My first ChatGPT exchange

[2022-12-11 Sun] on Yann Esposito's blog
My first interaction with ChatGPT about Clojure and Monads.

The first few questions for ChatGPT

I finally opened an account to beta-test ChatGPT. I must say, I am quite impressed. I asked it a few questions that I could have asked during an interview. To my surprise, the answer given was, while wrong, believable enough to kind of sneak the answer as right up to some imprecision. Like if you squint enough, it could pass, but if you pay attention it is clearly false.

So yes, mainly ChatGPT in this interaction was quite good at being convincing. This is the same kind of impression you have from looking at AI generated images. At first sight everything seems fine, but if you start looking to the details, many things are off.

So here is the full interaction, I'll let the attentive reader find the technical problems:

me Can you write a clojure function that will reverse any string provided to it.

ChatGPT: Sure, here's a possible implementation of a function that reverses a string in Clojure:

(defn reverse-string [s]
  (apply str (reverse (seq s))))

This function takes a strings as input, converts it to a sequence of characters using the seq function, reverses this sequence using the reverse function, and then converts the resulting sequence back to a string using the apply and str functions.

Here's an example of how you can use this function:

user=> (reverse-string "hello world")
"dirow olleh"

Note that this function only works for strings that contain characters in the Unicode Basic Multilingual Plane (BMP), since the seq function only works on strings that contain characters in this range. If you need to reverse strings that contain characters outside of the BMP, you can use the string-seq function instead of seq to convert the string to a sequence of characters.

me How would this function react if instead of string you provide an integer?

ChatGPT: If you provide an integer as input to the reverse-string function instead of a string, the function will fail with a ClassCastException because the seq function only works on strings, and you cannot convert an integer to a string in a straightforward way in Clojure. The seq function expects its input to be a string or a collection, such as a vector or a list, and when you try to pass an integer to it, it will try to convert the integer to a string by calling the str function on it. However, since str only works on strings and collections, and not on numbers, this will result in a ClassCastException.

Here's an example of what will happen if you try to pass an integer to the reverse-string function:

user=> (reverse-string 12345)
ClassCastException clojure.lang. Numbers cannot be cast to
clojure.lang. IFn clojure.core/seq (core.clj:136)

To avoid this error, you can either make sure that the input to the reverse-string function is always a string, or you can modify the function to handle other types of input, such as integers, by first converting them to strings using the str function. For example, you could write the reverse-string function like this to handle both strings and integers as input:

(defn reverse-string [s]
(let [s (if (string? s) s (str s))]
  (apply str (reverse (seq s)))))

With this version of the function, if you pass an integer as input, the function will convert it to a string using the str function before calling the seq function on it, so the seq function will be able to work with the input. Here's an example of how you can use this modified version of the reverse-string function:

user-> (reverse-string "hello world")
"dlrow olleh"

user=> (reverse-string 12345)
"54321"

Note that the modified version of the function will also work for other types of input that can be converted to strings using the str function, such as floats and booleans.

me How would you use the concept of the Maybe monad in Haskell in this clojure function?

ChatGPT: The Maybe monad in Haskell is a way to represent computations that may or may not have & p a result, and it provides a way to compose these computations in a safe and predictable way. In Clojure, the Maybe monad is usually implemented as a Option type, which has two possible values: Some and None

In the context of the reverse-string function, you could use the Option type to represent the possibility that the input to the function might not be a string, in which case the function would return None instead of a reversed string. Here's an example of how you could use the Option type to modify the reverse-string function to handle the case where the input is not a string:

(defn reverse-string [s]
  (if (string? s)
    (Some (apply str (reverse (seq s))))
    None))

With this version of the reverse-string function, if the input is a string, the function will return a Some value containing the reversed string, and if the input is not a string, the function will return a None value. This allows the caller of the function to handle the case where the input is not a string in a predictable and safe way.

Here's an example of how you can use this modified version of the reverse-string function:

user=> (reverse-string "hello world")

Some "dlrow olleh"
user=> (reverse-string 12345)
None

Note that the Option type in Clojure does not provide the same syntactic sugar for composing computations as the Maybe monad in Haskell, so you cannot use the >>= operator to chain calls to the reverse-string function in the same way you can in Haskell. However, you can still use the Option type to represent computations that may or may not have a result, and you can use the match or case forms to pattern match on the Option values and handle the different cases in a predictable and safe way.

me How would you implement Option in clojure?

ChatGPT: In Clojure, the Option type is typically implemented as a sealed protocol, which is a type of polymorphic type that defines a set of concrete types that implement the protocol.

The Option protocol typically defines two concrete types: Some, which represents a computation that has a result, and None, which represents a computation that does not have a result.

Here's an example of how you could define the Option protocol and the Some and None types in Clojure:

(defprotocol Option
  (map [o f])
  (flat-map [o f]))

(deftype Some [x]
  Option
  (map [o f] (Some (f x)))
  (flat-map [o f] (f x)))

(deftype None [])
  Option
  (map [o f] None)
  (flat-map [o f] None))

The Option protocol defines two methods: map and flat-map The map method takes a function f as input and applies it to the value contained in the Some type, f it exists, or returns a None value f the Option type is None The flat-map method is similar to map but it allows the function f to return an Option value, which is then flattened into the outer Option value.

The Some type implements the Option protocol by providing concrete implementations f the map and flat-map methods. The 'map method applies the function f to the value x contained in the Some type, and returns a new Some value containing the result f the function. The flat-map method applies the function f to the value x contained in the Some type, and then flattens the resulting Option value into the outer Option value.

The None type also implements the Option protocol by providing concrete implementations of the map and flat-map methods. The map and flat-map methods simply return a None value in this case, since there is no value to apply the function to.

Here's an example of how you can use the Option protocol and the Some and None types:

user=> (def some-value (Some 12345))
#' user/some-value

user=> (map some-value inc)
Some 12346

user=> (flat-map some-value (fn [x] (Some (* × 2))))
Some 24690

user=> (map some-value (comp (partial * 2) inc))
Some 24690

user=> (def none-value None)
#'user/none-value

user=> (map none-value inc)
None

user=> (flat-map none-value (fn [x] (Some (* × 2))))
None

user=> (map none-value (comp (partial * 2) inc))
None

In this example, the some-value variable is defined as a Some value containing the integer 12345, and the none-value variable is defined as a None value. The map and flat-map functions are then used to apply different functions to the values contained in the Option types, and the…