Purity | CLR-Hosted Total Functional Programming Language

No idea what your dataset is like or where exactly is the error in your code. Too many redundant parts.

If the purpose is to use average precision score as stated, then you can use make_scorer, assuming your labels are binary, 0/1 like in example below:

I can't help but thinking that when the exception does occur from within bracket's 3rd argument, bracket is not returning an IO c.

I think there is a clever solution within your problem. Create a method on your VendorBill.php model, that concats the codes.

Make your values std variants over the 3 types.

Failing that, boost variant.

Std and boost variant really are what you want. You'll end up implementing some subset of its implementation.

Failing that, find a tutorial on how to implement ones of them, or use std any. Failing that, dynamic casts around an otherwise useless wrapper type with a virtual dtor stored in a unique ptr, or do manual RTTI with try get methods.

This just gets increasingly ugly and/or inefficient however.

Boost variant, and std variant from it, was implemented for a reason, and that reason was solving the exact problem you are describing in an efficient manner.

When taking the Wikipedia definition to the letter, a function that takes as argument a reference to a mutable data structure (such as a native Array) is not pure:

Its return value is the same for the same arguments (no variation with local static variables, non-local variables, mutable reference arguments or input streams from I/O devices).

Although this clearly says "no variation with mutable reference arguments", we could maybe say this is open to interpretation and depends on the meaning of "same" and "variation". There are different definitions possible, and so we enter the area of opinion. Quoted from the paper your referred to:

There is not a single obviously right answer to these questions. Determinism is thus a parameterized property: given a definition of what it means for arguments to be equivalent, a method is deterministic if all calls with equivalent arguments return results that are indistinguishable from within the language

The functional purity proposed in the same paper, uses the following definition of equivalence:

Two sets of object references are considered equivalent if they result in identical object graphs

So with that definition, the following two arrays are considered equivalent:

You seem to want:

Here's a solution using a package called yahooquery. Disclaimer: I am the author of the package.

Use a conditional window functions:

If spellname is not in spell.spelldictionary, i becomes spell.spelldictionary.length after the for loop, and the execution of msg.channel.send(spell.spelldictionary[i][1]) causes the error.

You can avoid it by moving msg.channel.send before break in the for loop, so that no message will be sent in this case. Also, it is better to explicitly declare i before using it, or it may cause some unexpected bugs after your code becomes more complicate.