How about finding triples a

    [(a,b,c) for a in range(1,30)
             for b in range(a+1,30)
             if gcd(a,b)==1
             for c in range(b+1,30)
             if gcd(a,c)==1 and gcd(b,c)==1
             for d in [int((a**3+b**3+c**3)**(1.0/3)+0.5)]
             if a**3+b**3+c**3==d**3]

I doubt that would look any nicer with higher order functions. Specially if you want to get the same efficiency: notice how here we test that gcd(a,b)==1 as soon as possible. In general efficient comprehensions involve pushing any filtering as early as possible, so with higher order functions you get an alternation of filter with map/flatmap.

Here's a (probably lame) attempt at a Python higher order version:

    flatmap = lambda f, l: [x for t in l for x in f(t)]
    
    flatmap(lambda a: flatmap(lambda b: flatmap(lambda c: (lambda d: [(a,b,c)] if a**3+b**3+c**3==d**3 else [])(int((a**3+b**3+c**3)**(1.0/3)+0.5)) if gcd(a,c)==1 and gcd(b,c)==1 else [], range(b+1, 30)) if gcd(a,b)==1 else [], range(a+1,30)), range(1,30))
    

Maybe it would look nicer with some filters thrown in instead of abusing flatmap of empty lists, but it would be longer since you definitely need a flatmap for a and b, and either a flatmap or map for c.

I'd love to see a cleaner version with higher order function.

the a:b notation for JS is still in proposal phase https://github.com/tc39/proposal-slice-notation/pull/32, but I'll use it below to create ranges

I don't understand your `+0.5`, I've written below the transcription for your description

    [...1:30].map(a => 
      [...a+1:30].filter(b => gcd(a,b)==1).map(b => 
        [...b+1:30].filter(c => gcd(a,c)==1
          && gcd(b,c)==1 
          && Number.isInteger((a**3+b**3+c**3)**(1/3))
        .map(c => [a, b, c])
      )
    ).flat(2)

Or another equivalent way:

    [...1:30].flatMap(a => 
      [...a+1:30].filter(b => gcd(a,b)==1).flatMap(b => 
        [...b+1:30].filter(c => gcd(a,c)==1 
          && gcd(b,c)==1 
          && Number.isInteger((a**3+b**3+c**3)**(1/3)))
        .flatMap(c => [[a, b, c]])

Or another way (generating first all the triples):

    [...1:30].flatMap(a => [...a+1:30].flatMap(b => [...b+1:30].flatMap(c => [[a, b, c]])))
      .filter(([a, b, c]) => gcd(a,b)==1 && gcd(a,c)==1
                          && gcd(b,c)==1 && Number.isInteger((a**3+b**3+c**3)**(1/3)))

with https://github.com/tc39/proposal-iterator-helpers, which would allow lazy evaluation, and make more sense than above

    (1:30).flatMap(a => (a+1:30).flatMap(b => (b+1:30).flatMap(c => [[a, b, c]])))
      .filter(([a, b, c]) => gcd(a,b)==1 && gcd(a,c)==1
                          && gcd(b,c)==1 && Number.isInteger((a**3+b**3+c**3)**(1/3)))

without the slice-notation, it's really ugly (hence the proposal in the first link)

    Array.from({length: 30},(_,a)=>a+1)
      .flatMap(a=>Array.from({length: 30-a-1},(_,b)=>a+b+1)
        .flatMap(b => Array.from({length: 30-b-1},(_,c)=>b+c+1).flatMap(c => [[a, b, c]])))
    .filter(([a, b, c]) => gcd(a,b)==1 && gcd(a,c)==1
                          && gcd(b,c)==1 && Number.isInteger((a**3+b**3+c**3)**(1/3)))