keep-if, remove-if, keep-keys-if: mapfun argument.

We introduce a mapfun argument to these functions so that they
can additionally transform the accumulated values.

The keep-keys-if function is now implemented through the same
helper function as keep-if but with the mapfun argument
defaulting to a copy of the keyfun argument.

* eval.c (eval_init): Update registrations of remove-if,
keep-if and keep-keys-if to new arities of C functions.

* lib.c (rem_if_impl): Implement new optional mapfun
parameter.
(remove_if, keep_if): Add mapfun parameter.
(keep_keys_if): Implement via rem_if_impl, and add
mapfun argument. We do the defaulting of keyfun here,
so that we can then use that argument's value to default
mapfun.

* lib.h (remove_if, keep_if, keep_keys_if): Declarations
updated.

* tests/012/seq.tl: Couple of test cases exercising mapfun
argument of keep-if and remove-if.

* txr.1: Documented.

1 files changed, 3 insertions, 3 deletions

diff --git a/eval.c b/eval.c
index 066e1c1c..c1bb2c51 100644
--- a/eval.c
+++ b/eval.c
@@ -7428,12 +7428,12 @@ void eval_init(void)
   reg_fun(intern(lit("remq"), user_package), func_n3o(remq, 2));
   reg_fun(intern(lit("remql"), user_package), func_n3o(remql, 2));
   reg_fun(intern(lit("remqual"), user_package), func_n3o(remqual, 2));
-  reg_fun(intern(lit("remove-if"), user_package), func_n3o(remove_if, 2));
+  reg_fun(intern(lit("remove-if"), user_package), func_n4o(remove_if, 2));
   reg_fun(intern(lit("keepq"), user_package), func_n3o(keepq, 2));
   reg_fun(intern(lit("keepql"), user_package), func_n3o(keepql, 2));
   reg_fun(intern(lit("keepqual"), user_package), func_n3o(keepqual, 2));
-  reg_fun(intern(lit("keep-if"), user_package), func_n3o(keep_if, 2));
-  reg_fun(intern(lit("keep-keys-if"), user_package), func_n3o(keep_keys_if, 2));
+  reg_fun(intern(lit("keep-if"), user_package), func_n4o(keep_if, 2));
+  reg_fun(intern(lit("keep-keys-if"), user_package), func_n4o(keep_keys_if, 2));
   reg_fun(intern(lit("separate"), user_package), func_n3o(separate, 2));
   reg_fun(intern(lit("separate-keys"), user_package), func_n3o(separate_keys, 2));
   reg_fun(intern(lit("remq*"), user_package), func_n2(remq_lazy));