Should TH TExp be able use the Q monad

Simon Peyton Jones simonpj at
Mon Apr 18 13:45:00 UTC 2016

Well, it opens up the entire issue of dependence on typechecking order and reification.  Other things being equal, simple is good...


|  -----Original Message-----
|  From: Richard Eisenberg [mailto:eir at]
|  Sent: 18 April 2016 14:36
|  To: Simon Peyton Jones <simonpj at>
|  Cc: Boespflug, Mathieu <m at>; mainland at; Manuel M T
|  Chakravarty <chak at>; ghc-devs <ghc-devs at>
|  Subject: Re: Should TH TExp be able use the Q monad
|  On Apr 18, 2016, at 9:14 AM, Simon Peyton Jones <simonpj at>
|  wrote:
|  >
|  > My instinct is to make it less expressive, though, and only allow
|  (TExp t) as the argument of $$.
|  >
|  > Does anyone care either way?   I suppose we'd better open a ticket
|  for this.
|  I don't see any harm that is introduced by having access to the Q
|  monad. As you say, as long as we can create only well-typed TExps, it
|  doesn't seem to matter what information we have access to on the way.
|  In other words: what's the gain by reducing expressiveness here?
|  Richard

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