Re: Map Vs Foreach

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Re^2: Map Vs Foreach by JavaFan (Canon) on Nov 26, 2009 at 21:04 UTC
They both "visit" each element of a list (I would say, they both execute a block of code for each element of a list). The main difference is that for is a statement, map is an expression. As such, map has (in non-void context) a return value. Only if you assign the return value of map to an array, and you have the same array as input list to the map, one could say that map 'transforms' a list. But then it's the combination of map and the assign statement. The only way I can think of map on its own "transforming" a list is constructs like: `map {$_ = ucfirst} @array;` [download] But for knows that trick as well: `for (@array) {$_ = ucfirst}` [download]	[reply] [d/l] [select]
Re^3: Map Vs Foreach by ikegami (Patriarch) on Nov 26, 2009 at 22:59 UTC
The both "visit" each element of a list I was talking about their purpose. The only way I can think of map on its own "transforming" a list is constructs like: The whole purpose of `map` is to transform a list. `my @b = map uc, @a; # 1 to 1 my @b = map { $_ => uc($_) } @a; # 1 to N, const ratio my @b = map { /^#/ ? () : $_ } @a; # 1 to N` [download] But then it's the combination of map and the assign statement No way. You don't have to assign the list to anything. You could pass it to `join`, for example. `print join '\|', map uc, qw( a b c );` [download]	[reply] [d/l] [select]
Re^4: Map Vs Foreach by JavaFan (Canon) on Nov 27, 2009 at 09:36 UTC
In my dictionary, that's as much "transforming" as addition "transforms" scalars. For me, something that doesn't change, isn't transforming - it's static.	[reply]
Re^5: Map Vs Foreach by ikegami (Patriarch) on Nov 27, 2009 at 16:12 UTC
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