nh2's Haskell TODOs

A collection of concrete, not-too-large open-source work items to improve Haskell.

I would appreciate somebody working on them, or funding me to get them done.

Small

• Fix all syscalls in unix that don't check for EINTR
  • haskell/unix#86
  • haskell/unix#88
• Fix blocking filesystem operatons in unix:
  • https://ghc.haskell.org/trac/ghc/ticket/13296
  • For example, stat() is blocking on Linux, so the only way to make it not block the entire Haskell RTS is to make it a safe syscall instead of an unsafe one
  • c_stat called here https://github.com/haskell/unix/blob/312ed2165d04b4c8db7b07133209f69b19b45745/System/Posix/Files.hsc#L174
  • c_stat defined as unsafe here in GHC: https://github.com/ghc/ghc/blob/945c45ad50ed31e3acb96fdaafb21640c4669f12/libraries/base/System/Posix/Internals.hs#L468-L469
  • The GHC patch that would make this equally fast seems ready, just needs docs: https://phabricator.haskell.org/D1466
• Implement O_CLOEXEC
  • https://mail.haskell.org/pipermail/libraries/2017-June/028073.html
  • Full support from many people, including John Lato and ekmett
• Implement http://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=24412edeaf556a for removeDirectoryRecursive
• Implement overflow aborts as a GHC option (see https://danluu.com/integer-overflow/ for the cost), then fix all packages
• Figure out inlining problem in one client project ("p-interface") I worked on (GHC pessimising code)
• Implement system call tracing library in Haskell
  • I did this: hatrace
• Implement atomic and durable file writes for Haskell
  • We did this with FP Complete (blog post)
  • Further improvements using O_TMPFILE are upcoming
• Extract Paypal v2 API I wrote into own package

Large

• numpy clone with ABI compatibility to numpy, untyped and replicating the entire numpy API
  • numpy is already working to separate the core C libs from the PyObject stuff: https://docs.scipy.org/doc/numpy-1.12.0/reference/c-api.coremath.html
  • LumiGuide would be interested in this
• Finish the SIMD support in GHC and vector
  • https://www.reddit.com/r/haskell/comments/6jlln8/when_competing_with_c_fudge_the_benchmark_xpost/djffyrt/
  • Support by GHC HQ, ekmett

Things you should probably contract me for

Because I already have almost-working prototypes for this:

• Making GHC deterministic, producing bit-identical output
• Solving the [TH] recompilation problem
  • TODO: Publish my writeup of what the problem is

Bounties

Putting my money where my mouth is, I'll personally pay 500 EUR for any of these to be implemented (coordinate with me first!):

• Remove all nub, (\\), delete and so on functions from GHC and measure the performance on large projects and in nix (where lots of flags are passed)
• Make all file operations safe so they don't block (https://ghc.haskell.org/trac/ghc/ticket/13296)
• TH recompilation check for ghci (https://ghc.haskell.org/trac/ghc/ticket/4900)