Comments on codesimple: Join and split

Comment from puzza007: Er, no. Just tested that....

2007-07-31T12:06:00.000+01:00

Comment from puzza007:

Er, no. Just tested that. Second time's a charm:

join([E1, E2| Es], S) ->
[E1, S| join([E2| Es], S)];
join([E], _) ->
[E];
join([], _) ->
[].

Comment from puzza007: Here's my version of join....

2007-07-30T22:47:00.000+01:00

Comment from puzza007:

Here's my version of join. I can't believe that the lists module doesn't already have one!

join(List, Sep) ->
join(List, Sep, []).
join([H|T], Sep, Acc) ->
join(T, Sep, [H,Sep|Acc]);
join([], _Sep, Acc) ->
lists:reverse(Acc).

Comment from Michael Le Du: You can use string:to...

2007-06-21T14:54:00.000+01:00

Comment from Michael Le Du:

You can use string:tokens("a:b:b", ":"). to split the string

Comment from Christian S: Intersperse would be a ...

2007-06-21T14:28:00.000+01:00

Comment from Christian S:

Intersperse would be a fine addition to the 'lists'-
module. This is however the way i would express it:

-module(intersperse).
-export([intersperse/2, join/2]).

intersperse(_, []) ->
[];
intersperse(Delimiter, [Head|Rest]) ->
intersperse(Delimiter, Rest, [Head]).

intersperse(_Delimiter, [], Acc) ->
lists:reverse(Acc);
intersperse(Delimiter, [Head|Rest], Acc0) ->
Acc1 = [Head, Delimiter|Acc0],
intersperse(Delimiter, Rest, Acc1).

%% The need for this function is questionable, the name
%% join is also questionable as it is also the
%% name of a relational-db operation.
join(Delimiter, List) ->
lists:flatten(intersperse(Delimiter, List)).