29 lines
939 B
JavaScript
29 lines
939 B
JavaScript
import { assign } from "../generics/generics.js";
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import { makeGeneric } from "../generics/generics.js";
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import { fnType } from "../metacircular.js";
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import { Double, Int } from "../primitives/symbols.js";
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import { getMul, NumInstances } from "./num.js";
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import { numDictType } from "./num_type.js";
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const square = numDict => x => getMul(numDict)(x)(x);
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const squareFnType = makeGeneric(a =>
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fnType({
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in: numDictType(a),
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out: fnType({
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in: a,
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out: a,
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}),
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}));
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console.log("should be: Int -> Int");
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console.log(assign(squareFnType, makeGeneric(() => numDictType(Int))));
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console.log("should be: Double -> Double");
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console.log(assign(squareFnType, makeGeneric(() => numDictType(Double))));
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// to call 'square' we need:
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// - access to a mapping from types to their typeclass instantiation
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// - to know that our argument is 'Int'
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console.log("");
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console.log(square(NumInstances.get(Int))(42n)); // 1764n
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