Add a simple customPartial implementation

[Demivan]

Related #76

This is an extremely simplified implementation of the proposed “partial pipe” solution.

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[fabian-hiller]

Thank you for the draft!

[fabian-hiller]

Do you have any alternative name ideas for customPartial. Will it only work or make sense in the pipe of object?

[fabian-hiller]

Beside PR #211, I would like to focus on a solution to this problem in the next week. It will also be important to be able to specify the path where the error message should be applied.

[Demivan]

Do you have any alternative name ideas for customPartial. Will it only work or make sense in the pipe of object?

Maybe something like whenValidated or whenFieldsValid.
It only makes sense with object pipe. So would be nice to have type system prevent usage with other validations.

[fabian-hiller]

I have added a partialCheck action and think that we can close this PR. Here is a code example:

import * as v from 'valibot';

const RegisterSchema = v.pipe(
  v.object({
    email: v.pipe(
      v.string(),
      v.nonEmpty('Please enter your email.'),
      v.email('The email address is badly formatted.'),
    ),
    password1: v.pipe(
      v.string(),
      v.nonEmpty('Please enter your password.'),
      v.minLength(8, 'Your password must have 8 characters or more.'),
    ),
    password2: v.string(),
  }),
  v.forward(
    v.partialCheck(
      [['password1'], ['password2']],
      (input) => input.password1 === input.password2,
      'The two passwords do not match.',
    ),
    ['password2'],
  ),
);