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Comment by codygman | Hacker News Reader

    mapM_ putStrLn ["hat", "dog", "cat"]

I'd say the above is pretty simple if explained after:

    putStrLn "hello world"

You don't really have to go into Monads for this to be understood/used. You can just leave it at "you use functions ending with an M if they do something like print out to the screen or get stuff from a web page".

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My first reaction to this was that this was definitely less understandable, but I realized there were two pieces to this. One is banal - mapM_ and putStrLn are not near as simple as `for' and `print' (the latter have English meanings directly).

The second piece is interesting: Is something of the sort "<mapfn> <printfn> <list>" easier to explain to someone who's new to programming than "<foreach> <print>"? I've always thought the latter was easier to understand, but I'm curious which one someone who has no previous programming experience would grasp more immediately.

Right, I think that once the concept is taught of what mapM does/means it will be easier to keep applying than something like a foreach loop.

The reason being that "<mapfn> <somefn> <list>" is more declarative, whereas the foreach loop is ambiguous. Something we often take for granted is how hard it was at first to come up with what exactly we need to do or mutate inside that loop to build the right result.

If nothing else, there is interesting discussion to be had ;)

This is because of lexical issues. You can define aliases for mapM_ and putStrLn and get something more approachable to the lexically challenged.

repeat print ["foo"; "bar"; "etc"]

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