I've made this elixir module that should print each number, "counting" up to the number you give it.
defmodule Count do
def to(n) do
m = 1
_to(n, m)
end
defp _to(n, m) when (m <= n) do
IO.puts "#{m}"
x = m + 1
_to(n, x)
end
end
...but when I run it, it performs exactly as expected except that it throws this error at the end. What is happening here?
iex(1)> Count.to 5
1
2
3
4
5
** (FunctionClauseError) no function clause matching in Count._to/2
count.exs:6: Count._to(5, 6)
iex(1)>
Thank you for any help.
Elixir doesn't silently ignore a function call if none of the clauses match -- you get a FunctionClauseError
. In this case, when m > n
, no function clause in _to
matches, so Elixir throws that error. You need to add another version of _to
which accepts any m
and n
(or you could add a when m > n
there, if you want) and does nothing.
defp _to(n, m) when (m <= n) do
IO.puts "#{m}"
x = m + 1
_to(n, x)
end
defp _to(n, m) do
end
You did not handle the case when m > n
, but you are still calling it. You either dont call it, or have a function definition that handles this case.
defp _to(n, m) when (m <= n) do
IO.puts "#{m}"
x = m + 1
_to(n, x)
end
defp _to(n, m), do: IO.puts "Completed Counting" end
This shortens it up after looking at the answers given here. The explanation for the answer was a great one, thank you guys.
defmodule Count do
def to(n, m \\ 1)
def to(n, m) when n == m, do: IO.puts "#{n}"
def to(n, m) do
IO.puts "#{m}"
to(n, m + 1)
end
end
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