Sync

Task/Matrix-transposition/Lua/matrix-transposition-2.lua

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+function map(f, a)
+  local b = {}
+  for k,v in ipairs(a) do b[k] = f(v) end
+  return b
+end
+
+function mapn(f, ...)
+  local c = {}
+  local k = 1
+  local aarg = {...}
+  local n = table.getn(aarg)
+  while true do
+    local a = map(function(b) return b[k] end, aarg)
+    if table.getn(a) < n then return c end
+    c[k] = f(unpack(a))
+    k = k + 1
+  end
+end
+
+function apply(f1, f2, a)
+ return f1(f2, unpack(a))
+end
+
+xy = {{1,2,3,4},{1,2,3,4},{1,2,3,4}}
+yx = apply(mapn, function(...) return {...} end, xy)
+print(table.concat(map(function(a) return table.concat(a,",") end, xy), "\n"),"\n")
+print(table.concat(map(function(a) return table.concat(a,",") end, yx), "\n"))