Re: Underscore in binary literals

Hi, I for one, would like to have this in more than just BinaryLiterals (which I find rather useful as well!) I’d like to see `_` in any numeric literal being simply ignored, as I find it makes writing and reading numbers in source code much easier. let i = 1_000_000 :: Int f = 1_123.456 :: Float b = 0b1100_0011 And grouping (via underscore) might be very much domain specific. (One might want to denote magnitudes or patterns.) I ended up writing a quite a bit of stupid boilerplate[1] to support readable binary notation[2]. Cheers, Moritz — [1]: https://github.com/angerman/data-bitcode/blob/c9818debd3dae774967c0507882b6b... [2]: https://github.com/angerman/data-bitcode/blob/c9818debd3dae774967c0507882b6b...

On Sep 26, 2017, at 9:19 PM, Takenobu Tani wrote:

Hi Rahul,

Thanks for the explanation. Hmm, Is not there much need...

Thank you code example. I will also look at lexer for my study [1].

[1]: https://phabricator.haskell.org/D22

Thank you :) , Takenobu

2017-09-26 21:58 GMT+09:00 Rahul Muttineni : Implementation-wise, it's no so difficult to include - the lexer needs to be tweaked. But it seems like a specialised use-case that will only affect a minority of users is probably not worthwhile as an extension to the language/compiler.

Maybe you can try using OverloadedStrings and implement this as a library?

``` newtype Binary = Binary Integer deriving Num

instance IsString Binary where fromString binaryLiteral = error "Code here to parse binary literal with underscores"

binaryVal :: Binary binaryVal = "1101_1110_0101" ```

Hope that helps, Rahul

On Tue, Sep 26, 2017 at 8:40 AM, Takenobu Tani wrote: Dear devs,

GHC's BinaryLiterals extension is useful. (For example, x = 0b110111000101)

Is it difficult to include underscore(_) in the format like Verilog-HDL[1] ? (For example, x = 0b1101_1100_0101)

[1]: https://inst.eecs.berkeley.edu/~cs150/fa06/Labs/verilog-ieee.pdf#page=20

Regards, Takenobu

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