what-is-going-on.jl

# I have the following bit of code
using Format
type MinimaxNode
  id :: Int
  min_node :: Bool
  val :: Int
  children :: Vector{MinimaxNode}
end

function f(old, # what type is this?
    ignored :: Int,
    depth :: Int,
    branch :: Range{Int},
    vrange :: Range{Int},
    mini :: Bool)
  (new, u) = raw_minimax(old[0], depth - 1, branch, vrange, !mini)
  push!(u, old[1])
  return (new, old[1])
end

function raw_minimax(ids, # this too
    depth :: Int,
    branch :: Range{Int},
    vrange :: Range{Int},
    mini :: Bool)
  if depth == 0
    u = MinimaxNode(first(ids), mini, rand(vrange), MinimaxNode[])
    return (drop(ids, 1), u)
    end
  id = first(ids)
  (ran, children) = foldl((x, y) -> f(x, y, depth, branch, vrange, mini),
    (drop(ids, 1), MinimaxNode[]),
    [1:rand(branch)])
  vals = map(x -> x.val, children)
  val = mini ? minimum(vals) : maximum(vals)
  return (ran, MinimaxNode(id, mini, val, children))
end                

function mk_minimax(depth :: Int,
    branch :: Range{Int},
    vrange :: Range{Int},
    mini :: Bool)
  (ignore, ans) = raw_minimax(countfrom(), depth, branch, vrange, mini)
  return ans
end

# Aside from the unknown types above being something of a mystery, when I try the following (after `include`ing):
#
# julia> x = mk_minimax(2, 2:3, -10:10, true)
# 
# I get this:
# ERROR: MethodError: no method matching f(::Tuple{Base.Drop{Base.Count{Int64}},Array{MinimaxNode,1}}, ::UnitRange{Int64}, 
# ::Int64, ::UnitRange{Int64}, ::UnitRange{Int64}, ::Bool)
# Closest candidates are:  f(::Any, ::Int64, ::Int64, ::Range{Int64}, ::Range{Int64}, ::Bool) at /home/koz/documents/uni/teaching/2017/ai/mk-minimax.jl:16 
# in mapfoldl_impl(::Base.#identity, ::##1#3{Int64,UnitRange{Int64},UnitRange{Int64},Bool}, ::Tuple{Base.Drop{Base.Count{Int64}},Array{MinimaxNode,1}}, ::Array{UnitRange{Int64},1}, ::Int64) at ./reduce.jl:46 
# in raw_minimax(::Base.Count{Int64}, ::Int64, ::UnitRange{Int64}, ::UnitRange{Int64}, ::Bool) at /home/koz/documents/uni/teaching/2017/ai/mk-minimax.jl:34 
# in mk_minimax(::Int64, ::UnitRange{Int64}, ::UnitRange{Int64}, ::Bool) at /home/koz/documents/uni/teaching/2017/ai/mk-minimax.jl:46 
# in eval_user_input(::Any, ::Base.REPL.REPLBackend) at ./REPL.jl:64 in macro expansion at ./REPL.jl:95 [inlined] 
# in (::Base.REPL.##3#4{Base.REPL.REPLBackend})() at ./event.jl:68
#
# What on earth is going on?