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/lib.h b/lib.h
index a6684ca6..b4ea4af8 100644
--- a/lib.h
+++ b/lib.h
@@ -889,12 +889,12 @@ val rmember_if(val pred, val list, val key);
 val remq(val obj, val seq, val keyfun);
 val remql(val obj, val seq, val keyfun);
 val remqual(val obj, val seq, val keyfun);
-val remove_if(val pred, val seq, val keyfun);
+val remove_if(val pred, val seq, val keyfun_in, val mapfun_in);
 val keepq(val obj, val seq, val keyfun);
 val keepql(val obj, val seq, val keyfun);
 val keepqual(val obj, val seq, val keyfun);
-val keep_if(val pred, val seq, val keyfun);
-val keep_keys_if(val pred, val seq_in, val keyfun_in);
+val keep_if(val pred, val seq, val keyfun_in, val mapfun_in);
+val keep_keys_if(val pred, val seq_in, val keyfun_in, val mapfun_in);
 val separate(val pred, val seq, val keyfun);
 val separate_keys(val pred, val seq_in, val keyfun_in);
 val remq_lazy(val obj, val list);