Haskell parse error on input ‘|’ when trying to compile -


hi i'm learning haskell , made code implemente fractions when compile error parse error on input ‘|’ code following:

module fraccion(frac,div,mcd,fraccion)   data frac = div integer integer deriving (eq, show)   mcd :: integer -> integer -> integer mcd b | > b = mcd (a-b) b         | < b = mcd (b-a)         | == b =  fraccion :: integer -> integer -> frac  fraccion b | b == 0 = error "divisor can't 0"              | b <  0 = fraccion (-a) (-b)              | b >  0 = div (a `div` mcdab) (b `div` mcdab)                         mcdab = mcd (abs a) b  instance (num frac)     negate (div b)      = (div (-a) b)     abs    (div b)      = (div (abs a) b)     (div b) * (div c d) = fraccion (a*c) (b*d)     (div b) + (div c d) = fraccion (a*d+b*c) (b*d)     (div b) - (div c d) = fraccion (a*d-b*c) (b*d)     frominteger n = (div n 1)     signum (div b) | > 0 = 1                      | < 0 + -1                      | == b = 0  instance show frac     show (div b) = (show a) ++ "/" ++ (show b)

could please me error?

on line 27:

| < 0 + -1

a simple typo. put + meant =

| < 0 = -1

you'll want capitalize show on second-to-last line. deriving clause type shouldn't include show either, because define instance explicitly rather deriving it. finally, module export list should this.

module fraccion(frac(div),mcd,fraccion)

Comments

Post a Comment

Popular posts from this blog

python - Operations inside variables -

this question has answer here: evaluating mathematical expression in string 12 answers i want make python script finds maximum possible output using 2 operations. problem says there syntax error @ 2nd last line, in b in there. how can fix it? x = 0 = int(input("1st number:")) c = int(input("2nd number:" )) e = int(input("3rd number:" )) in range(4): if == 0: b = "+" elif == 1: b = "-" elif == 2: b = "/" else: b = "*" j in range(4): if j == 0: d = "+" elif j == 1: d = "-" elif j == 2: d = "/" else: d = "*" k = b c d e print(k) if you're after variables e on single line, couldn...
Read more

Generic Map Parameter java -

i having lot of methods of type: public static list<eduusers> getdetails(class c, map<string, integer> params) { list<eduusers> details = null; session session = hibernateutil.getsessionfactory().opensession(); transaction tx = null; try { tx = session.begintransaction(); criteria cr = session.createcriteria(c); (map.entry<string, integer> entry : params.entryset()) { cr.add(restrictions.eq(entry.getkey(), entry.getvalue())); } details = cr.list(); tx.commit(); } catch (exception asd) { log.debug(asd.getmessage()); if (tx != null) { tx.commit(); } } { session.close(); } return details; } i trying have generic method them , have written far: public static <t> list<t> getdetails(class<t> c, class<t> b) { l...
Read more

arrays - What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it? -

what arrayindexoutofboundsexception mean , how rid of it? here code sample triggers exception: string[] name = {"tom", "dick", "harry"}; for(int = 0; i<=name.length; i++) { system.out.print(name[i] +'\n'); } your first port of call should documentation explains reasonably clearly: thrown indicate array has been accessed illegal index. index either negative or greater or equal size of array. so example: int[] array = new int[5]; int boom = array[10]; // throws exception as how avoid it... um, don't that. careful array indexes. one problem people run thinking arrays 1-indexed, e.g. int[] array = new int[5]; // ... populate array here ... (int index = 1; index <= array.length; index++) { system.out.println(array[index]); } that miss out first element (index 0) , throw exception when index 5. valid indexes here 0-4 inclusive. correct, idiomatic for statement here be: for (int index = 0; index <...
Read more