message: Simplify concrete formatting
diff: use codespan::{ByteIndex, ByteOffset, ByteSpan};
  use std::fmt;
  -use syntax::pretty::ToDoc;
  +use syntax::pretty::{self, ToDoc};
  /// Commands entered in the REPL
  #[derive(Debug, Clone)]
  @@ -69,9 +69,7 @@ pub enum Module {
  impl fmt::Display for Module {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  - self.to_doc()
  - .group()
  - .render_fmt(f.width().unwrap_or(10000), f)
  + self.to_doc().group().render_fmt(pretty::FALLBACK_WIDTH, f)
  }
  }
  @@ -124,9 +122,7 @@ impl Declaration {
  impl fmt::Display for Declaration {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  - self.to_doc()
  - .group()
  - .render_fmt(f.width().unwrap_or(10000), f)
  + self.to_doc().group().render_fmt(pretty::FALLBACK_WIDTH, f)
  }
  }
  @@ -276,9 +272,7 @@ impl Term {
  impl fmt::Display for Term {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  - self.to_doc()
  - .group()
  - .render_fmt(f.width().unwrap_or(10000), f)
  + self.to_doc().group().render_fmt(pretty::FALLBACK_WIDTH, f)
  }
  }
  