A series of implementations of the simplest form of yes, outputting an endless loop of y\n.

Inspired by, and C solutions based on, this Reddit post.

hsbyte based on this Reddit comment.

To compile, simply run :

make

To run a specific test, run :

./speedtest.sh [test]

To see the list of compiled tests, just run :

./speedtest.sh

To test GNU yes, or the yes installed on your system, run :

yes | pv > /dev/null

These results are completely not rigorous. Each test was only run once for a total of 5 seconds each, which I believe was sufficient enough to see the improvements in each.

The percentages for each speed is of the speed of the intial test of GNU yes.

yes

5.53 GiB/s

sh.sh (echo "y")

593 KiB/s (0.01%)—There is a lot of overhead from each call to echo.

shunroll.sh (echo "y\ny\ny\n...")

40.1 MiB/s (0.71%)—Less overhead due to less calls to echo, since each call prints multiple lines of y\n.

hs

12.3 MiB/s (0.21%)

hslist (infinite list)

9.07 MiB/s (0.16%)—Overhead of list usage.

hsbuf (manual flush every 8192)

196 MiB/s (3.46%)—Vast improvements from manually flushing and disabling flushing upon every newline.

hsbyte (use ByteString.Char 8)

4.08 GiB/s (73.78%)—Extreme improvements from using ByteString instead (based on this Reddit comment).

c (printf)

138 MiB/s (2.44%)

cputs (puts)

203 MiB/s (3.58%)—Savings from not doing unnecessary formatting.

cbuf (write with buffer size 8192)

5.51 GiB/s (99.64%)—Extreme improvements from taking a leaf out of GNU yes's book—we write directly using buffer size of 8192.

• bash
• ghc
• gcc
• make
• pv
• yes (maybe)