42 lines
1.5 KiB
Plaintext
42 lines
1.5 KiB
Plaintext
& fn apply_command {
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& "Takes a turtle state and a command and calculates a new state."
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& (state, command) -> match command with {
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& (:goto, (x, y)) -> assoc (state, :position, (x, y))
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& (:home) -> do state >
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& assoc (_, :position, (0, 0)) >
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& assoc (_, :heading, 0)
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& (:clear) -> do state >
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& assoc (state, :position, (0, 0)) >
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& assoc (_, :heading, 0)
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& (:right, turns) -> update (state, :heading, add (_, turns))
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& (:left, turns) -> update (state, :heading, sub (_, turns))
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& (:forward, steps) -> {
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& let #{heading, position, ...} = state
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& let unit = heading/vector (heading)
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& let vect = mult (steps, unit)
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& update (state, :position, add (vect, _))
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& }
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& (:back, steps) -> {
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& let #{heading, position, ...} = state
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& let unit = heading/vector (heading)
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& let vect = mult (steps, unit)
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& update (state, :position, sub (_, vect))
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& }
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& (:penup) -> assoc (state, :pendown?, false)
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& (:pendown) -> assoc (state, :pendown?, true)
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& (:penwidth, pixels) -> assoc (state, :penwidth, pixels)
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& (:pencolor, color) -> assoc (state, :pencolor, color)
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& (:setheading, heading) -> assoc (state, :heading, heading)
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& (:loadstate, position, heading, visible?, pendown?, penwidth, pencolor) -> #{position, heading, visible?, pendown?, penwidth, pencolor}
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& (:show) -> assoc (state, :visible?, true)
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& (:hide) -> assoc (state, :visible?, false)
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& (:background, _) -> state
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& }
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& }
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fn many_args (_, _, x, _) -> x
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let fewer_args = many_args (:foo, :bar, _, :baz)
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fewer_args(:quux)
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