TUPLE UNPACKING CODE
carping when Peter Norvig's code won't pass PEP 8. That concepts and implementation have some overlap but should occupy a different concept maps in our brains - very much like the idea that dicts can do set-like things but that we're better off thinking about dicts as doing lookups and sets as doing uniquification, membership-testing, and set-to-set operations. Sorry for the small rant, but I think this pedantic point isn't a useful line of thinking. Raise RuntimeError('unexpected kind of item') # Something that would work but they we don't do They mostly live in different worlds because we use them and think about them much differently:
We would almost never substitute the latter for the former. However, arguing that one is a special case of the other misses the entire point of structural pattern matching. The former raises an error for a non-iterable and the latter just skips the case for a non-sequence. The former works for any iterable and the latter requires a sequence. Is similar to a match/case with a sequence pattern:
Som uninterestingly, it is possible to do only one of those things: IOW, the match/case tool can pattern match and destructure at the same time. Languages such as Python and Clojure show that there is inherent value in the destructuring assignment/bind, even out of the context of control flow. This gives the impression that the important part is the control flow. Most often, when I have seen pattern matching described to an audience with a background in imperative languages, it is compared to a super-powered switch statement. It is my understanding that there are several libraries available that implement pattern matching, but I do not use these. There is no tightly-linked control flow structure that goes along with this binding mechanism. Clojure functions and `let` bindings can use a destructuring syntax to bind to elements in a data structure. There is no control flow tied to this operation, except for the exceptions that can be thrown when the LHS and RHS have incompatible structure.Ĭlojure is another example of a language with destructuring binding that is not tied to a control flow construct. This article describing the Python feature of multiple assignment demonstrates only the destructuring assignment (assignment, because it is Python and these variables can be reassigned). And this is how we achieve tuple unpacking."Pattern matching", in the context of functional programming languages, most often refers to the complex combination of destructuring bind and conditional control flow based on which binding succeeded.
Here we have defined a tuple variable t2 and passed tuple items to it and then we have applied the concept of unpacking to it, that is the first item goes to a variable second item goes to the b, and so on. This is completely the opposite of tuple packing in this we assign each element of a tuple into different variables explicitly. And in this way, we achieve tuple packing. We have taken 4 variables a, b, c and d and in those variables, we have passed data, and all those 4 variables we passed to t4. In tuple packing, we assign tuple items to a single variable or we assign multiple items to multiple variables and at the end, we assign all those multiple items to a single variable. We saw everything in detail about tuple in the previous article, now let us see what is packing? We can only apply two methods to tuple aa it is immutable. A tuple is one of 4 built-in collection data types and the other three are list, set, dictionary.
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