95 lines
2.8 KiB
Standard ML
95 lines
2.8 KiB
Standard ML
#!/usr/bin/env fun
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/*
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* This file is part of the Fun programming language.
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* https://hanez.org/project/fun/
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*
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* Copyright 2025 Johannes Findeisen <you@hanez.org>
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* Licensed under the terms of the ISC license.
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* https://opensource.org/license/isc-license-txt
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*/
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/*
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* Classes demo: fields, methods (with explicit 'this'), and usage.
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*
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* Notes:
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* - Define a class with `class Name`
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* - Fields are initialized with simple assignments inside the class body.
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* - Methods are written as `fun method(this, ...) { ... }` with 'this' required as the first parameter.
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* - Instantiation: p = Name()
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* - Method calls: load the method function from the instance into a variable, then call it with the instance as the first argument.
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* Example:
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* move_fn = p["move"]
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* move_fn(p, dx, dy)
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*/
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class Point(number x, number y)
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x = 0
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y = 0
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/* private helper (callable only as this._shift inside class) */
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fun _shift(this, dx, dy)
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this.x = this.x + dx
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this.y = this.y + dy
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return 0
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fun move(this, dx, dy)
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/* delegate to private helper */
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this._shift(dx, dy)
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print("typeof(this._shift) = " + typeof(this._shift))
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return 0
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fun toString(this)
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return "Point(" + to_string(this.x) + ", " + to_string(this.y) + ")"
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class Counter
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value = 0
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fun inc(this)
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this.value = this.value + 1
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return this.value
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fun add(this, n)
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this.value = this.value + n
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return this.value
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// Instantiate a Point with constructor parameters
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p = Point(10, -2)
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// Types
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print("typeof(Point) = " + typeof(Point)) // Class (factory)
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print("typeof(p) = " + typeof(p)) // Point(10, -2) (instance)
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// Read/write fields
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print("p.x = " + to_string(p["x"]) + ", p.y = " + to_string(p["y"]))
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// Call methods directly with dot-call sugar: p.method(args) desugars to method(p, args)
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print("toString(p) => " + p.toString())
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p.move(3, 5)
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print("after move(3,5) -> " + p.toString()) // expect Point(13, 3)
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/* External private call should fail with AccessError and halt */
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// This fails because of calling a private method, prefixed with "_" in the class definition. Commented out to make the
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// script run without any errors.
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//p._shift(1, 1)
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// Another instance (explicit constructor args)
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q = Point(0, 0)
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print("q initially -> " + q.toString()) // Point(0, 0)
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// Counter demo
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c = Counter()
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print("counter inc -> " + to_string(c.inc())) // 1
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print("counter inc -> " + to_string(c.inc())) // 2
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print("counter add(5) -> " + to_string(c.add(5))) // 7
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print("counter current value = " + to_string(c["value"]))
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/* Expected output:
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typeof(Point) = Class
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typeof(p) = Point(10, -2)
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p.x = 10, p.y = -2
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toString(p) => Point(10, -2)
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typeof(this._shift) = Function
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after move(3,5) -> Point(13, 3)
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q initially -> Point(0, 0)
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counter inc -> 1
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counter inc -> 2
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counter add(5) -> 7
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counter current value = 7
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*/
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