Subscript numerals in type error reporting
The Futhark compiler reports type errors like so:
Cannot unify `t₅`' with type t₄ as `t₅` must be one of i8, i16, i32, i64, u8, u16, u32, u64, f32, f64 due to integer literal at > :1:19-19). When matching type t₄ with t₅
GHC reports type unification using things like
b1. I propose that it instead report not being able to match
b₁, for example.