From 38fc122b84fce3a0e6299069524e80a73818d928 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Mon, 10 Apr 2023 13:19:19 +0100
Subject: Constraint operator* collection helper to IterableCollections

---
 lib/collections.hpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'lib')

diff --git a/lib/collections.hpp b/lib/collections.hpp
index 59cec6f..4df622e 100644
--- a/lib/collections.hpp
+++ b/lib/collections.hpp
@@ -65,10 +65,11 @@ operator*=(IterableCollection auto & in, auto && f)
 }
 
 template<template<typename...> typename C, typename... T>
+	requires IterableCollection<C<T...>>
 [[nodiscard]] constexpr auto
 operator*(const C<T...> & in, auto && f)
 {
-	C<decltype(f(in[0]))> out;
+	C<decltype(f(*in.begin()))> out;
 
 	std::transform(in.begin(), in.end(), std::inserter(out, out.end()), f);
 	return out;
-- 
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