Import-Module functional

function map($f) {
  $reducer = {Param($a, $b) @($a) +  @(&$f $b)}
  @(@()) + $input | Compress-Object $reducer
}

function filter($f) {
  $reducer = {Param($a, $b) if (&$f $b) {@($a) + @($b)} else {$a}}
  @(@()) + $input | Compress-Object $reducer
}

$odd = {Param($a) $a % 2}
$square = {Param($a) $a * $a}
1..10 | map $square | filter $odd