chriskuech

# names of the dimensions in the order that we take the cross product
$crossProductOrder = "Category1", "Category2", "Category3"

# get the object's identity vector, as member of the cross product
function Get-Vector([psobject] $obj) {
  $crossProductOrder | % {$obj.$_}
}

# get the path to the object in the file system
function Get-VectorPath([psobject] $obj) {

chriskuech

# create the string identifier to describe the value within a dimension
# use `_` to describe when a value is not a member of a set
function Get-VectorComponent([psobject] $obj, [string] $dim) {
  $v = $obj.$dim
  @{$true = $v; $false = "_"}[$v -as [bool]]
}

# update Get-Vector to use Get-VectorComponent
function Get-Vector([psobject] $obj) {

chriskuech

# side effects
function square {
    $script:squared = $script:x * $script:x
}

# pure
function square($x) {
    $x * $x
}

chriskuech

# imperative
$myVar = $null
if ($x -gt 10) {
    $myVar = $true
} else {
    $myVar = $false
}

# declarative
$myVar = if ($x -gt 10) {$true} else {$false}

chriskuech

# iterative
function traverse($tree) {
    $stack = [System.Collections.Stack]::new()
    $stack.Push($tree)
    while ($stack.Count) {
        $node = $stack.Pop()
        if ($node.Left) {
            $stack.Push($node.Left)
        }
        if ($node.Right) {

chriskuech

# immutable read function (read the property directly)
function read($hash, $k) {
    $hash[$k]
}

# immutable write function (copy on write)
function write($hash, $k, $v) {
    $newHash = $hash.Clone()
    $newHash[$k] = $v
    $newHash

chriskuech

$add = {
  Param($a, $b)
  $a + $b
}

chriskuech

function add($a, $b) {
  $a + $b
}

$add = $function:add

chriskuech

$add = [scriptblock](Get-Content add.ps1 -Raw)
$add > add.ps1

chriskuech

$n = 14
function addToN($a) {
  $n = $a + $n
}

&$function:addToN 3
$n                  # `14`
.$function:addToN 3 
$n                  # `17`