/Prelude-v23.0.0/Integer/multiply.dhall

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multiply m n computes m * n.

Examples

multiply +3 +5 ≡ +15
multiply -3 +5 ≡ -15
multiply -3 -5 ≡ +15
multiply +0 +5 ≡ +0
multiply +5 +0 ≡ +0
multiply +0 +0 ≡ +0
multiply +1 +5 ≡ +5
multiply +3 -1 ≡ -3

Source

--| `multiply m n` computes `m * n`.
let nonPositive =
missing sha256:e00a852eed5b84ff60487097d8aadce53c9e5301f53ff4954044bd68949fac3b
? ./nonPositive.dhall

let multiplyNonNegative =
λ(x : Integer) →
λ(y : Integer) →
Natural/toInteger (Integer/clamp x * Integer/clamp y)

let multiply
: Integer → Integer → Integer
= λ(m : Integer) →
λ(n : Integer) →
if nonPositive m
then if nonPositive n
then multiplyNonNegative (Integer/negate m) (Integer/negate n)
else Integer/negate (multiplyNonNegative (Integer/negate m) n)
else if nonPositive n
then Integer/negate (multiplyNonNegative m (Integer/negate n))
else multiplyNonNegative m n

let example0 = assert : multiply +3 +5 ≡ +15

let example1 = assert : multiply -3 +5 ≡ -15

let example2 = assert : multiply -3 -5 ≡ +15

let example3 = assert : multiply +0 +5 ≡ +0

let example4 = assert : multiply +5 +0 ≡ +0

let example5 = assert : multiply +0 +0 ≡ +0

let example6 = assert : multiply +1 +5 ≡ +5

let example7 = assert : multiply +3 -1 ≡ -3

in multiply