Strings\isBlank()

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predicate returns bool pure
mixed → bool
At a glance — A direct predicate — no curry, no Closure. True only for an empty string; whitespace, null, zero, and empty arrays all return false.

Checks whether a value is a string of zero length. Returns true only if the value is a string and its multibyte length is 0; any non-string value (null, int, array, etc.) returns false. 

/**
  * @param mixed $value
  * @return bool
  */
Strings\isBlank($value): bool

Examples

Partial Application

This can be used to create a simple closure which can be used as a regular function. 

// isBlank is called directly with the value under test — it is not a partially applied constructor like the rest of the Strings namespace.
var_dump(Strings\isBlank(''));     // true
var_dump(Strings\isBlank('foo'));  // false

// Only a zero-length string is considered blank. Any non-string value returns false.
var_dump(Strings\isBlank(null));   // false
var_dump(Strings\isBlank(0));      // false
var_dump(Strings\isBlank([]));     // false

// A string of whitespace is NOT blank — trim the input first if you need that behaviour.
var_dump(Strings\isBlank(' '));                 // false
var_dump(Strings\isBlank(Strings\trim(' ')(' '))); // true

Inlined with Higher Order Function

If you are not planning on reusing the Closure created, you can just call it inline with a higher order function as its callable. 

// Pass the fully qualified name as a string callable to any higher order function.
$values = ['', 'foo', '', 'bar', ''];

$blanks = array_filter($values, 'PinkCrab\FunctionConstructors\Strings\isBlank');
print_r($blanks); // ['', '', '']

// Or use it as a negated predicate to strip blanks out.
$nonBlanks = array_filter($values, fn($v) => ! Strings\isBlank($v));
print_r($nonBlanks); // ['foo', 'bar']

Details

Strings Functions

Releated String predicate Functions