On 3/13/15 8:37 AM, Chris wrote:
Yep. This is part of the "make people feel good about it" approach.
Plus, we're not selling shit, it's really a good product. In a way, we
do it the other way around: bad marketing for a good product.
Yah, indeed. Continuing the experiment, I set out to find Go's
startsWith. So I googled for ``startswith golang''. First hit is
http://golang.org/pkg/strings/ but there's no StartsWith on that page.
The second hit is
http://stackoverflow.com/questions/13244048/no-startswith-endswith-functions-in-go,
which puts me in the right direction - HasPrefix is the name. So I click
on that and I get to http://golang.org/pkg/strings/#HasPrefix.
That has no example but the signature is obvious enough. Just to verify,
I click on the "Example" link on the function "Index" below, and I edit
these lines:
fmt.Println(strings.Index("chicken", "ken"))
fmt.Println(strings.Index("chicken", "dmr"))
to:
fmt.Println(strings.HasPrefix("chicken", "chi"))
fmt.Println(strings.HasPrefix("chicken", "dmr"))
Click Run produces "true\nfalse" and... I got it.
* * *
Now here's the interesting part. There's a world of difference between
D's startsWith and Go's HasPrefix. (Not because there's anything wrong
about HasPrefix.) It's just that startsWith is very powerful -
disconcertingly so. It is quite literally the ultimate startsWith:
* Works with any combination of UTF8, UTF16, and UTF32.
* Works with not only strings, but any arrays
* Works with array and element (e.g. "abc".startsWith('a')), not only
array and array
* Equality is too much? You can pass a predicate
* Efficiently looks for multiple prefixes in a single pass, e.g.
"abc".startsWith("ab", '#')
* Scratch "array", works with any two ranges with comparable elements
and for any range and comparable element
For example the expression (assuming s is e.g. a string)
File("/tmp/a").byChunk(4096).joiner.startsWith(s)
opens a file, progressively reads chunks of 4KB, stitches them together
at no cost, compares against a prefix until it makes a decision, then
closes the file and returns the result. A putative Go user wouldn't even
dream of using HasPrefix directly on a stream coming from a file; the
whole endeavor would be a function that painstakingly takes all of these
steps by hand.
We need to take the "disconcerting" out the documentation equation while
still exposing the power. s1.startsWith(s2) is perfectly apt for two
strings, and that should be immediately apparent to someone who just
needs that.
Andrei
