Re: [Haskell-beginners] invalid type signature last2::: [a] -> a

You must add something like module X where at the top of your file, to indicate that this is not the main module (where you must specify a main function). Groeten, Henk-Jan van Tuyl On Sun, 09 Nov 2014 14:11:12 +0100, Roelof Wobben wrote:

Thanks,

Now when I run it, I see a error message that main is missing. and I cannot find in theIlearnyouahaskell how to solve this.

Roelof

May Khaw schreef op 9-11-2014 11:17:

The first one means that you gave a type signature for a function you did not define.

The second one means that there are 2 last2 type signature, but you can only have one.

What you want is something like : last2 :: [a] - > a last2 list = (put your function here)

On Sun, 9 Nov 2014 21:02 Roelof Wobben wrote:

Thanks,

I changed it to this :

last2::[a]-> a last2::last[a]

but now I see these error messages:

src/Main.hs@1:1-1:6 The type signature forlast2 lacks an accompanying binding

src/Main.hs@2:1-2:6 Duplicate type signatures for last2 at /home/app/isolation-runner-work/projects/75679/session.207/src/src/Main.hs:1:1-5 /home/app/isolation-runner-work/projects/75679/session.207/src/src/Main.hs:2:1-5 src/Main.hs@2:1-2:6

The type signature for last2 lacks an accompanying binding

akash g schreef op 9-11-2014 10:48:

The naming convention for variables and functions is that they should start with a lower case letter. Types have capitalized names.

On Sun, Nov 9, 2014 at 3:12 PM, Roelof Wobben wrote: Hello,

I try to solve the 99 haskell problems on several ways.

But my first try which looks like this :

Last2::[a]-> a Last2:: last[list]

gives the following error message :

src/Main.hs@1:1-1:6 Invalid type signature: Last2 :: [a] -> a Should be of form <variable> :: <type>

What am trying to do is say the input is a list which can be of integers or chars so everything is the output can then also be of type everything.

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