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Detecting Victory: REPL Experimentsλ︎

Find a winning rowλ︎

To find a winning row we can compare the values in the vector with each other

#_(apply = [:cross :cross :cross])
;; => true

#_(apply = [:nought :nought :nought])
;; => true

#_(apply = [:empty :cross :empty])
;; => false

#_(apply = [:cross :nought :empty])
;; => false

However, this approach also matches an :empty row or column

#_(apply = [:empty :empty :empty])
;; => true

Using an anonymous function over the collection allows us to compare each value, if all values are not= :empty then we can return true

(apply  (fn [cell-value] (not= :empty cell-value))[:empty :cross :cross])

As we will probably call this multiple times, lets convert it into a named function.

(defn cell-empty?
  [cell-value] (not= :empty cell-value))

Hmm, still not idea, as any combination that does not contain :empty will return true

(cell-empty? [[:cross :nought :cross]])

Applying both checks will give the right results

(defn winning-line? [cell-row]
   (apply = cell-row)
   (apply cell-empty? cell-row)))

#_(winning-line? [:cross :cross :cross])
;; => true

#_(winning-line? [:nought :nought :nought])
;; => true

#_(winning-line? [:cross :nought :cross])
;; => false

#_(winning-line? [:empty :empty :empty])
;; => false

#_(winning-line? [:empty :nought :cross])
;; => false