Merge pull request #358 from EvgSkv/ti2023

Time type.

Author: EvgSkv

README.md

@@ -174,6 +174,49 @@ $ logica primes.l run Prime
 +-------+
 ```
 
+### Cities with largest beer variety
+
+Let's use beer variety dataset from [plotly](https://github.com/plotly/datasets/blob/master/beers.csv).
+
+Let us find top 5 states with largest variety of beers. In each state we will pick city with the largest
+variety in the state.
+
+Program `beer.l`:
+
+```
+@Engine("duckdb");
+
+@Ground(Beer);
+Beer(..r) :- 
+    `('https://github.com/plotly/datasets/blob/master/beers.csv?raw=true')`(..r);
+
+BeersInState(state) += 1 :- Beer(state:);
+BeersInCity(state, city) += 1 :- Beer(state:, city:);
+
+ArgMax5(x) = ArgMaxK(x, 5);
+BestCityForBeer(state:, city:,
+                city_beers: BeersInCity(state, city),
+                state_beers: BeersInState(state)) :-
+    state in ArgMax5{s -> BeersInState(s)},
+    city = ArgMax{c -> BeersInCity(state, c)};
+```
+
+Running `beer.l`:
+
+```
+# logica beer.l run BestCityForBeer
++-------+--------------+------------+-------------+
+| state | city         | city_beers | state_beers |
++-------+--------------+------------+-------------+
+| IN    | Indianapolis | 43         | 139         |
+| CO    | Boulder      | 41         | 265         |
+| CA    | San Diego    | 42         | 183         |
+| TX    | Austin       | 25         | 130         |
+| MI    | Grand Rapids | 66         | 162         |
++-------+--------------+------------+-------------+
+```
+
+<!--
 ### News mentions
 
 Who was mentioned in the news in 2020 the most?
@@ -211,7 +254,7 @@ $ logica mentions.l run Mentions
 
 Note that cities of Los Angeles and Las Vegas are mentioned in this table due to known
 missclasification issue in the GDELT data analysis.
-
+--> 
 ## Feedback
 
 Feel free to create [github issues](https://github.com/EvgSkv/logica/issues)

compiler/dialect_libraries/duckdb_library.py

@@ -54,6 +54,13 @@
 Num(a) = a;
 Str(a) = a;
 
+Epoch(a) = epoch :-
+  epoch = SqlExpr("epoch_ns({a})", {a:}) / 1000000000,
+  a ~ Time, 
+  epoch ~ Num;
+TimeDiffSeconds(a, b) = Epoch(SqlExpr("{a} - {b}", {a:, b:}));
+ToTime(a) = SqlExpr("cast({a} as timestamp)", {a:});
+
 NaturalHash(x) = ToInt64(SqlExpr("hash(cast({x} as string)) // cast(2 as ubigint)", {x:}));
 
 # This is unsafe to use because due to the way Logica compiles this number

compiler/dialects.py

@@ -416,7 +416,9 @@ def BuiltInFunctions(self):
           'Greatest': 'GREATEST(%s)',
           'ToString': 'CAST(%s AS TEXT)',
           'DateAddDay': "DATE({0}, {1} || ' days')",
-          'DateDiffDay': "CAST(JULIANDAY({0}) - JULIANDAY({1}) AS INT64)"
+          'DateDiffDay': "CAST(JULIANDAY({0}) - JULIANDAY({1}) AS INT64)",
+          'CurrentTimestamp': 'GET_CURRENT_TIMESTAMP()',
+          'TimeAdd': '{0} + to_microseconds(cast(1000000 * {1} as int64))'
       }
 
     def DecorateCombineRule(self, rule, var):

type_inference/research/infer.py

@@ -416,7 +416,7 @@ def ActMindingRecordLiterals(self, node):
   def ActMindingTypingPredicateLiterals(self, node):
     if 'type' in node and 'literal' in node and 'the_predicate' in node['literal']:
       predicate_name = node['literal']['the_predicate']['predicate_name']
-      if predicate_name in ['Str', 'Num', 'Bool']:
+      if predicate_name in ['Str', 'Num', 'Bool', 'Time']:
         reference_algebra.Unify(node['type']['the_type'],
                                 reference_algebra.TypeReference(predicate_name))
 
@@ -700,6 +700,8 @@ def PsqlType(self, t):
       return 'numeric'
     if t == 'Bool':
       return 'bool'
+    if t == 'Time':
+      return 'timestamp'
     if isinstance(t, dict):
       return RecordTypeName(reference_algebra.RenderType(t))
     if isinstance(t, list):

type_inference/research/reference_algebra.py

@@ -210,12 +210,14 @@ def Rank(x):
     return 4
   if x == 'Bool':
     return 5
-  if isinstance(x, list):
+  if x == 'Time':
     return 6
-  if isinstance(x, OpenRecord):
+  if isinstance(x, list):
     return 7
-  if isinstance(x, ClosedRecord):
+  if isinstance(x, OpenRecord):
     return 8
+  if isinstance(x, ClosedRecord):
+    return 9
   assert False, 'Bad type: %s' % x
 
 
@@ -276,7 +278,7 @@ def Unify(a, b):
         Incompatible(b.target, a.target))
     return
 
-  if concrete_a in ('Num', 'Str', 'Bool'):
+  if concrete_a in ('Num', 'Str', 'Bool', 'Time'):
     if concrete_a == concrete_b:
       return  # It's all fine.
     # Type error: a is incompatible with b.

type_inference/research/types_of_builtins.py

@@ -77,6 +77,9 @@ def TypesOfBultins():
             0: 'Str',
             'logica_value': 'Str'
         },
+        'Time': {
+            'logica_value': 'Time'
+        },
         'Agg+': {
             0: 'Num',
             'logica_value': 'Num'
@@ -248,6 +251,9 @@ def TypesOfBultins():
            0: x,
            1: x,
            'logica_value': x
+        },
+        'CurrentTimestamp': {
+           'logica_value': 'Time'
         }
     }
     types_of_predicate['<'] = types_of_predicate['<='] = types_of_predicate['>='] = types_of_predicate['>']