Re: The review of std.hash package

[Walter Bright]

On 8/8/2012 5:13 AM, Martin Nowak wrote:
It should accept an input range. But using an Output Range confuses me. A hash
function is a reduce algorithm - it accepts a sequence of input values, and
produces a single value. You should be able to write code like:
   ubyte[] data;
   ...
   auto crc = data.crc32();

For example, the hash example given is:

   foreach (buffer; file.byChunk(4096 * 1024))
       hash.put(buffer);
   auto result = hash.finish();

Instead it should be something like:

   auto result = file.byChunk(4096 * 1025).joiner.hash();

I think sha1Of/digest!SHA1 should do this.
It's also important to have a stateful hash implementation that can be updated
incrementally, e.g. from a callback.

Take a look at the reduce function in 
http://dlang.org/phobos/std_algorithm.html#reduce

It has provision for an initial state that can be the current running total.