2024-06-11 21:37:04 +00:00
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& Lesson 11: `spingons` and recursion
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& Here's our friend, the ngon
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fn ngon! (n, size) -> repeat n { fd! (size); rt! (div (1, n)) }
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& Here we're introducing one of the more important, and """difficult""" concepts in computer science, recursion
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& Let's read this line-by-line
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2024-06-18 15:53:31 +00:00
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fn spin_gon! (n, size, angle, growth, times) -> {
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if lte? (times, 0)
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2024-06-11 21:37:04 +00:00
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then :ok & this is the base case: what to do when we're done
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& in this case, `:ok`--just a little signal all went well
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else {
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ngon! (n, size) & make an ngon
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rt! (angle) & turn right
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spin_gon! (n, mult (size, growth), angle, growth, sub (times, 1))
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& ^^^^^^^^^ This is the recursive call
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& `spin_gon!` calls itself!--make another spin_gon
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& What does this change between invocations?
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& * `mult (size, growth)`
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& * `sub (times, 1)` (or we could use `dec (times)`)
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& What would happen if we *didn't* make these changes?
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}
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}
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& Play with `spin_gon!`: see what you can come up with.
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& Also: see if you can't read what each call does.
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& It's okay if you can't: 5 parameters is a lot.
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& Clayson's examples:
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& Example 1, p. 21
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& spin_gon! (30, 2, 0.03, 1.02, 95)
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& Example 2, p. 21
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& repeat 3 {
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& spin_gon! (4, 120, 0, 0.95, 50)
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& rt! (0.25)
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& }
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& spin_gon! (4, 120, 0, 0.95, 19)
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