day2

aoc.bqn

@@ -1,6 +1,11 @@
+# a‿b Sub x: the b-length subarray starting at a
+Sub ⇐ {a‿b𝕊𝕩:b↑a↓𝕩}
+
+# e Split xs: split xs on occurrences of e (default 0)
+Split ⇐ {Sub⟜𝕩¨ ((1+») ⋈¨ ⊢-») /(𝕨⊣0)=𝕩}
+
 Day1 ⇐ {
-  nums ← •BQN⎊0¨ •FLines 𝕩
-  sums ← ∨ (+´ {𝕩↑𝕨↓nums}´)¨ (»⋈¨ ⊢-») /0=nums
-  ⟨⊑sums, +´ 3↑sums⟩
+  sums ← ∨+´¨ Split •BQN⎊0¨ •FLines 𝕩
+  ⟨⊑sums, +´3↑sums⟩
 }
 •Show Day1 ⊑•args

aoc.m

@@ -31,6 +31,8 @@ main2(!IO) :-
 :- pred solution(int::in, sol::out(sol)) is semidet.
 :- import_module day1.
 solution(1, day1.run).
+:- import_module day2.
+solution(2, day2.run).
 
 :- pred run_day(int, part, list(string), univ).
 :- mode run_day(in, in, in, out) is cc_multi.

day2.m

@@ -0,0 +1,112 @@
+% this could be probably like ¼ the length
+% but i wanted to write grammars and bidirectional predicates ok
+% leave me alone
+
+:- module day2.
+:- interface.
+:- import_module basics.
+:- import_module list.
+:- import_module univ.
+
+:- pred run(part::in, list(string)::in, univ::out) is cc_multi.
+
+:- implementation.
+:- import_module int.
+:- import_module char.
+:- import_module string.
+:- import_module pair.
+
+:- type move  ---> rock; paper; scissors.
+:- type moves == pair(move).
+
+:- type result ---> me; you; draw.
+:- type move_res == pair(move, result).
+
+:- type chars == list(char).
+
+:- type parser(T) == (pred(T, chars, chars)).
+:- mode parser(I) == (pred(out(I), in, out) is semidet).
+:- mode parser    == parser(ground).
+
+:- pred hand1(move::out, chars::in, chars::out) is semidet.
+hand1(rock)     --> ['A'].
+hand1(paper)    --> ['B'].
+hand1(scissors) --> ['C'].
+
+:- pred hand2(move::out, chars::in, chars::out) is semidet.
+hand2(rock)     --> ['X'].
+hand2(paper)    --> ['Y'].
+hand2(scissors) --> ['Z'].
+
+:- pred result(result::out, chars::in, chars::out) is semidet.
+result(you)  --> ['X'].
+result(draw) --> ['Y'].
+result(me)   --> ['Z'].
+
+:- pred two(parser(T)::parser, parser(U)::parser,
+            T::out, U::out,
+            chars::in, chars::out) is semidet.
+two(P, Q, A, B) --> P(A), [' '], Q(B).
+
+:- pred line1(moves::out, chars::in, chars::out) is semidet.
+line1(A - B) --> two(hand1, hand2, A, B).
+
+:- pred line2(move_res::out, chars::in, chars::out) is semidet.
+line2(A - B) --> two(hand1, result, A, B).
+
+
+:- pred parse_line(parser(T)::parser, string::in, T::out) is semidet.
+parse_line(P, Str, X) :- P(X, to_char_list(Str), []).
+
+
+:- pred to_int(move, int).
+:- mode to_int(in,   out) is det.
+:- mode to_int(out,  in)  is semidet.
+to_int(rock,     1).
+to_int(paper,    2).
+to_int(scissors, 3).
+
+:- func to_int(move) = int.
+to_int(A) = B :- to_int(A, B).
+
+
+:- pred win(move, move, result).
+:- mode win(in, in,  out) is det.
+:- mode win(in, out, in)  is det.
+%   you       me
+win(rock,     rock,     draw).
+win(rock,     paper,    me).
+win(rock,     scissors, you).
+win(paper,    rock,     you).
+win(paper,    paper,    draw).
+win(paper,    scissors, me).
+win(scissors, rock,     me).
+win(scissors, paper,    you).
+win(scissors, scissors, draw).
+
+:- func win_score(result) = int.
+win_score(me)   = 6.
+win_score(you)  = 0.
+win_score(draw) = 3.
+
+:- func score1(move, move) = int.
+score1(You, Me) = to_int(Me) + win_score(Res) :- win(You, Me, Res).
+
+:- func score2(move, result) = int.
+score2(You, Res) = to_int(Me) + win_score(Res) :- win(You, Me, Res).
+
+:- func sum(list(int)) = int.
+sum(Xs) = foldl(plus, Xs, 0).
+
+
+:- pred run(list(string)::in, parser(pair(T, U))::parser,
+            (func(T, U) = int)::in, int::out) is det.
+run(Lines, P, F, Out) :-
+  if map(parse_line(P), Lines, Res) then
+    Out = sum(map(func(X - Y) = F(X, Y), Res))
+  else
+    die("invalid input"). % lol
+
+:- pragma no_determinism_warning(run/3).
+run(one, Lines, univ(Out)) :- run(Lines, line1, score1, Out).
+run(two, Lines, univ(Out)) :- run(Lines, line2, score2, Out).