hash.ex

# In case anyone is wondering how to easily use the :crypto hash or hmac API's from elixir-land, here you go.

File.stream!(filename, [:read, {:read_ahead, 65535}], 65535)
|> Enum.reduce(:crypto.hash_init(:sha), &:crypto.hash_update(&2, &1))
|> :crypto.hash_final
|> Base.encode16

# Line 3 opens up a stream, and we're reading in 64KB chunks from the FS which is roughly pretty efficient
# In line 4, we initialize our hash (which returns a context) and put that as the default value in the reducer
# The hash_update in the reducer returns the modified context. Remember arg1 is the item, and arg2 is the accumulator
# Line 5 we finalize
# Line 6 we turn it into hex