Dave Liepmann daveliepmann

Converting Java to Clojure for Non-Java Folks

Some simplified examples of how to read Java and turn it into Clojure. Intended for Clojurists without a background in Java. Based on clojure.org's Java Interop reference.

Consider reading: https://stackoverflow.com/questions/11993077/difference-between-static-methods-and-instance-methods

Calling methods of an instance

Say we come across some Java that calls a method on a string literal:

Speech at the American Legion

Hans Liepmann, circa 1946-8

During the long weary days and nights I spent in the Army, I had ample time to think about my American citizenship. I knew Germany under the Kaiser, during the Weimar Republic, in the beginning of Hitler’s regime and I saw it again at the end of it. Therefore, I had quite some occasion to compare it with America and maybe some of my experiences and observations will be interesting for you to hear. I consider it a great honor to be asked by the American Legion to talk to you and I thank the chairman very much.

You heard in the introduction a short outline of my story but I may be permitted to say a few more words about it. In 1933, when Hitler was chancellor, I received a letter from the government that from the next day on I, being a Jewish physician, was not permitted any longer to take care of patients who were members of the medical insurance companies. That was not so terribly bad in itself. But at that

When to use `assert`?

In JVM Clojure, Exceptions are for operating errors ("something went wrong") and Assertions are for programmer and correctness errors ("this program is wrong").

An assert might be the right tool if throwing an Exception isn't enough. Use them when the assertion failing means

there's a bug in this program (not a caller)
what happens next is undefined

S&C targets for an Ultimate (Frisbee) player

Each athlete must decide which areas of interest get prioritized in a particular training block. Note that exercises like RDLs and lunges are useful for multiple goals.

[Performance, pre-hab] Plyometrics & Sprints

These are of the highest importance. Consider them almost mandatory. Bouncing, jumping, bounding, skipping, and maximal sprints are critical to develop tissue resilience and to maintain or improve the athletic qualities most important in Ultimate.

Winter training conditions might make it tough to find a place to run, so plyometrics must take up the slack by being part of every workout.

Train them in multiple directions, not just straight forward. Most plyometrics should be extensive, not intensive. Stay fresh; never try to train these through fatigue.

	;; 300x300 seems to be about where performance starts to degrade.

	(let [i (cell (interval :frame inc))]
	(cell
	(apply layer
	(for [x (range 0 300 20)
	y (range 0 300 20)]
	(let [angle (* (/ 3.14 180) (+ @i x y))]
	(position (+ x (* 15 (Math/cos angle)))
	(+ y (* 15 (Math/sin angle)))

	;; make sure your ns has `(:import [org.tensorflow DataType Graph Output Session Tensor])`
	;; or if in REPL, evaluate `(import [org.tensorflow DataType Graph Output Session Tensor])` first

	;; Construct a graph to add two float Tensors, using placeholders.
	(let [g (Graph.)
	s (Session. g)
	x (-> (.opBuilder g "Placeholder" "x")
	(.setAttr "dtype" DataType/FLOAT)
	(.build)
	(.output 0))

	(ns sample.load-edn
	"Load EDN from asset on startup"
	(:require
	["package:flutter/material.dart" :as m]
	["package:flutter/widgets.dart" :as f.widgets]
	["package:flutter/services.dart" :as f.services]
	[cljd.flutter :as f]
	[cljd.reader]))