Icon [http://www.cs.arizona.edu/icon/index.htm] is a programming
language with a long and rich history, although it is even more
obscure (''Since when is Tcl obscure?  -[FW]'') than tcl.

There are several points of similarity between the two languages,
along with many more differences.

   * Interpreted with a byte-code compiler
   * Portable across a range of different systems
   * Built-in memory allocation and garbage collection
   * Portable graphical tool kit
   * High degree of introspection
   * Rich built-in data structures (character sets, lists, records, sets, strings, tables)
   * Invocation of procedures based on a dynamic string value
   * Two memory scopes, global and local
   * Strongly typed values, but untyped variables
   * Primitives for determining if a variable has a value
   * No "go to" statement

The data structures are implemented in a way that allows a substantial
amount of polymophism.  The syntax for interating through all the values
in a set, or all the elements in a list, or even all the characters in
a string is pretty much the same.

Some of the differences are equally significant.

   * The syntax looks more like C than tcl
   * Many, many operators
   * Procedures can have local variables that are declared '''static''' instead of '''local''' so that they retain their values between invocations (for Tcl, see [Static variables])
   * No dynamic creation of procedures
   * No namespaces
   * Pattern matching is a normal extension of expression evaluation
   * Backtracking built into the language
   * Expressions can yield 0 or more values (not necessarily all at once)
   * Generators and co-expressions
   * Characters set limited to 8-bit characters
   * Separate compilation of procedures (not a just-in-time compiler)

''[escargo] 10/28-29/2002''
----

[Category Language]