[RFC] Global functions any() and all() on iterables View as Markdown

This would be a fantastic addition, and it would also alleviate an issue in
static analysis land where it's very tricky (in the general case) to verify
exactly what implications successfully completing a given foreach loop has
on the array being iterated over (e.g.
https://github.com/vimeo/psalm/issues/649).

Using this function would make user intent much clearer to static analysis
tools, and also (as RFC describes) increase code legibility.

Hi internals,

I've created an RFC for https://wiki.php.net/rfc/any_all_on_iterable

This was proposed 2 days ago in https://externals.io/message/111711 with
some interest
("Proposal: Adding functions any(iterable $input, ?callable $cb = null,
int $use_flags=0) and all(...)")

• The $use_flags parameter was removed

The primitives any() and all() are a common part of many programming
languages and help in avoiding verbosity or unnecessary abstractions.

https://hackage.haskell.org/package/base-4.14.0.0/docs/Prelude.html#v:any

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some

• https://docs.python.org/3/library/functions.html#all

https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#allMatch-java.util.function.Predicate-

For example, the following code could be shortened significantly

// Old version
$satisifes_predicate = false;
foreach ($item_list as $item) {
    if (API::satisfiesCondition($item)) {
        $satisfies_predicate = true;
        break;
    }
}
if (!$satisfies_predicate) {
    throw new APIException("No matches found");
}

// New version is much shorter and readable
if (!any($item_list, fn($item) => API::satisfiesCondition($item))) {
    throw new APIException("No matches found");
}

That example doesn't have any suitable helpers already in the standard
library.
Using array_filter would unnecessarily call satisfiesCondition even after
the first item was found,
and array_search doesn't take a callback.

A proposed implementation is https://github.com/php/php-src/pull/6053 -
it takes similar flags and param orders to array_filter().

Thanks,

• Tyson
  --

To unsubscribe, visit: https://www.php.net/unsub.php

On Tue, Sep 1, 2020 at 1:56 AM tyson andre tysonandre775@hotmail.com
wrote:

Hi internals,

I've created an RFC for https://wiki.php.net/rfc/any_all_on_iterable

This was proposed 2 days ago in https://externals.io/message/111711 with
some interest
("Proposal: Adding functions any(iterable $input, ?callable $cb = null,
int $use_flags=0) and all(...)")

• The $use_flags parameter was removed

The primitives any() and all() are a common part of many programming
languages and help in avoiding verbosity or unnecessary abstractions.

https://hackage.haskell.org/package/base-4.14.0.0/docs/Prelude.html#v:any

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some

• https://docs.python.org/3/library/functions.html#all

https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#allMatch-java.util.function.Predicate-

For example, the following code could be shortened significantly

// Old version
$satisifes_predicate = false;
foreach ($item_list as $item) {
    if (API::satisfiesCondition($item)) {
        $satisfies_predicate = true;
        break;
    }
}
if (!$satisfies_predicate) {
    throw new APIException("No matches found");
}

// New version is much shorter and readable
if (!any($item_list, fn($item) => API::satisfiesCondition($item))) {
    throw new APIException("No matches found");
}

That example doesn't have any suitable helpers already in the standard
library.
Using array_filter would unnecessarily call satisfiesCondition even after
the first item was found,
and array_search doesn't take a callback.

A proposed implementation is https://github.com/php/php-src/pull/6053 -
it takes similar flags and param orders to array_filter().

Thanks,

• Tyson

To be in line with naming conventions, I would suggest calling these
iter_any() and iter_all(), using iter_* as the prefix for our future
additions to the "functions that work on arbitrary iterables" space.
iterable_any() and iterable_all() would work as well, though are
unnecessarily verbose.

Regards,
Nikita

Hi internals,

I've created an RFC for https://wiki.php.net/rfc/any_all_on_iterable

Hi Andre,

I like the RFC, it is small and the added value is clear. The RFC
mentions the possibility of adding a first() method in the future. I
think it would be great to generalize this to the very thing that
excites me most about this RFC: It could be the starting point for
ultimately arriving at a better set of tools for working with iterables.

There is some discussion about the need for functions that work on keys
in stead of values or on both keys and values. It was suggested to
introduce option flags. It was also suggested to change the function
names to allow introducing multiple variants in the future:

all_values()
all_keys()

However, as Larry already hinted at, we may be able to do better. If we
introduce a keys() function that generates the keys from a given
iterable then we can use any value oriented function to work with the
keys in stead.

There is also the case where both the keys and values are relevant. It
may be interesting to look at how Python handles this (I'm sorry, I just
happen to know that language well). Python has dictionaries.
Dictionaries have an items() method. This method is one of the most
commonly used methods in Python. It is a generator that yields key/value
pairs, one pair for each item in the dictionary.

Perhaps we could do the same thing by introducing an items() function
that takes an iterable and yields one array for each item in the
iterable. The arrays contain the key/value pairs. Quoting the example
Tyson gave:

any($itemMap, fn($enabled, $itemId) => $enabled &&
meetsAdditionalCondition($itemId), ARRAY_FILTER_USE_BOTH)

Using items(), the above can also be written as:

any(items($itemMap), fn($item) => $item[0] &&
meetsAdditionalCondition($item[1]))

This way we can do with just one any() variant and without option flags.
It makes the example slightly less descriptive though, trading variable
names for array indices. In Python I would probably use a comprehension
here. Maybe the following will be possible in PHP at some point:

any(foreach $itemMap as $enabled => $itemId yield $enabled &&
meetsAdditionalCondition($itemId))

Regards,
Dik Takken

On Mon, Aug 31, 2020 at 6:56 PM tyson andre tysonandre775@hotmail.com
wrote:

I've created an RFC for https://wiki.php.net/rfc/any_all_on_iterable

I've probably reached this thread too late, but I'm going to throw out my
old chestnut that these things don't belong in the engine. They belong in
userspace.

1. Instant forward compatibility (any version can run composer install)
2. Instant bug fixes and improvements (no waiting for the next minor
   version of PHP)
3. Better visibility from the JIT (not having to cross userspace/internals
   border is good)

And that's all I'm going to say because I'm pretty sure I've lost the
argument long ago, but here's my any/all/none (and other) methods from
years ago (IN USERSPACE!):
https://github.com/phplang/generator/blob/master/src/iterable.php

-Sara

Hi internals,

I've created an RFC for https://wiki.php.net/rfc/any_all_on_iterable

This was proposed 2 days ago in https://externals.io/message/111711 with some interest
("Proposal: Adding functions any(iterable $input, ?callable $cb = null, int $use_flags=0) and all(...)")

• The $use_flags parameter was removed

The primitives any() and all() are a common part of many programming languages and help in avoiding verbosity or unnecessary abstractions.

- https://hackage.haskell.org/package/base-4.14.0.0/docs/Prelude.html#v:any
- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some
- https://docs.python.org/3/library/functions.html#all
- https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#allMatch-java.util.function.Predicate-

For example, the following code could be shortened significantly

// Old version
$satisifies_predicate = false;
foreach ($item_list as $item) {
    if (API::satisfiesCondition($item)) {
        $satisfies_predicate = true;
        break;
    }
}
if (!$satisfies_predicate) {
    throw new APIException("No matches found");
}

// New version is much shorter and readable
if (!any($item_list, fn($item) => API::satisfiesCondition($item))) {
    throw new APIException("No matches found");
}

That example doesn't have any suitable helpers already in the standard library.
Using array_filter would unnecessarily call satisfiesCondition even after the first item was found,
and array_search doesn't take a callback.

A proposed implementation is https://github.com/php/php-src/pull/6053 - it takes similar flags and param orders to array_filter().

The implementation and RFC https://wiki.php.net/rfc/any_all_on_iterable have been updated
after finishing the previous straw poll: https://wiki.php.net/rfc/any_all_on_iterable_straw_poll_namespace

This is now a vote on PHP\iterable\any(iterable $input, ?callable $callback = null) and PHP\iterable\all(...).

A secondary vote was added for choosing between any/all and any_value/all_values within PHP\iterable.

I plan to start the vote on Monday.

Any other feedback?

Thanks,

• Tyson