43 lines
1.3 KiB
JavaScript
43 lines
1.3 KiB
JavaScript
import { Bool, Int } from "../primitives/types.js";
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import { fnType, lsType } from "../structures/types.js";
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import { assign, makeGeneric, unify } from "./generics.js";
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import { pretty } from "../util/pretty.js";
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// a -> Int
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const a_to_Int = makeGeneric(a => fnType(a)(Int));
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// Bool -> Int
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const Bool_to_Int = makeGeneric(() => fnType(lsType(Bool))(Int));
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console.log("should be: [Bool] -> Int")
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console.log(pretty(unify(a_to_Int, Bool_to_Int)));
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// (a -> a) -> b
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const fnType2 = makeGeneric((a,b) => fnType(fnType(a)(a))(b));
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// (Bool -> Bool) -> a
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const fnType3 = makeGeneric(a => fnType(fnType(Bool)(Bool))(a));
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console.log("should be: (Bool -> Bool) -> a");
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console.log(pretty(unify(fnType2, fnType3)));
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// (a -> b) -> [a] -> [b]
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const mapFnType = makeGeneric((a,b) =>
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fnType
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(fnType(a)(b))
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(fnType(lsType(a))(lsType(b))))
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// a -> a
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const idFnType = makeGeneric(a =>
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fnType(a)(a));
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console.log("should be: [a] -> [a]");
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console.log(pretty(assign(mapFnType, idFnType)));
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// (a -> Int) -> [a] -> a
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const weirdFnType = makeGeneric(a =>
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fnType
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(fnType(a)(Int))
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(fnType
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(lsType(a))
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(a)))
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// we call this function with parameter of type (b -> b) ...
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// giving these substitutions:
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// a := b
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// b := Int
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console.log("should be: [Int] -> Int");
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console.log(pretty(assign(weirdFnType, idFnType)));
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