LED is my new Hello World - Mercury Time

This one was a little bit tricky and longer than I expected...it also...forced me to spend a lot of time reading the documentation as there aren't many tutorials or books about Mercury...

Anyway...in the end it's working fine, so I'm quite happy -:)

Mercury has a lot of pretty convenient functions...you just need to find them out -;)

led_numbers.m
:- module led_numbers. :- interface. :- import_module io. :- pred main(io::di, io::uo) is det. :- implementation. :- import_module list, string, int, array, char. :- pred get_leds(list.list(character)::in, list.list(character)::in, int::in, list.list(string)::out ) is det. get_leds(LDIGITS, LDIGITS_AUX, N, RESPONSE) :- ( LEDS = array([array([" _ ","| | ","|_| "]), array([" ","| ","| "]), array([" _ "," _| ","|_ "]), array(["_ ","_| ","_| "]), array([" ","|_| "," | "]), array([" _ ","|_ "," _| "]), array([" _ ","|_ ","|_| "]), array(["_ "," | "," | "]), array([" _ ","|_| ","|_| "]), array([" _ ","|_| "," _| "]) ]), list.length(LDIGITS,LEN), ( if LEN > 0 then HEAD = det_head(LDIGITS), TAIL = det_tail(LDIGITS), char.to_int(HEAD, HEAD_I:int), HEAD_N:int = HEAD_I - 48, LINE = elem(HEAD_N, LEDS), SUB_LINE = elem(N, LINE), get_leds(TAIL, LDIGITS_AUX, N, RESULT), RESPONSE = [SUB_LINE] ++ RESULT else if N < 2 then get_leds(LDIGITS_AUX, LDIGITS_AUX, N+1, RESULT), RESPONSE = ["\n"] ++ RESULT else if N = 2 then RESPONSE = ["\n"] else RESPONSE = [] ) ). main(!IO) :- io.write_string("Enter a number: ",!IO), io.read_line_as_string(Result, !IO), ( if Result = ok(String), NUM = string.strip(String), to_char_list(NUM,LDIGITS), get_leds(LDIGITS, LDIGITS, 0, RESPONSE) then io.write_string(string.join_list("", RESPONSE), !IO) else io.write_string("Not a number...",!IO) ).

Anyway...here are the screens -;)

Hope you like it -;)

Greetings,

Blag.

Development Culture.

My first post on Mercury

So...my new language for a couple of weeks...is Mercury -:)

You may ask...what is Mercury?

Mercury looks like Prolog, but feels like strict Haskell or pure OCaml.

 In other words is a logical, functional and object-oriented programming language...

As always...I needed to develop an app to learn how to use it...and while it gave me more than one headache...here it is -;)

fibo.m
:- module fibo. :- interface. :- import_module io. :- pred main(io::di, io::uo) is det. :- implementation. :- import_module string, int. :- pred fibo(int::in, int::in, int::in, string::out) is det. fibo(NUM, A, B, FIBS) :- ( if A = 0 then fibo(NUM-1,A+B,B,FIB), FIBS = int_to_string(A) ++ " " ++ int_to_string(B) ++ " " ++ int_to_string(A+B) ++ " " ++ FIB else if A > 0, NUM > 1 then fibo(NUM-1,A+B,A,FIB), FIBS = int_to_string(A+B) ++ " " ++ FIB else FIBS = "" ). main(!IO) :- io.write_string("Enter a number: ",!IO), io.read_line_as_string(Result, !IO), ( if Result = ok(String), string.to_int(string.strip(String), N) then fibo(N,0,1,FIBS), io.write_string(FIBS,!IO) else io.write_string("Not a number...",!IO) ).

The cool thing about Mercury is that it forces you to not allow your app to fail...as the "else" is mandatory...if you enter a number then it's fine...but if you enter a letter, you are forced to do something...

Here are the pics...

 Now...I just need to break my head a little bit more trying to make my LED_Numbers app -:D

Greetings,

Blag.
Development Culture.