+.so tmac.tr
+.sv |1.25i
+.de Ip
+.IP \(bu \w'\(bu'u+1n
+..
+.LP
+.ce 10
+\f3Version 5.9 of Icon\fR
+.sp 2
+Ralph E. Griswold, Robert K. McConeghy, and William H. Mitchell
+.sp
+August 22, 1984
+.ce 0
+.sp 1
+.PP
+Version 5.9 of Icon is a modification of Version 5.8 of Icon.
+The \*U implementation runs on both PDP-11s and VAXs. This document
+is a brief summary of Version 5.9. See also References 1, 2, and 3.
+.Un
+.SH
+Changes
+.LP
+.in 5n
+.Ip
+An optional language extension provides sets as a built-in data type [3].
+.Ip
+The Icon compiler has been deleted, leaving only the interpreter.
+A ``personalized interpreter'' facility has been added to allow individuals to maintain
+customized versions of the Icon run-time system [5].
+This facility replaces the former use of
+external functions with the Icon compiler to augment the function
+repertoire of Icon.
+.Ip
+The implementation of the table data type has been redone to
+increase the efficiency of table lookup.
+.Ip
+There is a new keyword, \*M&options\fR, whose value is a string listing
+the options used for installing Icon at the local site [3, 4].
+.Ip
+Considerable work has been done throughout the Icon system to
+improve the quality of the code and to remove nonportable
+constructs.
+.Ip
+The source code has been commented extensively.
+.Ip
+A number of minor bugs have been fixed.
+.Ip
+The Icon program library has beed reorganized and new material has been
+added to it [6].
+.Ip
+The Icon distribution hierarchy has been reorganized and new material
+has been added to aid in testing and porting to new computers [4].
+.in 0
+.SH
+User Impacts
+.LP
+.in 5n
+.Ip
+Persons who formerly used the Icon compiler with external functions
+will need to convert to personalized interpreters.
+.Ip
+The internal organization of tables is different from earlier
+implementations. For example, if
+\*Mt\fR is a table,
+the order of elements generated by \*M!t\fR generally is different from before.
+Similarly, the value of \*M?t\fR is likely to be different.
+.Ip
+The functionality of some components of the Icon program library
+has been changed.
+.in 0
+.bp
+.SH
+Known Bugs
+.PP
+This list ennumerates all known bugs in Version 5.8 of Icon.
+If you find a bug that is not in this list, please contact us.
+.LP
+.in 5n
+.Ip
+The translator does not detect arithmetic overflow in conversion of
+numeric literals. Very large numeric literals may have incorrect values.
+.Ip
+Integer overflow on multiplication and exponentiation are not detected
+during execution.
+This may occur during type conversion.
+.Ip
+Line numbers may be wrong in diagnostic messages related to lines with continued
+quoted literals.
+.Ip
+In some cases, trace messages may show the return of subscripted
+values, such as \*M&null\^[2]\fR, that would be erroneous if they were
+dereferenced.
+.Ip
+File names are truncated to 14 characters by some versions of UNIX. If such a truncation
+deletes part of the terminating \*M.icn\fR of a file that
+is input to the translator,
+mysterious diagnostic
+messages may occur during linking.
+.Ip
+On PDP-11s, list blocks can contain no more than 4090 elements. List
+blocks are created when the \*Mlist()\fR function is called, when
+literal lists are specified, and when the \*Msort()\fR function
+converts a table into a list. It should be noted that it is possible
+for a list to grow to beyond 4090 elements; the limitation is only
+upon the size of the list when it is created.
+.Ip
+There is a bug in the 4.1bsd \*Mfopen()\fR routine that under certain
+conditions returns a \*MFILE\fR pointer that is out of range when
+one tries to open too many files.
+On systems where this bug is present, it may manifest itself in the form of
+run-time Error 304 when one tries to open too many files.
+(On 4.1bsd systems this limit is usually 20 files.)
+.Ip
+If one has an expression such as \*Mx := create \*(El \fR in a loop, and
+\*Mx\fR is not a global variable, the unreferenceable expression stacks
+generated by each successive \*Mcreate\fR operation are not
+garbage collected. This problem can be circumvented
+by making \*Mx\fR a global variable or by assigning a value to \*Mx\fR before
+the \*Mcreate\fR operation, e.g., \*Mx := &null; x := create \*(El \fR.
+.Ip
+Overflow of a co-expression stack due to excessive recursion is not detected
+and may cause mysterious program malfunction.
+.Ip
+Program malfunction may occur if \*Mdisplay()\fR is used in a co-expression.
+.Ip
+The garbage collector was designed for machines with small
+address spaces and as such is not well-suited for
+machines like the VAX. No empirical studies have been made,
+but it is suspected that performance of the garbage collector
+could be improved substantially on the VAX. In particular, if
+the user attempts to create a very large data object that will
+not fit into memory, (such as a million-element list), it takes
+the system an inordinately long time to determine that the object can
+not be allocated.
+.in 0
+.SH
+References
+.LP
+1. Griswold, Ralph E. \fIAn Overview of the Icon Programming Language\fR.
+Technical Report TR 83-3a, Department of Computer Science, The
+University of Arizona. May 1983.
+.LP
+2. Griswold, Ralph E. and Madge T. Griswold.
+\fIThe Icon Programming Language\fR. Prentice-Hall Inc., Englewood
+Cliffs, New Jersey. 1983.
+.LP
+3. Griswold, Ralph E., Robert K. McConeghy, and William H. Mitchell. \fIExtensions
+to Version 5 of the Icon Programming Language\fR.
+Technical Report TR 84-10a,
+Department of
+Computer Science, The University of Arizona.
+August 1984.
+.LP
+4. Griswold, Ralph E. and William H. Mitchell. \fIInstallation and
+Maintenance Guide for Version 5.9 of Icon\fR, Technical Report
+TR 84-13, Department of Computer Science, The University of
+Arizona. August 1984.
+.LP
+5. Griswold, Ralph E., Robert K. McConeghy, and William H. Mitchell.
+\fIPersonalized Interpreters for Icon\fR. Technical Report TR 84-14,
+Department of Computer Science, The University of Arizona. August 1984.
+.LP
+6. Griswold, Ralph E. \fIThe Icon Program Library\fR. Technical Report
+TR 84-12, Department of Computer Science, The University of Arizona.
+August 1984.
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