concatStringsSep
lib.strings.concatStringsSep
Primop
Docs pulled from | This Revision | 12 minutes ago
Nixpkgs manual
Concatenate a list of strings with a separator between each element
Inputs
sep- Separator to add between elements
list- List of input strings
Type
concatStringsSep :: String -> [String] -> String
Examples
lib.strings.concatStringsSep usage example
concatStringsSep "/" ["usr" "local" "bin"]
=> "usr/local/bin"
Nix manual
Takes 2 arguments
separator, list
Concatenate a list of strings with a separator between each
element, e.g. concatStringsSep "/" ["usr" "local" "bin"] == "usr/local/bin".
Time Complexity
O(n + m) (amortized) where:
n = number of list elements m = total length of output string
Noogle detected
Implementation
This function is implemented in c++ and is part of the native nix runtime.
static void prim_concatStringsSep(EvalState & state, const PosIdx pos, Value ** args, Value & v)
{
NixStringContext context;
auto sep = state.forceString(
*args[0],
context,
pos,
"while evaluating the first argument (the separator string) passed to builtins.concatStringsSep");
state.forceList(
*args[1],
pos,
"while evaluating the second argument (the list of strings to concat) passed to builtins.concatStringsSep");
std::string res;
res.reserve((args[1]->listSize() + 32) * sep.size());
bool first = true;
for (auto elem : args[1]->listView()) {
if (first)
first = false;
else
res += sep;
res += *state.coerceToString(
pos,
*elem,
context,
"while evaluating one element of the list of strings to concat passed to builtins.concatStringsSep");
}
v.mkString(res, context, state.mem);
}
Implementation
The following is the current implementation of this function.
concatStringsSep = builtins.concatStringsSep;