path.js

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path.js

import { addMap, lastK, } from 'fenugreek-collections';

pathEntry :: ( node, Number, Number ) -> {pred, length, weight} returns an object with pred, weight, and length properties

export const pathEntry = (pred = null, length = 1, weight = 0) => ({ pred, length, weight });
const pathVal = (pred = null) => (length = 1) => (weight = 0) =>
  ({ pred, length, weight });

¶

addSrc :: Map<pathEntry> -> node -> Map<pathEntry> adds a {node:{pred, weight, length}} entry to a path
```
export const appendPath = path => src => addMap(path)(src)(pathEntry(lastK(path), 1, 0));
```
¶

initPath :: node -> Map<pathEntry> initializes a new path given a source node
```
export const initPath = node => appendPath()(node);
```
¶

getWeight :: {weight:Number} -> Number returns an object with pred, weight, and length properties
```
export const getWeight = ({ weight = 0 }) => weight;
```
¶

getLength :: {length:Number} -> Number returns an object with pred, weight, and length properties
```
export const getLength = ({ length = 1 }) => length;
```
¶

lastVal :: Map<pathEntry> -> {pred, length, weight} returns the last entry in the path
```
export const lastVal = path => path.get(lastK(path));
```
¶

lastWeight :: Map<pathEntry> -> Number returns the last weight in the path
```
export const lastWeight = path => getWeight(lastVal(path));
```
¶

lastLength :: Map<pathEntry> -> Number returns the last length in the path
```
export const lastLength = path => getLength(lastVal(path));
```
¶

nextWeight :: Map<pathEntry> -> Number -> Number returns an object with pred, weight, and length properties
```
export const nextWeight = path => (w = 0) => lastWeight(path) + w;
```
¶

nextLength :: Map<pathEntry> -> Number -> Number returns an object with pred, weight, and length properties
```
export const nextLength = path => lastLength(path) ? lastLength(path) + 1 : 1;
```

nextPath :: (Map<pathEntry>, [node, Number]) -> Map<pathEntry> returns an object with pred, weight, and length properties

export const nextPath = (path = new Map, [ n, w = 0 ]) =>
  path.set(n, pathVal(lastK(path))(nextLength(path))(nextWeight(path)(w)));