concat(n)

📦
version 9.0.3 · 3 versions
, in alpine 3.23, alpine 3.24, fedora 43, fedora 44, nixos 26.05, nixpkgs unstable

💖 concat(n) 💖

ok so bestie, welcome to concat — it's a built-in command from the Tcl Built-In Commands manual, and it's literally the glue stick of Tcl. ✨

🌸 NAME 🌸

concat — join lists together 🫶

✨ SYNOPSIS ✨

concat ?arg arg ...?

🎀 DESCRIPTION 🎀

okay so here's the vibe: this command takes each of its arguments and joins them all together with spaces, but first it trims the leading and trailing white-space off of every single one of them. 🧹✨

and like — if all of the arguments are lists, then this has the exact same effect as concatenating them into one single list. no cap. 💅

arguments that end up empty (like, after the trimming happens) are just ignored entirely. they don't get a seat at the table, they're not invited, bye. 🙈

it permits any number of arguments, bestie — zero, one, a hundred, whatever. and if you supply no args at all, the result is just an empty string. that's it. that's the whole thing. 🌈

🔥 EXAMPLES 🔥

so even though concat will concatenate lists and flatten them in the process, like in this little interactive session right here:

% concat a b {c d e} {f {g h}}
a b c d e f {g h}

...it will also concatenate stuff that isn't even a list, which you can see from this next session:

% concat " a b {c   " d "  e} f"
a b {c d e} f

and note — note this, fr fr — the concatenation does not remove spaces from the middle of values. look:

% concat "a   b   c" { d e f }
a   b   c d e f

(i.e., there are three spaces between each of the a, the b and the c. yes really. count them. 🫣)

so if you want true list concatenation, you should use the list command with expansion of each input list:

% list {*}"a   b   c" {*}{ d e f }
a b c d e f

see?? that one actually collapsed the spaces. main character behavior. 👑

🌈 SEE ALSO 🌈

⭐ KEYWORDS ⭐

concatenate, join, list

ok that's the whole page bestie!! this one's from the <strong>Tcl 8.3</strong> era, dated way back, and it's filed under the <strong>concat(n)</strong> page in the Tcl manual set. go forth and glue your lists together 💖✨🎀🦋

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