[web-devel] Yesod change: mutable session

Michael Snoyman michael at snoyman.com
Tue Oct 26 08:42:28 CEST 2010

Hey all,

One of the things which has been a stumbling block of Yesod users has
been the semantics of setSession. In particular, it seems strange that
this does not work:

myHandler = do
    setSession "foo" "bar"
    Just "bar" <- getSession "foo"

Up until now, I have kept the "input" session that the user submitted
in his/her request separate from the "output" session which will be
sent in the response. I've just pushed a change to the repo which
modifies things so the above code works. I don't *think* this will
break anyone's code, unless you were relying on the old behavior in a
strange way I can't think of. If this causes anyone problems, please
let me know soon; Yesod 0.6 should be released either today or


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