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Gregg M. Townsend
Department of Computer Science
The University of Arizona
www.cs.arizona.edu/icon/v942/relnotes.htm
Last updated April 9, 2003
Version 9.4.2 of Icon is a minor update to version 9.4.1 of Icon. The 256-color graphics limit has been removed, and a configuration for Cygwin (on Windows) has been added. Some minor bugs have been fixed.
The Icon language is unchanged, and this Unix implementation remains compatible at the source level with Icon 9.3 for Windows.
Notable changes in this latest version are listed here. Some code cleanup work and documentation editing has also been done.
Icon's X-windows interface previously limited each window
to 256 colors at one time.
This limitation has been removed for the TrueColor displays
provided by most modern computers.
Median-cut quantization is used to select 256 image colors
when WriteImage() is called to write a GIF file.
A new configuration allows Icon to be built on the Cygwin Unix environment for Microsoft Windows. For more details see Icon on Cygwin.
As usual, several files in the Icon program library have been added or edited. The core library files, however, remain stable.
Many changes were made to the pattern and weaving packages. Other notable changes include:
procs/cartog add sbsize() for creating scale bars procs/pscript add psprotect() for escaping PostScript strings procs/lists add lst2str() to convert list to string procs/pdco add an "undulant" PDCO procs/random use /dev/random, if available, in randomize() procs/records add "move corresponding" procedure mvcorr(R1, R2) procs/seqops add sconcatp() and splacep() procs/string add procedures for finding common prefix or suffix gprocs/mapnav repackage the map navigation GUI from gprogs/dlgvu gprocs/vtext don't let PgUp etc. insert garbage in text fields progs/htget send Host: spec for use with multi-domain servers progs/shuffle new utility for reordering lines of a file gprogs/dlgvu read labels; write locations; add PostScript scalebar gprogs/gallery better coloring, more formats, snapshot command gprogs/histo save histogram image to a GIF file gprogs/trkvu new program for viewing GPS track logs cfuncs/ilists.c new support code for array access by loadable functions
icon – [args]"
can now be used to execute a source program read from standard input.
icont –N" flag suppresses
embedding of an iconx path in the generated executable
HEAPSIZE and
BLOCKSIZE no longer function as
undocumented alternatives to BLKSIZE.
The GNU ls utility uses BLOCKSIZE
for other purposes, leading to confusion.
make Install" has been changed to never delete anything.
It now creates a new directory rather than altering an existing one.
New features added since the publication of the Icon books are described below.
An Icon source file can be made executable under Unix by prefixing it with a comment line
#!/usr/bin/env iconicon command,
which in another form allows a small Icon program to be embedded
within a shell script.
See the man page for details.
The traditional icont command
remains available for less specialized purposes.
Under Unix, colons (:) may now separate directories in the
LPATH and IPATH environment variables as an
alternative to spaces.
The Icon translator and linker search these paths when looking for
$include and link files respectively.
The Icon program library is now searched automatically, but
LPATH and IPATH can still be set to control
the search order.
For version 9.4, the effective path in each case is:
Other changes affect the configuration of Icon at installation time and the way executable Icon programs locate the interpreter. These changes, which are transparent to most users, are discussed in more detail on the File Organization page.
The files in a directory can be listed by opening the directory as a file.
Subsequent reads return the names of the files contained in the directory.
The names are returned in no particular order, and for Unix, the directories
"." and ".." are included.
The function read() recognizes
three kinds of line terminators when reading a file
opened in translated mode:
Windows (CR+LF), Macintosh (CR), or Unix (LF).
Consequently, text files created on one platform can be
read by an Icon program running on a different platform.
Large integers cannot be used with i to j,
with seq(), or with integer-valued keywords.
Large-integer literals are constructed at run-time, so such literals are best kept outside of loops.
Conversion of a large integer to a string is quadratic in the length of the integer. Conversion of a very large integer may take a long time.
Stack overflow checking uses a heuristic that is not always effective. Stack overflow in a co-expression is especially likely to escape detection and cause a mysterious program malfunction.
If an expression such as
x := create expr
is used in a loop, and x is not a global variable,
uncollectable co-expressions accumulate with each iteration.
This problem can be circumvented by making x
a global variable or by assigning a value to x
before the create operation, as in
x := &null
x := create expr
Integer overflow on exponentiation may not be detected during execution. Such overflow may occur during type conversion.
See the documentation guide for an overview of the available Icon documentation.
For installation instructions, see Installing Binaries or Building from Source as appropriate.
Frank Lhota contributed the Cygwin port.
Ralph Griswold contributed a large number of program library changes.
Frank Glandorf contributed dlgvu modifications.
Kostas Oikonomou contributed the array support code.
Christian Hudon helped with testing.