[mercury-users] Re: Mercury Tutorial / Functions

[Goncalo Jorge Coelho e Silva]

> I *strongly* suggest you don't use DCG notation (as you have for main/2)
> until you're more familiar with how IO and uniqueness work.

 I forgot to mention on my last mail, I re-arranged the main call,
so as not to use DCGs:


:- module inter. 
:- interface. 

:- import_module io.
:- import_module string. 
:- import_module list. 
%:- import_module exception. 

:- pred main(io__state, io__state).  :- mode main(di, uo) is det. 

:- pred read_strings(list(string), io__state, io__state).
:- mode read_strings(out, di, uo) is det. 

:- pred read_strings_2(list(string), list(string), io__state, io__state). 
:- mode read_strings_2(in, out, di, uo) is det. 

:- implementation.  
:- import_module exception. 


%main --> main(IO0,IO):-
        read_strings(Ss,IO0,IO). 
  
read_strings(Ss, IO0, IO) :-
        read_strings_2([], Ss, IO0, IO). 

read_strings_2(RevSs, Ss, IO0, IO) :-
        io__read_line_as_string(Result, IO0, IO1),
        (
                Result = ok(S),
                %io__write_string(S,IO0, IO1),
                IO = IO1,
                Ss = [S | RevSs],
                read_strings_2([S | RevSs], Ss, IO1, IO) 
        ; 
                Result = eof,
                Ss = list__reverse(RevSs) 
        ; 
                Result = error(_),
                exception__throw(Result) 
        ). 

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