"Found hole"

Brandon Allbery allbery.b at gmail.com
Tue Jan 20 18:44:01 UTC 2015

On Tue, Jan 20, 2015 at 1:36 PM, Volker Wysk <verteiler at volker-wysk.de>

> What is a "hole"?


When I replace "_exit" with "foo", it produces a "not in scope" error, as
> expected. What is special about "_exit"? It doesn't occur in the Haskell
> Hierarchical Libraries.

The leading underscore invokes the typed holes extension. If you want to
use such names, you'll need {-# LANGUAGE NoTypedHoles #-} as the first line
of the source file. (I am not sure why this extension was enabled by

brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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