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0 pointschriswarbo11y ago0 comments

Parameter order is an important part of a function's interface. In particular, commonly-used arguments should occur before call-site-specific arguments, so that we can specialise the function. array_map gets this right:

    $asBools = partial_apply('array_map', 'boolval');

    $asBools(['hello', '', 'world']) === [true, false, true]
    $asBools([-2, -1, 0, 1, 2]) === [true, true, false, true, true]

array_filter and array_reduce get this wrong, requiring awkward argument-shuffling:

    $inverseFilter = partial_apply(flip('filter'), 'boolNot');

    $inverseFilter([-2, -1, 0, 1, 2]) === [2 => 0]
    array_keys($inverseFilter(['foo' => true, 'bar' => false])) === ['bar']

    $allTrue = partial_apply(flip(partial_apply(flip('array_reduce'), 'boolAnd')), true);

    $allTrue(['hello', 'world']) === true
    $allTrue([true, true, 0, true]) === false

Note that a) if specialisation was easy, there would be no need for default arguments and b) having default arguments at the end is exactly the wrong way around for making specialisation not suck.

We could sweep this under the rug by saying it's awkward because it's not idiomatic PHP; but one reason why it's not idiomatic is that it's awkward!

Just look at Javascript, where functions are slightly less awkward; there are lots of functional APIs in wide use, eg. Underscore.

$inverseFilter = partial_apply(flip('filter'), 'boolNot'); $inverseFilter([-2, -1, 0, 1, 2]) === [2 => 0] array_keys($inverseFilter(['foo' => true, 'bar' => false])) === ['bar'] $allTrue = partial_apply(flip(partial_apply(flip('array_reduce'), 'boolAnd')), true); $allTrue(['hello', 'world']) === true $allTrue([true, true, 0, true]) === false

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6 comments · 1 top-level

jules11y ago· 5 in thread

The far greater wart is passing functions as string names. PHP is so bad that it's hard to imagine that it isn't a giant troll. No amount of modernizing will ever turn PHP into anything close to sane; the amount and depth of craziness is simply too huge.

donatj11y ago

I feel like its callable system is simple, easy to use, and frankly awesome.

I can do $func = ['object', 'staticMethodName'];

$func = [$instance, 'publicMethodName'];

$func = 'functionName';

$func = '\namespaced\functionName';

$func = function(){ ... };

$func = $callableObject; // ( http://php.net/manual/en/language.oop5.overloading.php#objec... )

I can execute any of the above by calling `$func('doIt');`

Moreover all of those will all pass a `callable` typehint on a method call as well as the is_callable if they exist and are callable. Its quite powerful.

jules11y ago

The problem is that a function is a thing. A string is a different thing. Imagine if arrays were represented as comma delimited strings, and you had a function isArray to check if a string has the right format to represent an array. That would be ridiculous right? An array should be its own type. The same goes for functions. Representing functions as string names is just as crazy as representing arrays as comma delimited strings.

Though who am I kidding, PHP is also confused between numbers and arrays and strings, so I guess at least it's consistent that the language is thoroughly crazy.

1 more reply

wvenable11y ago

A lot of languages have ways of calling functions and methods by string names -- PHP just makes it very easy and the design is actually really clean.

chriswarboOP11y ago

> PHP just makes it very easy and the design is actually really clean.

Very little about PHP's treatment of functions is easy or clean.

    function foo() { echo "Hello world"; }

    $w = 'foo';
    echo $w;  // foo
    $w();     // Hello world
    'foo'();  // PHP Parse error: syntax error, unexpected '('

    function bar() { return 'foo'; }
    $x = bar();
    echo $x;  // foo
    $x();     // Hello world
    bar()();  // PHP Parse error:  syntax error, unexpected '('

    $o = new stdClass;
    $o->baz = 'foo';
    $y = $o->baz;
    echo $y;  // foo
    $y();     // Hello world
    $o->baz();  // PHP Fatal error:  Call to undefined method stdClass::baz()

Heck, PHP doesn't even recognise function-call syntax applied to a function!

    $z = function() {
           echo "Hello world";
         };
    $z();  // Hello world
    (function() {
       echo "Hello world";
     })();  // PHP Parse error:  syntax error, unexpected '('

1 more reply

TazeTSchnitzel11y ago

That's something I'm working on by adding function references. Not sure if it'll be accepted.

j / k navigate · click thread line to collapse

0 comments

6 comments · 1 top-level

jules11y ago· 5 in thread

donatj11y ago

I feel like its callable system is simple, easy to use, and frankly awesome.

I can do $func = ['object', 'staticMethodName'];

$func = [$instance, 'publicMethodName'];

$func = 'functionName';

$func = '\namespaced\functionName';

$func = function(){ ... };

$func = $callableObject; // ( http://php.net/manual/en/language.oop5.overloading.php#objec... )

I can execute any of the above by calling `$func('doIt');`

Moreover all of those will all pass a `callable` typehint on a method call as well as the is_callable if they exist and are callable. Its quite powerful.

jules11y ago

Though who am I kidding, PHP is also confused between numbers and arrays and strings, so I guess at least it's consistent that the language is thoroughly crazy.

1 more reply

wvenable11y ago

A lot of languages have ways of calling functions and methods by string names -- PHP just makes it very easy and the design is actually really clean.

chriswarboOP11y ago

> PHP just makes it very easy and the design is actually really clean.

Very little about PHP's treatment of functions is easy or clean.

    function foo() { echo "Hello world"; }

    $w = 'foo';
    echo $w;  // foo
    $w();     // Hello world
    'foo'();  // PHP Parse error: syntax error, unexpected '('

    function bar() { return 'foo'; }
    $x = bar();
    echo $x;  // foo
    $x();     // Hello world
    bar()();  // PHP Parse error:  syntax error, unexpected '('

    $o = new stdClass;
    $o->baz = 'foo';
    $y = $o->baz;
    echo $y;  // foo
    $y();     // Hello world
    $o->baz();  // PHP Fatal error:  Call to undefined method stdClass::baz()

Heck, PHP doesn't even recognise function-call syntax applied to a function!

    $z = function() {
           echo "Hello world";
         };
    $z();  // Hello world
    (function() {
       echo "Hello world";
     })();  // PHP Parse error:  syntax error, unexpected '('

1 more reply

TazeTSchnitzel11y ago

That's something I'm working on by adding function references. Not sure if it'll be accepted.

j / k navigate · click thread line to collapse