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Versions: 208
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Stored size: 1.58 KB
Contents
datatype allergen = Eggs
| Peanuts
| Shellfish
| Strawberries
| Tomatoes
| Chocolate
| Pollen
| Cats
(* valueOf = fn: allergen -> int
Given an allergen returns which power of 2 it represents
e.g. Eggs => 0 means that Eggs = 2^0 = 1
*)
fun valueOf a =
case a of
Eggs => 0
| Peanuts => 1
| Shellfish => 2
| Strawberries => 3
| Tomatoes => 4
| Chocolate => 5
| Pollen => 6
| Cats => 7
(* isAllergicTo = fn : int -> allergen -> bool
Given a code (integer) and an allergen returns true if the person
represented by the code is allergic to the specified allergen
*)
fun isAllergicTo code a =
let fun testAllergy code n =
let val codeWord = Word.fromInt(code)
val nWord = Word.fromInt(n)
val oneWord = Word.fromInt(1)
in (* ((code >> n) & 1) == 1 *)
oneWord = Word.andb(
Word.>>(codeWord, nWord),
oneWord
)
end
in
testAllergy code (valueOf a)
end
(* allergies = fn: int -> allergen list
Given a code that represents a person's allergies
return a list of all allergens that they are allergic to
*)
fun allergies code =
List.filter (isAllergicTo code) [Eggs, Peanuts, Shellfish, Strawberries, Tomatoes, Chocolate, Pollen, Cats]
Version data entries
208 entries across 208 versions & 1 rubygems