Quick Summary: Compilation hangs and an elm process remains active after <ctrl-c>. Memory usage of this process reaches >16GB (memory available to system) which bogged down my system.

SSCCE

module Main exposing (..)

foldMap : (a -> b) -> (a -> c) -> (b -> c -> c) -> a -> c
foldMap fab fac fbc a = fac a

break : Float -> (Float, Float)
break input = foldMap identity (\x -> (x, x)) (\( low, high ) x -> ( min low x, max high x )) input

• Elm: Elm 0.19.1
• Browser: NA
• Operating System: macOS 11.4

Additional Details

elm make hangs after printing Compiling .... The orphan elm process only continues if waiting for longer than 5-6 seconds before using to cancel the elm make command.

When changing (\( low, high ) x -> to (\x ( low, high ) -> the snippet compiles as expected, and changing ( min low x, max high x ) to ( x, x ) results in the compiler error `foldMap` needs the 4th argument to be: ( ∞, ∞ ).

Came across this writing a foldMap to calculate the min and max of a List Float but have simplified to get a minimal reproduction.

Love your work!