[Haskell-cafe] Functions are first class values in C

[Cristian Baboi]

On Sat, 22 Dec 2007 17:25:34 +0200, Philippa Cowderoy <flippa at flippac.org>  
wrote:

> On Sat, 22 Dec 2007, Cristian Baboi wrote:
>
>> On Sat, 22 Dec 2007 17:13:55 +0200, Philippa Cowderoy  
>> <flippa at flippac.org>
>> wrote:
>>
>> > Here's a trivial example that does so:
>> >
>> > (\x -> x) (\x -> x)
>> >
>> > A lambda calculus classic that doesn't typecheck in Haskell:
>> >
>> > (\x -> x x) (\x -> x x)
>>
>> > Feel free to try evaluating it!
>>
>> Thank you for your message.
>>
>> I tryed and this is what I've got:
>> ERROR - cannot find "show" function for:
>> *** Expression : (\x -> x) (\x -> x)
>> *** Of type    : a -> a


> Yep, that's because while it can evaluate it down to (\x -> x) your
> interpreter doesn't know how to print the result. You can demonstrate  
> that
> it works by then passing in something to that result though:
>
> ((\x ->x) (\x -> x)) 1

I know that.  The reason the interpreter doesn't know how to print the  
result is because converting functions to strings doesn't make sense.

Thank you.

> You'll have to evaluate the other one by hand. Don't spend too long with
> it though!

Don't worry, I'm lazy too :-)