dot-notation is often omitted

[gebner]

Lean 3:

/-- Matches one out of a list of characters. -/
def one_of (cs : list char) : parser char :=
decorate_errors (do c ← cs, return c.to_string) $
sat (∈ cs)

Synport:

/-- Matches one out of a list of characters. -/
def oneOf (cs : List Charₓ) : Parser Charₓ :=
  (decorateErrors do
      let c ← cs
      return c) <|
    sat (· ∈ cs)

Note that the .to_string disappears.

[gebner]

This seems to be a bug in the AST export.