[Haskell-cafe] Network.CGI and error handling

Ketil Malde ketil at malde.org
Thu May 22 08:48:05 EDT 2008


I'm trying to implement a CGI, but I have encountered some problems
with handling program errors properly. I think it boils down to this: 

The first program from the documentation at

   import Network.CGI
   cgiMain = output "Hello World!"
   main = runCGI (handleErrors cgiMain)

works fine, and ouputs a page with the expected test.  Replacing line
2 with:

   cgiMain = output $ error "Hello World!"

returns a blank page, although according to the documentation,
'handleErrors' should produce an error page (500) instead.

The error is recorded in the log, where one can read:

   [Thu May 22 14:35:27 2008] [error] [client] test.cgi: Hello World!

I've toyed with various approaches, including using catchCGI and
replacing 'error' with other run-time failures, but only getting the
same result.  Any hints?

(ghc 6.8.1, cgi-3001.1.5.1, apache 2.0, linux.)

If I haven't seen further, it is by standing in the footprints of giants

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