Prefix string matching

[andreas]

I wonder if the following expression:

    add_prefix(String = "prefix" ++ _) ->
        String;
    add_prefix(Path) ->
        "prefix" ++ String.

is  equal to:

    add_prefix(String = [$p,$r,$e,$f,$i,$x|_]) ->
        String;
    add_prefix(Path) ->
        "prefix" ++ String.


Can the compiler optimize:

    "Const" ++ VariableString

to:

    [$C, $o, $n, $s, $t | VariableString]


If the compiler can not optimize this, how costly is ++ operations in pattern matching?


Regards,
Andreas Hillqvist
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