Semigroup[Int].combine(1, 2) should be(
3
)
Semigroup[List[Int]].combine(List(1, 2, 3), List(4, 5, 6)) should be(
List(1,2,3,4,5,6
)
Semigroup[Option[Int]].combine(Option(1), Option(2)) should be(
Some(3)
)
Semigroup[Option[Int]].combine(Option(1), None) should be(
Some(1)
)
Evaluation failed : Compilation Error ; ERROR -> ')' expected but '}' found. at [292, 292, 292]
) at the end of second answer, i guess =)
Hi, I think I found two eg of code that didn't seem right.
eg 1 (factorials): in line 7 of the code, on the site (tail recursion tab) the left hand side parameter to the function call iter, was just set to n (as opposed to n-1 and the field not editable. Solving the problem with this coed therefore seemed impossible.
eg 2: In line 6 of the code, the site (higher order functions tab - last exercise on the page) didn't want to recognize the variable b. Again, solving the code like this seemed impossible.
On the other hand, hen I put my solutions into an online compiler, they gave the right results:
def factorial(n: Int): Int = {
def iter(x: Int, result: Int): Int =
if (x == 0) result
else iter(x - 1, result * x)
iter(n-1, n)
}
factorial(3)
factorial(5)
eg 2
def sum(f: Int => Int, a: Int, b: Int): Int = {
def loop(x: Int, acc: Int): Int = {
if (x >= b) acc
else loop(x + 1, acc + f(x))
}
loop(a, b )
}
sum(x => x, 1, 10)
result1andhalf, when the functions are dealing with integers - this can be misinterpreted as result + a half or result / 2 - would it make sense to bump all the numbers instead, so we'd have result 1 through 6? Or maybe result1a/result1b?
Hi!
https://www.scala-exercises.org/fp_in_scala/functional_data_structures
I'm getting compilation error while trying to submit answers for the last section on the page:
mapViaFold(t)(_ % 2 == 0) shouldBe Branch(Branch(Leaf(false), Leaf(true)), Leaf(false))Getting this:
Evaluation failed : Compilation Error ; ERROR -> missing parameter type for expanded function ((x$1) => fpinscalalib.FunctionalDataStructuresSection.treeFoldAssert(1, x$1, 0, 1, Branch(Branch(Leaf(false), Leaf(true)), Leaf(false)))) at [438, 438, 438]
I'm quite sure that "cond" is supposed to check if x is smaller then y but i got no idea how to check that with unnamed(?) values. So how do i compare them?
@EgoAkkarin you could use pattern matching for that. you might need to look at:
https://www.scala-exercises.org/std_lib/pattern_matching and
https://www.scala-exercises.org/std_lib/partial_functions
first.
Don't hesitate to ask again if you need help after doing those.
