Time for an 2014 update…

Task/Topic-variable/Forth/topic-variable-1.fth

@@ -0,0 +1 @@
+: myloop 11 1 do i . loop cr ; myloop

Task/Topic-variable/Forth/topic-variable-2.fth

@@ -0,0 +1,5 @@
+: ^2 dup * ;
+: sqrt 0 tuck ?do 1+ dup 2* 1+ +loop ;
+: topic >r r@ ^2 . r@ sqrt . r> drop ;
+
+23 topic

Task/Topic-variable/PicoLisp/topic-variable-1.l

@@ -0,0 +1,9 @@
+PicoLisp sets the value of the variable (symbol) '@' to the result of
+conditional and controlling expressions in flow- and logic-functions (cond, if,
+and, when, while, etc.).
+
+Within a function or method '@' behaves like a local variable, i.e. its value is
+automatically saved upon function entry and restored at exit.
+
+For example, to read the current input channel until EOF, and print the square
+of every item which is a number:

Task/Topic-variable/PicoLisp/topic-variable-2.l

@@ -0,0 +1,9 @@
+(while (read)
+   (when (num? @)
+      (println (* @ @)) ) )
+abc   # Not a number
+7     # Number
+49    # -> print square
+xyz   # Not a number
+3     # Number
+9     # -> print square