How to eliminate ternary operators or if-else with fp-ts

[elamurugan-r]

Hi,
I have the below code (similar) in my project. I used ternary operator. I want to avoid it as it looks imperative.

  const key = 'heaven';
  const isComp = key === 'heaven';
  export const getX = (paramM: Option<Param>) =>
  pipe(
    paramM,
    O.chain((param) => param.arr),
    O.chain(
      isComp ? RA.findFirst((x: string) => x === "react") : RA.head
    ),
    O.getOrElse(() => "javascript")
  );

Can someone help me on this?

[JLambertazzo]

folding an option based on isComp is a pretty clean way to achieve this. This implementation for example:

// helper function based on isComp, boolean -> ReadonlyArray<string> -> Option<string>
const firstMatchOrHead = (isComp: boolean) => (roa: ReadonlyArray<string>) =>
  pipe(
    isComp,
    O.fromPredicate(identity),
    O.fold(
      () => RA.head(roa),
      () => RA.findFirst((x) => x === "react")(roa)
    )
  );

// main function from above, Option<Param> -> string
const getX = (paramM: Option<Param>) =>
  pipe(
    paramM,
    O.chain((p) => p.arr),
    O.chain(firstMatchOrHead(isComp)),
    O.getOrElse(constant("javascript"))
  );

[bigpopakap]

You can also achieve the same thing with boolean.fold():

import * as B from 'fp-ts/boolean';

pipe(
  isComp,
  B.fold(
    () => RA.head(roa),
    () => RA.findFirst((x) => x === "react")(roa)
  ),
)

In general, if you find yourself doing O.fromPredicate(identity), O.fold() you can just replace that with B.fold directly

Apologies for bad code formatting... I'm writing this on my phone

[elamurugan-r]

Hey Everyone,
I tried the below and it worked:

pipe(
    paramM,
    O.chain((param) => param.arr),
    O.chain(parr => 
	pipe(
	    isComp,
            O.fromPredicate(x => x),
            O.chain(() => RA.findFirst((x: string) => x === "react")(parr)),
            O.alt(() => RA.head(parr))
       )
   ),
   O.getOrElse(() => "javascript")
)