There are some cool features in M. One of the neatest is the ability to create arrays on the fly.

Ex:

  >set array("node1")="Hello"
  >set array("node1","subNode1")="Hola"
  >set array("node1","subNodeX")="Howdy"
  >set array("node2")=39481
  >set array(19849,1,1,1,3,"Godzilla",5,8)="Greetings"

All dynamically created on the fly - no need to define the array in any way ahead of time! The nodes are also automatically sorted after any addition/deletion.

Looping over the arrays is very easy too. M has a function that lets you set a variable to the next node.

Ex. (using the above example):

  >set foo=$O(array(foo)) - result: foo="node1"
  >set foo=$O(array(foo)) - result: foo="node2"
  >kill foo
  >set foo=$O(array(foo)) - result: foo="node1"
  >set bar=$O(array(foo,bar) - result: bar="subNode1"
  >set output=array(foo,bar) - result: output="Hello"
  >set bar=$O(array(food,bar) - result: bar="subNodeX"

Variables can also be created on the fly, and don't need to be defined as a type ahead of time. (Technically you don't define them ahead of time at all, if you want a new variable just set it to something!) They can be strings or numbers, and you can change their type at any time by setting them to a new value.

Pretty cool, and particularly easy for someone with no coding experience to pick up. I'd only ever use it for managing a database, though.