[Compiler bug?] Infinite loop

[OlivierSohn]

When compiling on OSX with optimizations (stack clean && stack build with resolver lts-9.12 (ghc 8.0.2)), the program loops infinitely (400% CPU, and execution is blocked) when an animation is triggered.

The bug is visible at this commit : 9f25223 (to reproduce, shoot at a number in the game)

This branch reproduces the problem with a minimal amount of code:
https://github.com/OlivierSohn/hamazed/tree/repro-ghc-14521-A

stack version:

$ stack --version
Version 1.3.2, Git revision 3f675146590da4f3edf768b89355f798229da2a5 (4395 commits) x86_64 hpack-0.15.0

A ticket was opened concerning this potential ghc bug : https://ghc.haskell.org/trac/ghc/ticket/14521

[OlivierSohn]

It was not a ghc bug, it was my code that was too strict! making it more lazy fixed the issue, and compiling with -fpedantic-bottoms makes the error be deterministic.
Related commit: 5bce4fd