[Haskell-cafe] Combining Network Descriptions in Reactive.Banana

Alexander Foremny alexanderforemny at googlemail.com
Wed Jun 27 16:39:39 CEST 2012

Hello list,

I am currently experimenting with Reactive.Banana and I am trying to
write a program that simply displays a String which is supplied by the
user. Thus in Main.hs I'd like to create a Behavior t String from some
arbitrary sources and pass this to a library function performing the
printing. However, I am not able to get the desired behavior of my
program. A sample Main.hs is available as Gist [1].

The cause of error appears to be that the type t over which
NetworkDescription and Behavior are parameterized are distinct! I
tried several variations of the code in [1] using
ExistentialQuantification over t and/or giving explicit type
signatures. The error is slightly different in each case, but always
boils down to the same reason.

In case explicit error messages are required I can post them to the list.

Any insight into this would be of great help. And additionally I'd be
interested if this kind of program is possible with Reactive.Banana at

[1] https://gist.github.com/3004430

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