Revert "Add builtins.imap function"

This reverts commit 4db99ea955.

src/libexpr/primops/imap.cc

@@ -1,46 +0,0 @@
-#include "nix/expr/primops.hh"
-
-namespace nix {
-
-static void prim_imap(EvalState & state, const PosIdx pos, Value ** args, Value & v)
-{
-    auto shift = state.forceInt(*args[0], pos, "while evaluating the first argument passed to 'builtins.imap'").value;
-    Value & f = *args[1];
-    Value & list = *args[2];
-
-    state.forceList(list, pos, "while evaluating the third argument passed to 'builtins.imap'");
-
-    if (list.listSize() == 0) {
-        v = list;
-        return;
-    }
-
-    auto outList = state.buildList(list.listSize());
-    for (const auto & [n, v] : enumerate(outList)) {
-        v = state.allocValue();
-        auto vIdx = state.allocValue();
-        vIdx->mkInt(n + shift);
-        Value * args[] = {vIdx, list.listView()[n]};
-        state.callFunction(f, args, *v, pos);
-    }
-
-    v.mkList(outList);
-}
-
-static RegisterPrimOp primop_imap(
-    {.name = "__imap",
-     .args = {"shift", "f", "list"},
-     .doc = R"(
-       Apply the function *f* to each element in the list *list*. The function *f* is called with two arguments: the index of the element (plus *shift*) and the element itself.
-
-       For example,
-
-       ```nix
-       builtins.imap 1 (i: v: "${v}-${toString i}") ["a" "b"]
-       ```
-
-       evaluates to `[ "a-1" "b-2" ]`.
-     )",
-     .fun = prim_imap});
-
-} // namespace nix

src/libexpr/primops/meson.build

@@ -9,5 +9,4 @@ sources += files(
   'fetchMercurial.cc',
   'fetchTree.cc',
   'fromTOML.cc',
-  'imap.cc',
 )

tests/functional/lang/eval-okay-imap.exp

@@ -1 +0,0 @@
-[ "a-0" "b-1" "a-1" "b-2" ]

tests/functional/lang/eval-okay-imap.nix

@@ -1,8 +0,0 @@
-(builtins.imap 0 (i: v: "${v}-${toString i}") [
-  "a"
-  "b"
-])
-++ (builtins.imap 1 (i: v: "${v}-${toString i}") [
-  "a"
-  "b"
-])