Template Haskell

[Simon Peyton-Jones]

Thank you for the bug report.  It certainly is a bug.  I'm fixing it now.  Sadly, I've missed the boat for GHC 6.4.2, but the fix will be in the HEAD, and in the next release.

Simon

| -----Original Message-----
| From: glasgow-haskell-bugs-bounces at haskell.org [mailto:glasgow-haskell-bugs-
| bounces at haskell.org] On Behalf Of mze at informatik.uni-kiel.de
| Sent: 15 March 2006 12:33
| To: glasgow-haskell-bugs at haskell.org
| Subject: Template Haskell
| 
| Hi,
| 
| i've got a problem with the function recover in Template Haskell:
| 
| I'd like to check, if a function is already implemented. My idea is to
| call reify with the functionname. But reify throws an error if the name is
| not in scope. So I wanted to use "recover", but it doesn't work like
| expected:
| 
|  y = $(recover (return (LitE (IntegerL 1)))
|                (reify (mkName ("ola")) >> return (LitE (IntegerL 2))))
| 
| The compilation failed: `ola' is not in scope at a reify
|                          In the definition of `y'
| I thought the value of y would be 1, if "ola" is not in scope and 2
| otherwise.
| 
| 
| And even this doesn't work (the compilation failed):
| 
|  x = $(recover (return (LitE (IntegerL 1)))
|                (report True "error" >> return (LitE (IntegerL 2))))
| 
| 
| Is there a bug in recover?
| 
| Melanie Bargstädt
| 
| 
| 
| 
| 
| 
| 
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