Re: Numeric read seems too strict

Yeah, that. With a paren count and an accumulator and for fractional numbers some care around the decimal point or slash, we can look at each digit just once. Fast/lazy failure would be a pleasant side effect of running a numbers-only process from top to bottom. Yes, Read is supposed to read things that look like Haskell expressions, but it's really not a Haskell parser and pretending it is only hurts. On Oct 2, 2016 12:07 AM, "Ivan Lazar Miljenovic" wrote:

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Instead of scanning first (in lexing) to find the end of the number and

On 2 October 2016 at 14:34, David Feuer wrote: then

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scanning the string again to calculate the number, start to calculate once the first digit appears.

As in multiply the current sum by 10 before adding each new digit?

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On Oct 1, 2016 10:07 PM, "wren romano" wrote:

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On Mon, Sep 12, 2016 at 11:03 AM, David Feuer wrote:

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By the way, I believe we should be able to read numbers more

efficiently

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by parsing them directly instead of lexing first. We have to deal with parentheses, white space, and signs uniformly for all number types. Then specialized foldl'-style code *should* be able to parse integral and fractional numbers faster than any lex-first scheme.

I follow the part about parentheses and negations, but I'm not sure I get the rest of what you mean. E.g., I'm not sure how any parser could be faster than what bytestring-lexing does for Fractional and Integral types (ignoring the unoptimized hex and octal functions). What am I missing?

-- Live well, ~wren

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