93 lines
2.3 KiB
Plaintext
93 lines
2.3 KiB
Plaintext
// complex data is passed and manipulated in structures
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struct World {
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// each member is defined by name and type
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u32 xsize,
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u32 ysize,
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BitArray current,
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u32 numdots,
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BitArray next,
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// members can have default initialization values
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i32 xmin = 1'000'000,
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i32 xmax = -1,
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i32 ymin = 1'000'000,
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i32 ymax = -1,
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}
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// non-associated function, operates in the scope of its arguments only
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// `fn fn_name(args) return_value { body }`
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fn count_neighbors(BitArray array, i32 i, i32 j) i32 {
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// local variables are declared with `let`
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let c1 = i - 1;
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let c2 = i;
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let c3 = i + 1;
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let r1 = i - 1;
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let r2 = i;
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let c3 = i + 1;
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// associated functions of a struct can be stored in a variable
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// now `g(x, y)` is shorthand for `array.get(x, y)`
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let g = array.get;
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// return result with trailing expression at the end of function
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g(c1, r1) + g(c1, r2) + g(c1, r3) +
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g(c2, r1) + g(c2, r3) +
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g(c3, r1) + g(c3, r2) + g(c3, r3)
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}
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// associated function for the World struct
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World fn set_next(i32 i, i32 j) {
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// members on this World struct can be accessed with `.`
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var numdots = .numdots; // mutable variables are defined with `var`
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let neighbors = count_neighbors(.current, i, j);
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// `if` statements are expressions
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let next = if .current.get(i, j) == 0 {
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if neighbors != 3 {
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0
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} else {
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numdots++;
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1
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}
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} else {
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// Python-like `or` operator
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if neighbors == 2 or neighbors == 3 {
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1
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} else {
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numdots--;
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0
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}
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};
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if next != 0 {
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// TODO: mutability rules for arguments?
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if i < .xmin { .xmin = i; }
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if i > .xmax { .xmax = i; }
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if j < .ymin { .ymin = j; }
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if j > .ymax { .ymax = j; }
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}
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}
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World fn next_cycle() {
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let xlb = .xmin - 1;
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let xub = .xmax + 1;
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let ylb = .ymin - 1;
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let yub = .ymax + 1;
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// TODO: flesh out `for` semantics
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for y in ylb..yub {
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for x in xlb..xub {
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.set_next(x, y);
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}
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}
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// TODO: figure out better range definitions, or ditch them altogether
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for y in 0..(.ysize) {
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for x in 0..(.xsize) {
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// TODO: mutability rules
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.current.set_bit(x, y, .next.get_bit(x, y));
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}
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}
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}
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