Re: Clojure's handling of numbers with a trailing decimal point

[Stephen C. Gilardi]

Clojure's number syntax is documented at http://clojure.org/reader to be:

May I please enter an issue to track it and provide a patch?

--Steve

On Apr 24, 2009, at 6:07 PM, Stephen C. Gilardi wrote:

Numbers - as per Java, plus indefinitely long integers are supported, as well as ratios, e.g. 22/7. Floating point numbers with an M suffix are read as BigDecimals. The enclosed posting reports an unnecessary divergence from "as per Java" that I'd like to fix.

I noticed today that a series of digits with a trailing decimal point are read by Clojure as an Integer.

        user=> (class 123.)
        java.lang.Integer

In contrast, Java reads such a number as a double.

        % javac Foo.java
        Foo.java:5: possible loss of precision
        found   : double
        required: int
                    int a = 123.;
                            ^
        1 error



        user=> (class 123.e4)
        java.lang.NumberFormatException: Invalid number: 123.e4
        java.lang.Exception: Unmatched delimiter: )
        user=>

Java reads it as 1230000.0



--Steve

Another place this comes up is with a number formatted as 123.e4. Currently that's an invalid number in Clojure: To bring Clojure in line with Java for numbers formatted this way, I propose changing the reader to match Java's behavior for these cases. I have a patch which I'll attach to an issue if one is approved.

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