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utilities.js
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utilities.js
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import { blue, gray, red } from "https://deno.land/std@0.79.0/fmt/colors.ts";
import append from "https://deno.land/x/ramda@v0.27.2/source/append.js";
import curry from "https://deno.land/x/ramda@v0.27.2/source/curry.js";
import lift from "https://deno.land/x/ramda@v0.27.2/source/lift.js";
import reduce from "https://deno.land/x/ramda@v0.27.2/source/reduce.js";
const $$decoder = new TextDecoder();
const $$encoder = new TextEncoder();
/**
* ## Utilities
*
* ### `assertIsArray`
* `* -> Boolean`
*
* ### `assertIsBoolean`
* `* -> Boolean`
*
* ### `assertIsFunction`
* `* -> Boolean`
*
* ### `assertIsInstance`
* `* -> Boolean`
*
* ### `assertIsNull`
* `* -> Boolean`
*
* ### `assertIsNumber`
* `* -> Boolean`
*
* ### `assertIsObject`
* `* -> Boolean`
*
* ### `assertIsRegex`
* `* -> Boolean`
*
* ### `assertIsString`
* `* -> Boolean`
*
* ### `assertIsUndefined`
* `* -> Boolean`
*
* ### `decodeRaw`
* `Uint8Array -> String`
*
* ### `encodeText`
* `String -> Uint8Array`
*/
export const assertIsArray = value => value instanceof Array;
export const assertIsBoolean = value => value === true || value === false;
export const assertIsFunction = value => value instanceof Function;
export const assertIsInstance = curry((T, value) => value instanceof T);
export const assertIsNull = value => value === null;
export const assertIsNumber = value => typeof value === "number";
export const assertIsObject = value => typeof value === "object" && !(value instanceof Array);
export const assertIsRegex = value => value instanceof RegExp;
export const assertIsString = value => typeof value === "string";
export const assertIsUndefined = value => value === undefined;
export const decodeRaw = $$decoder.decode.bind($$decoder);
export const encodeText = $$encoder.encode.bind($$encoder);
/**
* ### `chainLift`
* `(a -> b -> c) -> Chainable a -> Functor b -> Chainable c`
*
* This function is similar to [`lift`](https://ramdajs.com/docs/#lift) but is chainable.
*
* ```js
* import Task from "https://deno.land/x/functional@v1.3.0/library/Task.js";
* import { chainLift } from "https://deno.land/x/functional@v1.3.0/library/utilities.js";
*
* const hogeFuga = useWith(
* chainLift(curry((x, y) => Task.of(x * y))),
* [
* x => Task.of(x),
* x => Task.of(x)
* ]
* );
*
* const container = await hogeFuga(42, 24).run();
*
* const value = safeExtract("Failed.", container);
*
* assertEquals(value, 1008);
* ```
*/
export const chainLift = curry(
(binaryFunction, chainableFunctor, functor) => chainableFunctor.chain(x => functor.map(binaryFunction(x)))
);
/**
* ### `chainRec`
* `ChainRec r => ((a -> c, b -> c, a) -> r c) -> a -> r b`
*
* This function is a combinator for the [`chainRec` algebra](https://github.com/fantasyland/fantasy-land#chainrec).
* It takes a ternary function, an initial value and, a chainable recursive functor.
*
* ```js
* import Task from "https://deno.land/x/functional@v1.3.0/library/Task.js";
* import { chainRec } from "https://deno.land/x/functional@v1.3.0/library/utilities.js";
*
* const multiplyAll = curry((x, n) => chainRec(
* (Loop, Done, cursor) =>
* cursor === n ? Done(Pair(cursor, null)) : Loop(Pair(cursor + 1, Task.of([ x * (cursor + 1) ]))),
* 0
* ));
*
* const container = await multiplyAll(42, 10)(Task.of([ 0 ])).run();
*
* const value = safeExtract("Failed.", container);
*
* assertEquals(value, [ 0, 42, 84, 126, 168, 210, 252, 294, 336, 378, 420 ]);
* ```
*/
export const chainRec = curry(
(ternaryFunction, initiator, chainableRecursiveFunctor) =>
(chainableRecursiveFunctor.chainRec || chainableRecursiveFunctor["fantasy-land/chainRec"])
.call(chainableRecursiveFunctor, ternaryFunction, initiator)
);
/**
* ### `evert`
* `Applicative a => a -> a[] -> a`
*
* This function takes a type constructor and, a list of Applicative functor and evert it; effectively making an Applicative
* functor of a list of value.
*
* ```js
* import Task from "https://deno.land/x/functional@v1.3.0/library/Task.js";
* import { evert } from "https://deno.land/x/functional@v1.3.0/library/utilities.js";
*
* const container = await evert(Task, [ Task.of(42), Task.of(32), Task.of(24) ]).run();
*
* const list = safeExtract("Failed.", container);
*
* assertEquals(list, [ 42, 32, 24 ]);
* ```
*/
export const evert = curry(
(T, list) => list.reduce(
(accumulator, x) => lift(append)(x, accumulator),
T.of([])
)
);
export const insideOut = evert;
/**
* ### `log`
* `String -> a -> a`
*
* This function is a composable `console.debug`. It takes a message, a value and, return the value.
*/
export const log = message => x => console.debug(blue(message), x) || x;
/**
* ### `runSequentially`
* `Chain c => (...c) -> c`
*
* This function takes n Chainable functor and chain them automatically.
*
* ```js
* import Task from "https://deno.land/x/functional@v1.3.0/library/Task.js";
* import { runSequentially } from "https://deno.land/x/functional@v1.3.0/library/utilities.js";
*
* const fuga = converge(
* runSequentially,
* [
* x => Task.of(x * 2),
* x => Task.of(x + 2)
* ]
* );
*
* const container = await fuga(42).run();
*
* const value = safeExtract("Failed.", container);
*
* assertEquals(value, 44);
* ```
*/
export const runSequentially = (initialChainableFunctor, ...chainableFunctorList) => reduce(
(accumulator, chainableFunctor) => accumulator.chain(_ => chainableFunctor),
initialChainableFunctor,
chainableFunctorList
);
/**
* ### `safeExtract`
* `String -> Either a -> a`
*
* This function takes a message and an Either container; if the container is `Either.Right`, the value will be
* returned. But if the container is `Either.Left`, it will throw an error with the message passed.
*/
export const safeExtract = curry(
(message, container) => container.fold({
Left: error => {
throw new Error(`${message} Error: ${
(error.hasOwnProperty('raw'))
? decodeRaw(error.raw)
: `${red(error.message)}\n${gray(error.stack)}`
}`)
},
Right: value => value
})
);
/**
* ### `stream`
* `((a, b) -> a) -> a -> AsyncIterable b -> a`
*/
export const stream = curry(
async (composedFunction, accumulator, iterator) => {
for await (const data of iterator) {
accumulator = composedFunction(accumulator, data);
}
return accumulator;
}
);