メソッド連鎖（MC）対機能的パイプライン化（FP）

MC vs FPに関するノート

MCコン

fp pros :

ソースコード例

/*
@func
a non-typed pipe
- that can dynamically handle sync or async funcs

@usage
this is a util func of the typed pipe funcs

@param {...Function} fns - one or more funcs spread to an arr of funcs
@return {(v: *) => *} - the first func in the pipe takes in any data, and the last func returns any data
*/
export const pipeBase = (...fns) => v => {
  return fns.reduce((r, fn) => { // r = result or output of fn call
    if (isPromise(r)) {
      return r.then(fn);
    }
    return fn(r);
  }, v);
};

/**
@func
a strongly-typed pipe that is invoked with a supplied str

@clientcode
const p1 = pipeStr(f1, f2, f3);
p1("");

@param {...Function} fns
@return {(s: string) => *}
*/
export const pipeStr = (...fns) => s => throwIfNotStr(s) || pipeBase(...fns)(s);

/**
@func
split by \n chars

@notes
use forceSingleNewline() beforehand if str contains multiple blank lines in a row

@param {string} s
@return {string[]}
*/
export const splitByNewline = s => s.trim().split("\n");

/**
@func
trim each str in arr of strs

@notes
if the elem is a str, trim it
- otherwise leave it as is

@param {string[]} a
@return {string[]}
*/
export const mapTrim = a => a.map(s => isStr(s) ? s.trim() : s);

/**
@func
only remove empty str elems in an arr

@notes
applies trim() before comparing

@param {string[]} a
@return {string[]} arr with empty elems removed
*/
export const filterOutEmptyStrs = a => a.filter(s => isNotEmptyStr(s));

/**
@func complement
from the supplied arr, remove the elems that start with the supplied str chunk

@param {string} chunk
@return {(a: string[]) => string[]}
*/
export const filterNotStartsWith = chunk => a => fil(s => !s.startsWith(chunk), a);

/**
@func
make a single str where each elem is placed on a new line

@param {string[]} a
@return {string} concatentated
*/
export const joinByNewLine = a => a.join("\n");

/*
@func
replace a substring with another substring in a haystack of text

@cons
use the g flag to remove all matches
- otherwise it will just replace the first and return
case sensitive

@param {RegExp} n needleRegex
@param {string} r replacement
@return {(h: string) => string} // haystack -> a copy of the haystack with the needles replaced with the new values
*/
export const replaceByRegex = (n, r) => h => h.replace(n, r);

/**
@func util
supply a template string of bash commands
- and return the logged output

@param {string} a line-separated chain of bash commands
@return {string} chain of commands separated by &&
*/
export const chainCmds = pipeStr(
  splitByNewline,
  mapTrim,
  filterOutEmptyStrs,
  filterNotStartsWith("//"), //exclude comments
  joinByNewLine,
  replaceByRegex(/\n/g, " && "), lStr,
);

lBashExecChain(`
pwd
git config -l --local
git show-branch
git status
git stash list
git stash --include-untracked
git pull
git stash pop
lerna bootstrap
`);

最終ノート

ピーエス