Text.Read.Lex.lex broken
Prelude> lex "&) = mempty"
[("&",") = mempty")]
Prelude> lex "∘) = mempty"
[]
I traced this problem to Text.Read.Lex.lex
Prelude> lex "&) = mempty"
[("&",") = mempty")]
Prelude> lex "∘) = mempty"
[]
I traced this problem to Text.Read.Lex.lex