Scalar types

scalar

int, bool, float, string are examples of scalar types. Scalar types represent scalar values in PHP. These types are also valid types in PHP 7. The type scalar is the supertype of all scalar types.

int-range

Integer ranges indicate an integer within a range, specified using generic syntax: int<x, y>.
x and y must be integer numbers.
x can also be min to indicate PHP_INT_MIN, and y can be max to indicate PHP_INT_MAX.

Examples:

  • int<-1, 3>
  • int<min, 0>
  • int<1, max> (equivalent to positive-int)
  • int<0, max> (equivalent to non-negative-int)
  • int<min, -1> (equivalent to negative-int)
  • int<min, 0> (equivalent to non-positive-int)
  • int<min, max> (equivalent to int)

int-mask<1, 2, 4>

Represents the type that is the result of a bitmask combination of its parameters.
int-mask<1, 2, 4> corresponds to 0|1|2|3|4|5|6|7.

int-mask-of<MyClass::CLASS_CONSTANT_*>

Represents the type that is the result of a bitmask combination of its parameters.
This is the same concept as int-mask but this type is used with a reference to constants in code: int-mask-of<MyClass::CLASS_CONSTANT_*> will correspond to 0|1|2|3|4|5|6|7 if there are three constants called CLASS_CONSTANT_{A,B,C} with values 1, 2 and 4.

array-key

array-key is the supertype (but not a union) of int and string.

numeric

numeric is a supertype of int or float or numeric-string.

class-string, interface-string

Psalm supports a special meta-type for MyClass::class constants, class-string, which can be used everywhere string can.

For example, given a function with a string parameter $class_name, you can use the annotation @param class-string $class_name to tell Psalm make sure that the function is always called with a ::class constant in that position:

<?php
class A {}

/**
 * @param class-string $s
 */
function takesClassName(string $s) : void {}

takesClassName("A"); would trigger a TypeCoercion issue, whereas takesClassName(A::class) is fine.

You can also parameterize class-string with an object name e.g. class-string<Foo>. This tells Psalm that any matching type must either be a class string of Foo or one of its descendants.

trait-string

Psalm also supports a trait-string annotation denoting a trait that exists.

enum-string

Psalm also supports a enum-string annotation denote an enum that exists.

callable-string

callable-string denotes a string value that has passed an is_callable check.

numeric-string

numeric-string denotes a string value that has passed an is_numeric check.

literal-string

literal-string denotes a string value that is entirely composed of strings in your application.

Examples:

  • "hello " . "world"
  • "hello " . Person::DEFAULT_NAME
  • implode(', ', ["one", "two"])
  • implode(', ', [1, 2, 3])
  • "hello " . <another literal-string>

Strings that don't pass this type check:

  • file_get_contents("foo.txt")
  • $_GET["foo"]
  • "hello " . $_GET["foo"]

literal-int

literal-int denotes an int value that is entirely composed of literal integers in your application.

Examples:

  • 12
  • 12+42

Integers that don't pass this type check:

  • (int) file_get_contents("foo.txt")
  • (int) $_GET["foo"]
  • ((int)$_GET["foo"]) + 2

lowercase-string, non-empty-string, non-empty-lowercase-string

A non empty string, lowercased or both at once.

empty here is defined as all strings except the empty string ''. Another type non-falsy-string is effectively a subtype of non-empty-string, and also precludes the string value '0'.