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Recursion: Start with the Base Case
Thanks to Eric Grimson for this idea. When you’re writing a recursive function… Write the base case first. That’s where it returns a value, instead of recursing. To show this, let’s write a factorial function. A factorial is a “product of all positive integers less than or equal to n,” according to Wikipedia. The factorial…
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Loop in Clojure
Here’s a way to avoid recursive helper functions… By using loop in Clojure. Sometimes recursive helper functions seem needed, like fibonacci-iter: (I ported this to Clojure from Structure and Interpretation of Computer Programs, licensed CC BY-SA-4.0) That fibonacci-iter helper function is only needed for recursion. For example, the public (defn fibonacci [n] only needs an…
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Testing Problems Come From Architecture
Thanks to Logicroom for teaching me this. With testing problems, the fix is rarely in the tests. The fix is in the architecture. Most tests should be unit tests. With only some “integrated tests” (J.B. Rainsberger) at the edges. But usually, the system is too coupled to have unit tests. The tests make real REST…