Add fixed-point precision (or format) validation to zen/number

[qdzo]

It is suitable to have constraints on decimal numbers like:

• precision (number of digits in the value)
• scale (number of digits after comma)

Sources: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toPrecision https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed

Or maybe add format like in "##.#"

https://docs.oracle.com/javase/7/docs/api/java/text/DecimalFormat.html

[carbon-hvze]

https://github.com/zen-lang/zen/blob/master/pkg/zen/tests/types-test.edn#L441

[carbon-hvze]

@qdzo when you have a chance to test the implementation please get back to me so I can close the issue

[qdzo]

Hi, @carbon-hvze . Thanks for fast feedback.

Checked implementation and found interesting issue with leading zeroes and trealing zeroes after dot.

Clojure's reader drop trailing zeroes, and leave only one before dot

10.000 -> 10.0

and also drops leading zeros.

0001 -> 1

and if we set :scale 2 or :precision 4 and pass value 10.00 validation will fail in both scenarios. and with :precision 2 - if we pass 01 we also will get validation fail.

Maybe we need edge case here.

Everything else works great

[carbon-hvze]

after the discussion we agreed upon the following:

1. for trailing zeroes use case - implement a rule that allows arbitrary number of zeroes after the dot (e.g. 10.0 will pass for scales 1,2,3, etc)
2. for opening zeroes use case do not do anything as of right now

[carbon-hvze]

@qdzo hey please take a look at the trailing zeroes logic, if it suits your needs I will go ahead and close the issue

[qdzo]

Tested. Everything as expected. Thanks.

[carbon-hvze]

nice! closing the issue then

[qdzo]

We had to allow missing trailing zeroes after decimal point - because JSON remove all trailing zeroes and convert float to integer.

Example: 1.0 -> 1

And we don't have any way to prevent that behaviour.

[qdzo]

1ee4d37afdb625db4d28202043f2d608631b91ec also related to this problem.

Fixed validation of integer value when have scale = 1