From a942d79869f1fcad66571614d66d536a3d7f8589 Mon Sep 17 00:00:00 2001
From: Peter Harpending <peterharpending@qpq.swiss>
Date: Sat, 11 Oct 2025 15:04:00 -0600
Subject: [PATCH] snowflakes work except define

---
 src/wfc.erl              |  3 ++-
 src/wfc_bm.erl           |  2 +-
 src/wfc_eval_context.erl | 57 +++++++++++++++++++++++++++++++++++++++-
 src/wfc_sftt.erl         | 17 ++++++++----
 4 files changed, 71 insertions(+), 8 deletions(-)

diff --git a/src/wfc.erl b/src/wfc.erl
index 79331d2..616a303 100644
--- a/src/wfc.erl
+++ b/src/wfc.erl
@@ -13,7 +13,8 @@
     reps/1,
     reps/2,
     add/1,
-    mul/1
+    mul/1,
+    zero/0, one/0
 ]).
 
 
diff --git a/src/wfc_bm.erl b/src/wfc_bm.erl
index 52b390d..878ad5c 100644
--- a/src/wfc_bm.erl
+++ b/src/wfc_bm.erl
@@ -219,7 +219,7 @@ dot({bm, {rc, 1, Same}, Bits1}, {bm, {rc, Same, 1}, Bits2}) ->
     parity(SummandBits).
 
 
--spec mand(bitstring(), bitstring()) -> bitstring().
+-spec mand(bm(), bm()) -> bm().
 % @doc bitwise-and two matrices of the same shape
 
 mand({bm, Shape, Bits1}, {bm, Shape, Bits2}) ->
diff --git a/src/wfc_eval_context.erl b/src/wfc_eval_context.erl
index d8cfda2..d686282 100644
--- a/src/wfc_eval_context.erl
+++ b/src/wfc_eval_context.erl
@@ -32,7 +32,62 @@ default() ->
 
 default_snowflakes() ->
     #{<<"and">>     => fun wfc:mul/1,
-      <<"xor">>     => fun wfc:add/1}.
+      <<"xor">>     => fun wfc:add/1,
+      <<"ior">> =>
+            fun IOR([S1 | Rest]) ->
+                    case IOR(Rest) of
+                        {ok, S2} -> {ok, sf_ior(S1, S2)};
+                        Error    -> Error
+                    end;
+                IOR([]) ->
+                    {ok, wfc:one()}
+            end,
+      <<"not">> =>
+            fun ([S]) -> {ok, sf_not(S)};
+                (Bad) -> {error, wfc_utils:str("not/1: wrong number of arguments: ~p", [Bad])}
+            end,
+      <<"implies">> =>
+            fun ([A, B]) -> {ok, sf_implies(A, B)};
+                (Bad)    -> {error, wfc_utils:str("implies/2: wrong number of arguments: ~p", [Bad])}
+            end,
+      <<"impliedby">> =>
+            fun ([A, B]) -> {ok, sf_impliedby(A, B)};
+                (Bad)    -> {error, wfc_utils:str("impliedby/2: wrong number of arguments: ~p", [Bad])}
+            end,
+      <<"iff">> =>
+            fun ([A, B]) -> {ok, sf_iff(A, B)};
+                (Bad)    -> {error, wfc_utils:str("iff/2: wrong number of arguments: ~p", [Bad])}
+            end
+     }.
+
+sf_ior(A, B) ->
+    wfc_sftt:appl_ttf(fun ttf_ior/2, [A, B]).
+
+sf_not(A) ->
+    {ok, Result} = wfc:add([wfc_sentence:one(), A]),
+    Result.
+
+sf_implies(A, B) ->
+    wfc_sftt:appl_ttf(fun ttf_implies/2, [A, B]).
+
+sf_impliedby(A, B) ->
+    sf_implies(B, A).
+
+sf_iff(A, B) ->
+    {ok, Result} = wfc:mul([sf_implies(A, B), sf_impliedby(A, B)]),
+    Result.
+
+ttf_ior(0, 0) -> 0;
+ttf_ior(1, 0) -> 1;
+ttf_ior(0, 1) -> 1;
+ttf_ior(1, 1) -> 1.
+
+ttf_implies(0, 0) -> 1;
+ttf_implies(1, 0) -> 0;
+ttf_implies(0, 1) -> 1;
+ttf_implies(1, 1) -> 1.
+
+
 
 define(Pat, Sentence, Ctx = #ctx{patterns = OldPatterns}) ->
     NewPatterns = maps:put(Pat, Sentence, OldPatterns),
diff --git a/src/wfc_sftt.erl b/src/wfc_sftt.erl
index 9f8fddf..435db20 100644
--- a/src/wfc_sftt.erl
+++ b/src/wfc_sftt.erl
@@ -12,7 +12,7 @@
     arity/1,
     tt/1, sf/1,
     sf_to_tt/1, tt_to_sf/1,
-    eval/2,
+    appl_ttf/2, appl/2,
     bfls/1,
     bfl/2
 ]).
@@ -73,11 +73,18 @@ sf(List) ->
     {sf, wfc_bm:col(List)}.
 
 
--spec eval(sf() | tt(), [wfc:sentence()]) -> wfc:sentence().
+-spec appl_ttf(fun(), [wfc:sentence()]) -> wfc:sentence().
 
-eval(TT = {tt, _}, Sentences) ->
-    eval(tt_to_sf(TT), Sentences);
-eval(SF = {sf, SFBM}, Sentences) ->
+appl_ttf(Fun, Sentences) ->
+    SF = ttfun_to_sf(Fun),
+    appl(SF, Sentences).
+
+
+-spec appl(sf() | tt(), [wfc:sentence()]) -> wfc:sentence().
+
+appl(TT = {tt, _}, Sentences) ->
+    appl(tt_to_sf(TT), Sentences);
+appl(SF = {sf, SFBM}, Sentences) ->
     Arity = arity(SF),
     Arity = length(Sentences),
     % [0, 0, 0], [1, 0, 0], ...