↻ /prog/ Challenge [Vol. λfx.f x] ↻

THE CHALLENGE: Write a program that, given a number n, prints the expansion of (a+b)^n.

Example: 4 → a^4 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4

HOWEVER: You must do the above in a language you do not have any experience with. Never programmed in Haskell before? Gather some documentation and go for it.

_{(Well, you're advised to do that. I can't possibly know whether or not you know a programming language.)}

>>17
: fact 1+ 1 tuck +do i * loop ;

: combs ( n i -- nCi )
  over fact over fact / -rot - fact / ;

: .power ( var exponent -- )
  dup 0 > if
    over emit
    dup 1 > if ." ^" dup 0 .r then
  then 2drop ;

: binomexp ( exponent -- )
  dup for
    dup i combs dup 1 > if dup 0 .r then drop
    'a i .power
    'b over i - .power
    ."  "
  next drop ;

Works on GForth.