nickel> (fun x => x.a): {} -> _
error: type error: missing row `a`
┌─ <repl-input-130>:1:11
│
1 │ (fun x => x.a): {} -> _
│ ^ this expression
│
= Expected an expression of type `{ a : _a; _rrows_b }`, which contains the field `a`
= Found an expression of type `{ }`, which does not contain the field `a`
This is rather difficult to understand. a much better message would be along these lines:
error: type error: missing field `a`
┌─ <repl-input-130>:1:11
│
1 │ (fun x => x.a): {} -> _
│ ^ this field
│
= Attempted to access field `a` on an expression of type `{ }`
@yannham