Hi Julian,
Thanks for the proposal! While I believe this functionality can be helpful,
I would be skeptical about adding a new module to the standard library
where only a single function has been planned. I personally wouldn't add
is_number/2, as one can simply match on the result of parse/2 instead.
However, if there is a desire to improve Integer.parse/2 and Float.parse/2
with new options, I believe those will be welcome.
Thank you!
On Sat, Jul 25, 2020 at 5:10 AM Julian Gomez <julng...@gmail.com> wrote:
> Hello Everybody,
>
> I picked up Elixir this May and It has become one of my favorite
> programming languages. I played with it back in 2014 and I regret dropping
> it.
>
> This is my proposal for a new general Number Module. Provides a clean
> abstraction.
>
> ** SEE THE ATTACHED FILES FOR EXAMPLES AND MODULE PROTOTYPE**
>
> To my knowledge, If we want to parse a string to a number we currently
> have four options:
>
> - String.to_float/1
> - String.to_integer/1
> - Float.parse/1
> - Integer.parse/1 or Integer.parse/2
>
> These are great if you already know that the string contains a valid
> number.
>
> At the moment, The Number module only contains the following functions:
>
> - parse/1 - automatic number parsing to int or float
> - parse/2 - explicit number parsing to int or float
> - parse/3 - explicit number parsing to int or float but has an extra
> step.
> - is_number/1 - does the string contain a valid number or start with a
> valid number. Compared to Kernel.is_number/1 where the value has to be in
> its proper form already
>
> parse/3 accepts three arguments:
>
> - binary - the string you want to convert to a number, implicit
> parsing.
> - data type (atom) - :integer or :float, explicit parsing.
> - options - can be a function in the Float and Integer module or pass
> in the `base` for the Integer.parse/2 function.
>
>
> My proposal is a one-liner and since it's built on top of the Integer and
> Float modules
> we can utilize their functions in conjunction with parsing the string to a
> number.
>
> Example:
>
> Parsing user input:
> { bill_amount, _ } = IO.gets("What is the bill amount? ") |> Number.parse()
>
> { tip_rate, _ ) = IO.gets("What is the tip rate? ") |> Number.parse()
>
> Number.parse( "45.565", :float, ceil: 2 ) would result in {45.57, ""}
> Number.parse( "45.565%", :float, ceil: 2 ) would result in {45.57, "%"}
>
> Valid strings return *{parsed_number, rest}* and invalid strings return
> *:error* in tradition to the Integer and Float modules.
>
> ** SEE THE ATTACHED FILES FOR MORE EXAMPLES AND MODULE PROTOTYPE**
>
> Julian Gomez
>
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