TCL

TCL is an imperative, interpreted, dynamically typed programming language. The Tool Command Language appeared in 1988. In Tcl, everything is a string.

It is probably best (and completely?) described by the 12 Rules for Tcl.

Basic Syntax by Example

Some nice comparisons of the syntax of many languages can be found at rigaux.org.

Hello World

set myVariable "Hallo World!"
puts $myVariable

Loop over a list

% foreach element {1 2 3} {
    puts $element
}

Fibonacci

proc fib {n} {
    if {$n < 2} {
        return $n
    } else {
        return [expr {[fib [expr {$n-2}]] + [fib [expr {$n-1}]]}]
    }
}

for {set x 0} {$x<10} {incr x} {
    puts [fib $x]
}

Comments

TCL uses # as a line comment and does not offer block comments. In fact, they recommend this:

if 0 {
    Any Tcl code to be commented out (with matching braces, of course!)
    or any other kind of text, will be ignored - and even [exit] won't fire
    because it's in braces, so left unevaluated!
}

Source: wiki.tcl.tk/1669

Logical operators

99 bottles of beer

#!/usr/bin/tclsh

# 99.tcl; Tcl version of 99 Bottles of Beer Song

proc findBString { count } {
  return [switch -exact -- $count {
    0       { expr {"No more bottles"}  }
    1       { expr {"1 bottle"}         }
    default { expr {"$count bottles"}   }
  }]
}

set bottles 99
set bString [findBString $bottles]
while {$bottles + 1} {
  puts "$bString of beer on the wall.  $bString of beer."
  incr bottles -1
  if {$bottles + 1} {
    set bString [findBString $bottles]
    puts "Take one down, pass it round, $bString of beer on the wall.\n"
  } else {
    puts "Go to the store and buy some more...99 bottles of beer."
  }
}

Source: 99-bottles-of-beer.net

Argument parsing

See itfParseArgv

Naming schemes

• Variables have to match the pattern [_a-zA-Z][_a-zA-Z0-9]*.
• Functions have to match the pattern [^ \t\n\r\f]+.
• Words in variable and function names are joined by camelCase or CamelCase.

Community

I think one indicator for the quality of the community is its size. And the community will grow when the language gets more popular.

According to Ohloh, TCL is quite unpopular:

You can also take a look at Google Trends:

• The TIOBE Index ranked Tcl at position 43 in March 2014.
• lang-index ranked Tcl at position 84 in the general category and at position 34 in the script category.
• There are 2,490 Tcl questions on Stack Overflow. Compare that to 286,244 questions about Python or 609,648 questions about Java.
• Tcl is ranked 18th on GitHub (source).

Execution Speed

Speed comparisons of programming languages are difficult. One nice way to compare the execution speed of programming languages is the benchmarksgame. But sadly, they don't have TCL.

Additional information

• Official website
• Wikipedia