large files are corrupted when served through elm-reactor

[avh4]

This is a SSCCE for #213

With Elm 0.18.0, Mac OS X 10.11.6

Files larger than ~900kb are corrupted by elm-reactor when they are served.

• Create a file larger than 1MB (you can get a good one with curl -O http://norvig.com/big.txt)
• start elm-reactor from the folder with the large file
• download the file through elm-reactor (curl http://localhost:8000/big.txt > downloaded.txt)

If you now compare the downloaded file to the original, (diff -u <(xxd big.txt) <(xxd downloaded.txt)), you will see that around 900,000 characters in, the beginning of the file is repeated.

Additional info:

• The downloaded file has the same size as the original, but the content differs
• The file gets corrupted at different locations each time it is downloaded
• The beginning of the file is actually repeated several times:

  $ grep -n "The Project Gutenberg EBook of The Adventures of Sherlock Holmes" big.txt
  1:The Project Gutenberg EBook of The Adventures of Sherlock Holmes
  

  $ grep -n "The Project Gutenberg EBook of The Adventures of Sherlock Holmes" downloaded.txt
  1:The Project Gutenberg EBook of The Adventures of Sherlock Holmes
  11607:theThe Project Gutenberg EBook of The Adventures of Sherlock Holmes
  17740:Articles"The Project Gutenberg EBook of The Adventures of Sherlock Holmes
  18729:What a time it seemed! From comparing notes afterwards it was but an hour and a quarter, yet it appeared to me that the night must have almost gone, and the dawn be breaking above us. My limbs were weary and stiff, for I feared to change my position; yet my The Project Gutenberg EBook of The Adventures of Sherlock Holmes
  

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[evancz]

I wonder if this is due to using a newer version of the snap-core Haskell package. I wonder if they have any issues open along these lines, because I basically did not touch the elm-reactor code at all for this release.

[avh4]

I took a quick look and didn't see an obviously matching issues on snap-core. If I get a chance, I'll try making a bare-bones project using snap-core and see if it has the same issue so we can report it there.