Stability of Uniques

Simon Peyton-Jones simonpj at
Wed Mar 27 14:57:27 CET 2013

Yes, locally-bound uniques change all the time, to maintain scoping hygiene.  But top-level things from other modules have uniques that do not change.


From: ghc-devs-bounces at [mailto:ghc-devs-bounces at] On Behalf Of Edsko de Vries
Sent: 26 March 2013 15:05
To: ghc-devs at
Subject: Stability of Uniques

Hi all,

Consider the very simple test

  module Test2 where
  f = True

When walking the AST after renaming I see that f has unique 1912603236 and True has unique 905969694. However, when walking the typechecked AST f seems to have unique 1627390565 instead. Should I expect that the unique associated with identifiers changes between renaming and typechecking? Or is there something else that I'm missing?


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