From c1d3cc12b920f60d06265b645daa3ff0010a8402 Mon Sep 17 00:00:00 2001
From: Connor Schembor <connor.schembor@rutgers.edu>
Date: Thu, 5 Nov 2020 21:28:32 -0500
Subject: Add product function to int and float modules

---
 src/gleam/float.gleam | 21 +++++++++++++++++++++
 src/gleam/int.gleam   | 21 +++++++++++++++++++++
 2 files changed, 42 insertions(+)

(limited to 'src')

diff --git a/src/gleam/float.gleam b/src/gleam/float.gleam
index 3d611b5..8018c95 100644
--- a/src/gleam/float.gleam
+++ b/src/gleam/float.gleam
@@ -190,3 +190,24 @@ fn do_sum(numbers: List(Float), initial: Float) -> Float {
     [x, ..rest] -> do_sum(rest, x +. initial)
   }
 }
+
+/// Multiplies a list of Floats and returns the product.
+///
+/// ## Example
+///
+///    > product([2.5, 3.2, 4.2])
+///    33.6
+///
+pub fn product(numbers: List(Float)) -> Float {
+  case numbers {
+    [] -> 0.
+    _ -> do_product(numbers, 1.)
+  }
+}
+
+fn do_product(numbers: List(Float), initial: Float) -> Float {
+  case numbers {
+    [] -> initial
+    [x, ..rest] -> do_product(rest, x *. initial)
+  }
+}
diff --git a/src/gleam/int.gleam b/src/gleam/int.gleam
index 0bbd63d..002a155 100644
--- a/src/gleam/int.gleam
+++ b/src/gleam/int.gleam
@@ -167,3 +167,24 @@ fn do_sum(numbers: List(Int), initial: Int) -> Int {
     [x, ..rest] -> do_sum(rest, x + initial)
   }
 }
+
+/// Multiplies a list of Ints and returns the product.
+///
+/// ## Example
+///
+///    > product([2, 3, 4])
+///    24
+///
+pub fn product(numbers: List(Int)) -> Int {
+  case numbers {
+    [] -> 0
+    _ -> do_product(numbers, 1)
+  }
+}
+
+fn do_product(numbers: List(Int), initial: Int) -> Int {
+  case numbers {
+    [] -> initial
+    [x, ..rest] -> do_product(rest, x * initial)
+  }
+}
-- 
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