Create custom scalar sub types to make $id's more specific.

[joelharkes]

I'm working in a codebase right now that heavenly relies on passing $modelId's to the services.
It uses psalm to doctype which is already great! But since everything is the same scalar type it doesn't really stop you from making these mistakes:

function check(int $userId, int $roleId){...}

check($roleId, $userId);

It would be nice if you can make custom types that are somehow stricter.
Like this below is allowed, but would be nice it it actually throws an error that $x is not a RoleId

<?php

/**
 * @psalm-type UserId = int
 * @psalm-type RoleId = int
 * @param UserId $userId
 * @param RoleId $roleId
 */
function takesAnInt(int $userId, int $roleId): bool {
    
   return $userId > $roleId;
}

/** @var UserId $x */
$x = 2;
takesAnInt($x, $x);

I did some digging around but found no resources for this?

[joelharkes]

see: https://psalm.dev/r/28737f8105

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/28737f8105

<?php

/**
 * @psalm-type UserId = int
 * @psalm-type RoleId = int
 * @param UserId $userId
 * @param RoleId $roleId
 */
function takesAnInt(int $userId, int $roleId): bool {
    
   return $userId > $roleId;
}

/** @var UserId $x */
$x = 2;
takesAnInt($x, $x);

Psalm output (using commit 765dcbf):

No issues!