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pisethkem | 27 Nov 09:52
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Re: beginner question about typing

--- In ocaml_beginners <at> yahoogroups.com, "ben.aurel" <ben.aurel <at> ...> wrote:
>
> hi
> I make another attempt with ocaml and it seems like it doesn't fit my
> brain yet.
>
> ---
> let max a b =
> if a > b then a else b
> ;;
>
> print_newline (max 3 5) ;;
>
> ---
>
> The error message is the following:
> This expression has type int but is here used with type unit
>
>
> If tried several things like 'int max' or casting like 'then int a',
> but it doesn't work.
>
> What am I doing wrong here?
> thanks
> ben
>

you miss the case when a = b

let max a b =
if a <= b then b else a;;

print_int (max 3 5);;

piseth kem

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Till Crueger | 27 Nov 10:22

Re: Re: beginner question about typing

On Thu, 27 Nov 2008 09:52:18 +0100, pisethkem <pisethkem <at> yahoo.com> wrote:

>> let max a b =
>>     if a > b then a else b
>> ;;
>>
>> print_newline (max 3 5) ;;
[snip]
> you miss the case when a = b
>
> let max a b =
> if a <= b then b else a;;
>
> print_int (max 3 5);;

Please don't confuse beginners.... There is no "case missing" in the above  
example. The only Problem was with the print_newline instead of the  
print_int...

The max functions you gave and he gave are completyl identical as can be  
proven by some simple transformations, like
!(a > b) <=> a <= b
and
if !x then a else b <=> if x then b else a

Apart from that the case a = b is even more irrelevant because in that  
case it does not matter if you return a or b...

Greetings,
   Till

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