Created
February 18, 2015 23:03
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PHP Streams
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<?php | |
// Now I remember why I don't use PHP anymore. | |
function repeat($n) { | |
return function() use ($n) { | |
return [$n, repeat($n)]; | |
}; | |
} | |
function countFrom($n) { | |
return function() use ($n) { | |
return [$n, countFrom($n+1)]; | |
}; | |
} | |
function mapOn($s, $fn) { | |
return function() use ($s, $fn){ | |
list($head, $tail) = $s(); | |
return [$fn($head), mapOn($tail, $fn)]; | |
}; | |
} | |
function take($s, $n) { | |
if($n <= 0) { | |
return []; | |
} | |
list($head, $tail) = $s(); | |
$arr = take($tail, $n-1); | |
array_unshift($arr, $head); | |
return $arr; | |
} | |
function combine($s1, $s2, $fn) { | |
return function() use ($s1, $s2, $fn) { | |
list($h1, $t1) = $s1(); | |
list($h2, $t2) = $s2(); | |
return [$fn($h1, $h2), combine($t1, $t2, $fn)]; | |
}; | |
} | |
$test1 = countFrom(1); | |
$test2 = mapOn($test1, function($n) { | |
return $n+$n; | |
}); | |
$test3 = combine($test1, $test2, function($x, $y) { | |
return $x + $y; | |
}); | |
echo "\n\tTest 1\n"; | |
foreach(take($test1, 5) as $i) { | |
echo $i."\n"; | |
} | |
echo "\n\tTest 2\n"; | |
foreach(take($test2, 5) as $i) { | |
echo $i."\n"; | |
} | |
echo "\n\tTest 3\n"; | |
foreach(take($test3, 20) as $i) { | |
echo $i."\n"; | |
} |
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