// this function will call the function passed as "funct" if the temp is in the allowed range. Otherwise it will return "Error"
let validate funct temp =
   match temp with
   | temp when (temp > -217 && temp < 1000) -> funct temp
   | _ -> "Error"

// This is a really simple Frozen/Not Frozen function which doesn't check for a valid temp range
let frozen temp =
   match temp with
   | temp when (temp > 0) -> "Not Frozen"
   | _ -> "Frozen"

// here, we wrap the simple function with the one which checks for valid ranges
let wrapped = validate frozen

[<EntryPoint>]
let main args =
   printfn "-300: %s" (wrapped -300)
   printfn "-200: %s" (wrapped -200)
   printfn "   0: %s" (wrapped 0)
   printfn "unwrapped -300: %s" (frozen -300)
   0