Joeri Exelmans
8eec5b9239
big part of the code base still needs to be 'ported' to the updated type constructors.
62 lines
1.7 KiB
JavaScript
62 lines
1.7 KiB
JavaScript
// Sum-type (also called: tagged union, disjoin union, variant type)
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// A Sum-type always has only two variants, called "left" and "right".
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// Sum-types of more variants (called Enums) can be constructed by nesting Sum-types.
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import { prodType } from "./types.js";
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import { GenericType, Type } from "../primitives/types.js";
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import { typedFnType } from "./types.js";
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import { makeGeneric } from "../generics/generics.js";
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import { sumType } from "./types.js";
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export const newLeft = left => ({t: "L", v: left }); // 't': tag, 'v': value
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export const newRight = right => ({t: "R", v: right});
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// signature:
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// sum-type -> (leftType -> resultType, rightType -> resultType) -> resultType
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export const match = sum => handlers =>
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sum.t === "L"
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? handlers.l(sum.v)
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: handlers.r(sum.v);
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export const ModuleSum = {l:[
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// binary type constructor
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// Type -> Type -> Type
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...typedFnType(sumType, fnType =>
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fnType
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(() => Type)
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(() => fnType
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(() => Type)
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(() => Type)
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),
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),
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// // a -> a | b
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// ...typedFnType(newLeft, fnType =>
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// makeGeneric((a, b) =>
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// fnType
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// (a)
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// (sumType(() => a)(() => b))
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// ), GenericType),
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// // b -> a | b
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// ...typedFnType(newRight, fnType =>
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// makeGeneric((a, b) =>
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// fnType
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// (b)
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// (sumType(() => a)(() => b))
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// ), GenericType),
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// // a | b -> (a -> c, b-> c) -> c
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// ...typedFnType(match, fnType =>
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// makeGeneric((a, b, c) =>
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// fnType
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// (() => sumType(() => a)(() => b))
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// (() => fnType
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// (() => prodType
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// (() => fnType(() => a)(() => c))
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// (() => fnType(() => b)(() => c))
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// )
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// (() => c)
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// )
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// ), GenericType),
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]};
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