[POSSIBLE BREAKING CHANGES] Create DSL for satpam rule

[sendyhalim]

I think it's better if we have our own DSL for rule e.g.

const satpam = require('satpam');

// With string (current implementation)
const rules = {
  phoneNumber: ['required', 'string'];
  title: ['required', {
    name: 'memberOf'
    params: [['mr', 'mrs']]
  }]
};

// Next implementation could be like this
const rules = {
  phoneNumber: [
    satpam.rules.required(), 
    satpam.rules.string()
  ],
  title: [
    satpam.rules.required(),
    satpam.rules.memberOf({
      acceptedValues: ['mr', 'mrs']
    })
  ]
};

Reasoning behind this is it's easier to read and it's easier to avoid rule typo, because sometimes we do something like this

const rules = {
  phoneNumber: ['require']
};

module.exports = (req, res) => {
  // Uh oh rule typo >.<, it won't happen if we have our own DSL, 
  // would throw error when starting the server
  const  validationResult = satpam.validate(rules, req.body);
  ....
};

Bonus point
we can make it backward compatible, we just need to check old rule format and if it matches then parse the rule using the old implementation

[albertstevelino]

why using function instead of attributes?
I think satpam.rules.required would be more easier

const rules = {
  phoneNumber: [
    satpam.rules.required, 
    satpam.rules.string
  ],
  title: [
    satpam.rules.required,
    satpam.rules.memberOf('mr', 'mrs')
  ]
};

[sendyhalim]

@astevelinocermati for consistency reasons and some rules have optional parameter(s)

satpam.rules.requied // undefined T_T
satpam.rules.requied() // Will be caught
satpam.rules.required({
  shouldValidate: (input, ruleObject) => input.name === 'ironman' // Will run validation if name is 'ironman'
});