104 lines
2.8 KiB
Fennel
104 lines
2.8 KiB
Fennel
(local { : view } (require :fennel))
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(local { : merge } (require :lume))
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;; who needs a test framework when you have lisp macros?
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(macro expect [text actual expected]
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`(let [actual# ,actual]
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(or (match actual#
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,expected true
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_# false)
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(assert false (view {
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:text ,text
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:expected ,expected
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:actual actual#
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})))))
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(fn rotate [direction rotation]
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(let [chooser
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(match rotation
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:r {
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:n :e
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:e :s
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:s :w
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:w :n
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}
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:l {
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:n :w
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:w :s
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:s :e
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:e :n
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})]
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(. chooser direction)))
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(fn command [rover string]
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(match string
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:f (match rover.direction
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:n (merge rover {:y (+ rover.y 1)})
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:s (merge rover {:y (- rover.y 1)})
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:w (merge rover {:x (- rover.x 1)})
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:e (merge rover {:x (+ rover.x 1)}))
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:r (merge rover {:direction (rotate rover.direction :r)})
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:l (merge rover {:direction (rotate rover.direction :l)})
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_ (assert false (. "unrecognised command " string))))
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(fn execute [rover [cmd & cmds]]
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(let [r1 (command rover cmd)]
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(if (next cmds)
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(r1:execute cmds)
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r1)))
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(fn rover [x y direction]
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{: x
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: y
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: direction
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: execute
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})
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(let [r (rover 7 15 :n)]
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(expect
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"rover knows (x,y) and the direction (N,S,E,W) it is facing"
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r
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{:x 7 :y 15 :direction :n}))
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(let [r (rover 0 0 :n)]
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(expect "The rover receives a character array of commands"
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(r:execute [:f :f :f])
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{}))
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(let [r (rover 0 0 :n)]
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(expect "Moves north when pointing north and asked to move forward"
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(r:execute [:f]) {:x 0 :y 1 :direction :n}))
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(let [r (rover 3 2 :s)]
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(expect "Moves south when pointing south and asked to move forward"
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(r:execute [:f]) {:x 3 :y 1 :direction :s}))
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(let [r (rover 0 0 :w)]
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(expect "Moves west when pointing west and asked to move forward"
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(r:execute [:f]) {:x -1 :y 0 :direction :w}))
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(let [r (rover 0 0 :e)]
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(expect "Moves east when pointing east and asked to move forward"
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(r:execute [:f]) {:x 1 :y 0 :direction :e}))
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(let [r (rover 1 1 :s)]
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(expect "The rover acts on multiple commands"
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(r:execute [:f :f :f])
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{:x 1 :y -2 :direction :s}))
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(let [r (rover 2 4 :e)]
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(expect "Rotates to south when pointing east and asked to turn right"
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(r:execute [:r]) {:x 2 :y 4 :direction :s}))
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(let [r (rover 2 4 :s)]
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(expect "Rotates to east when pointing south and asked to turn left"
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(r:execute [:l]) {:x 2 :y 4 :direction :e}))
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(let [r (rover 2 4 :w)]
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(expect "Rotates to north when pointing west and asked to turn right"
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(r:execute [:r]) {:x 2 :y 4 :direction :n}))
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(print "OK")
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