Different approach: optional arguments on hash-isec and hash-uni allow

for more flexible joining of data from the hash tables.

* eval.c (eval_init): Remove hash_guni and hash_gisec. Change
registration for hash_uni and hash_isec to three arguments with
one optional.

* hash.c (hash_uni): Third parameter introduced, join_func.
The default behavior changes: in the two argument case,
clashing keys prefer the value from hash1 rather than hash2.
For this reason, we now iterate over hash2 first, then hash1.
(hash_guni): Removed.
(hash_isec): Third parameter introduced, join_func.
(hash_gisec): Removed.

* hash.h (hash_uni, hash_isec): Declarations updated.
(hash_guni, hash_gisec): Delarations removed.

* txr.1: Documentation updated.

1 files changed, 2 insertions, 4 deletions

diff --git a/eval.c b/eval.c
index 7a6fa19e..e32ed23b 100644
--- a/eval.c
+++ b/eval.c
@@ -2508,11 +2508,9 @@ void eval_init(void)
   reg_fun(intern(lit("hash-values"), user_package), func_n1(hash_values));
   reg_fun(intern(lit("hash-pairs"), user_package), func_n1(hash_pairs));
   reg_fun(intern(lit("hash-alist"), user_package), func_n1(hash_alist));
-  reg_fun(intern(lit("hash-uni"), user_package), func_n2(hash_uni));
-  reg_fun(intern(lit("hash-guni"), user_package), func_n2(hash_guni));
+  reg_fun(intern(lit("hash-uni"), user_package), func_n3o(hash_uni, 2));
   reg_fun(intern(lit("hash-diff"), user_package), func_n2(hash_diff));
-  reg_fun(intern(lit("hash-isec"), user_package), func_n2(hash_isec));
-  reg_fun(intern(lit("hash-gisec"), user_package), func_n2(hash_gisec));
+  reg_fun(intern(lit("hash-isec"), user_package), func_n3o(hash_isec, 2));
   reg_fun(intern(lit("group-by"), user_package), func_n2v(group_by));
   reg_fun(intern(lit("hash-update"), user_package), func_n2(hash_update));