Regression regarding Unicode subscript characters in identifiers
As reported by both hvr as user Yongqian Li:
The [changeset:d4fd1680 Unicode 7.0 update] in GHC 7.10 had the side effect of breaking code making use of subscript symbols that did compile with GHC 7.8.4, but won't anymore with GHC 7.10.1:
For instance, GHCi 7.8.4 accepts
let xᵦ = 1 let xᵤ = 1 let xᵩ = 1 let xᵢ = 1 let xᵪ = 1 let xᵣ = 1 let xₙ = 1
whereas GHC 7.10.1RC fails parsing those with a lexical error. (NB: GHC 7.8 does not accept all latin subscript letters either).