I have a function with a condition: def iteraterefs(divisor, number, table, out, i) when number >= divisor do number = number - divisor out = out <> elem(table, i) end However it seems that the compiler does not like the condition when number >= divisor do, is there something about reu…

IMO this thread is getting a bit too micro, you are kind of posting an error after error and I think you should step back and just post your entire module source code, and state the end goal. It also sounds like you haven’t practiced Elixir enough if lack of mutability and the lexical scope are sti…

Hi @tbk the code you show looks valid to me. Can you show the actual error you get?

I am using the Exercism practice platform which attempts to test the code ** (FunctionClauseError) no function clause matching in RomanNumerals.iteraterefs/5 ... Attempted function clauses (showing 1 out of 1): def iteraterefs(divisor, number, table, out, i) when number >= divisor In th…

FunctionClauseError is what I’d expect from iteraterefs if it was called with number < divisor. You likely need to define it for those inputs as well to pass Exercism’s tests. [image] tbk: Enum.each(refs, fn(divisor) -> iteraterefs(divisor, number, table, out, i) i = i + 1 …

Pinning variables only performs a match, it doesn’t create a binding. You aren’t actually doing any pinning in your example so I’m not quite sure how you are picturing it would work but, for example, this doesn’t work: foo = 1 ^foo = 1 + 1 # This is a match error ^foo = 1 + 1 gets expanded to 1 =…

I was imagining something like foo = ^foo + 1 which would reference the variable in the outer scope. Or is foo destroyed when it leave scope?

[image] tbk: Or is foo destroyed when it leave scope? Yes, it is. It’s a bit confusing terminology-wise since we do say we can re-bind variables but really it might be easier to think of as you are only reusing the names. It doesn’t affect any outer scopes. [image] tbk: foo = ^foo + 1 …

It was my reading of those examples from the docs to interpret the ^ as something like a “type/value checked deference”. Forging ahead, ignoring what I was told about the scope of out, I’ve restructured my code in a recursive manner. def iteraterefs(number, refs, table, out, i) when number > 0 d…

Sorry, my example may have been a bit confusing. The out = out <> symbol isn’t doing anything other than assigning out <> symbol to out then throwing it away. You can rebind variable from outer scope. foo = "bar" if true do foo = "bazzzz" end foo # This is still "bar" You can reference an oute…

This I understand from your explanation I was just attempting to address getting the function iteraterefs to compile with inputs. I’ll worry about variable assignment after that.

Elixir Programming Language Forum

Reusing function variables in a `when` conditional

Questions & Help Questions

tbk February 8, 2024, 6:35pm 5

Isn’t the solution to variable scope to pin the variables?