[Haskell-beginners] consing an element to a list inside a file
byorgey at seas.upenn.edu
Wed Feb 10 16:00:35 EST 2010
On Wed, Feb 10, 2010 at 09:52:48PM +0100, kane96 at gmx.de wrote:
> I want to add an element to a list inside a haskell file:
> mylist = [1,2,3,4]
> in Prelude it works fine, but when I do it in a file I get the error:
> parse error (possibly incorrect indentation)
> Failed, modules loaded: none.
> in a line after this two that doesn't exist
A Haskell file is simply a list of declarations, i.e. definitions of
data types, classes, and functions. You cannot just have an
expression by itself in a Haskell file. You can write expressions at
a ghci prompt (which I assume is what you meant) because that is what
ghci is for: evaluating expressions.
Why do you want 0:mylist by itself in a Haskell file? What is its
purpose? Note that it will not modify the value of mylist (indeed,
you *cannot* modify the value of mylist once it has been defined).
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