Hello,

> Hence the need to perform a "run" operation like runIdentity,
> evalState or runParser (for Parsec) to get something useful to
> happen.  Except for lists we don't seem to do this.  I suppose lists
> are so simple that the operators :, ++ and the [] constructor do all
> we ever need with them.  Finally there is no runIO because "main" is
> essentially that function in every real program? - Greg
>
For lists, head is probably the simplest "run" operation.

As Brian noted earlier unsafePerformIO is a way to "run" IO computations within your code; but doing so breaks the abstraction of IO as being the outside world.

-Jeff



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