Ramda Conventions

This page gathers rules followed by Ramda developers that have sublimed over the years of creating the library.

Contents

• Naming conventions
• Designing a function

Naming Conventions

Determine between suffixes With and By for a name of a function properly

Function with the suffix By must take a unary function to derive information from data it needs to return a result.

// Bad
minWith(x => mod(x), [-1, 2, 5, -7])

// Good
minBy(x => mod(x), [-1, 2, 5, -7])

On contrary, the suffix With is used for functions that take a function with arity greater than N where N > 1 to be applied to N items from data above which the function operates.

// Bad
uniqBy((a, b) => length(a) === length(b))([[1, 2], '12', 1, 2])

// Good
uniqWith((a, b) => length(a) === length(b))([[1, 2], '12', 1, 2])

Notes:

• Function sortWith can take list of predicates.
• Neither startsWith or endsWith does apply this convention.

Reference

• #65
• #2706

Designing a function

Always write pure functions

// Bad
log('Hello') // logs to console

// Good
logBy(window.console)('Hello')

Reference

• Pure function
• Functions that accept and return objects should respect frozenness #2238

Support currying

// Bad
add(1, 2) !== add(1)(2)

// Good
add(1, 2) === add(1)(2)

Reference

• Currying

Prefer non-variadic functions over variadic

// bad
sum(1, 2, 3) // 6

// good
sum([1, 2, 3]) // 6

Use imperative constructs to improve performance

// bad
const incAll = (xs) => xs.map(x => x + 1) 

// good
const incAll = (xs) => {
  let ys = [];
  for (let i = 0; i<xs.length; i++) {
    ys.push(xs[i] + 1);
  }
  return ys;
}

Reference

• jsperf
• jsbench.me
• JavaScript performance test

Determine if your function should support transducers

Ramda's often overlooked feature is support for transducers. Take in consideration if your function should support it too.

Reference

• all, any, aperture, chain, countBy, ...
• Transducers are coming
• The Transducer Protocol