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Comment by 3JPLW | Hacker News Reader

Also note that the author asks for the native code for arguments of type `(AbstractString, Float64)`. The first is an abstract type — which means that this code will never get called in the first place. Julia will resolve the type of the string, and then dispatch to the concrete implementation. Which, for an ASCIIString, is 3x shorter.

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This is actually a good point, but what about Unicode? Will `(UTF8String, Float64)` emit another function?

It's the same on 0.4, and Strings are getting a big overhaul on 0.5. Here are the results for 0.4:

    $ julia -e 'f(a, b) = @sprintf("this is a %s %15.1f", a, b); code_native(f, (AbstractString, Float64))' | wc -l
    WARNING: Returned code may not match what actually runs.
         628

    $ julia -e 'f(a, b) = @sprintf("this is a %s %15.1f", a, b); code_native(f, (ASCIIString, Float64))' | wc -l
         194

    $ julia -e 'f(a, b) = @sprintf("this is a %s %15.1f", a, b); code_native(f, (UTF8String, Float64))' | wc -l
         194

Thanks, this looks better. I'll need to update the post.

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