🐐 Connect 4 game

.gitignore

@@ -2,5 +2,8 @@
 __pycache__/
 .pytest_cache/
 
+examples/*
+!examples/*.cent
+
 .claude/
 CLAUDE.md

cent

@@ -1,16 +1,16 @@
-#! /home/nikolaj/.pyenv/shims/python
+#! /usr/bin/env python
 """
 Usage:
-    cent (-h|--help)
-    cent -i FILE
-    cent -c [--keep-c] FILE
+  cent (-h|--help)
+  cent -i FILE
+  cent -c [-k|--keep-c] FILE
 
 Options:
-    -h --help   Print this help screen
-    -i          Run the interpreter
-    -c          Run the compiler
-    --keep-c    Keep the generated C file alongside the binary
-    FILE        The file to compile/interpret
+  -h --help     Print this help screen
+  -i            Run the interpreter
+  -c            Run the compiler
+  -k --keep-c   Keep the generated C file alongside the binary
+  FILE          The file to compile/interpret
 """
 import os
 import subprocess
@@ -27,56 +27,56 @@ from centvrion.ast_nodes import Program
 from centvrion.compiler.emitter import compile_program
 
 def main():
-    args = docopt(__doc__)
-    file_path = args["FILE"]
-    with open(file_path, "r", encoding="utf-8") as file_pointer:
-        program_text = file_pointer.read() + "\n"
+  args = docopt(__doc__)
+  file_path = args["FILE"]
+  with open(file_path, "r", encoding="utf-8") as file_pointer:
+    program_text = file_pointer.read() + "\n"
 
-    lexer = Lexer().get_lexer()
-    parser = Parser()
+  lexer = Lexer().get_lexer()
+  parser = Parser()
 
-    try:
-        tokens = lexer.lex(program_text)
-        program = parser.parse(tokens)
-    except LexingError as e:
-        pos = e.source_pos
-        char = program_text[pos.idx] if pos.idx < len(program_text) else "?"
-        sys.exit(f"CENTVRION error: Invalid character {char!r} at line {pos.lineno}, column {pos.colno}")
+  try:
+    tokens = lexer.lex(program_text)
+    program = parser.parse(tokens)
+  except LexingError as e:
+    pos = e.source_pos
+    char = program_text[pos.idx] if pos.idx < len(program_text) else "?"
+    sys.exit(f"CENTVRION error: Invalid character {char!r} at line {pos.lineno}, column {pos.colno}")
 
-    if isinstance(program, Program):
-        if args["-i"]:
-            try:
-                program.eval()
-            except CentvrionError as e:
-                sys.exit(f"CENTVRION error: {e}")
-        else:
-            c_source = compile_program(program)
-            runtime_c = os.path.join(
-                os.path.dirname(__file__),
-                "centvrion", "compiler", "runtime", "cent_runtime.c"
-            )
-            out_path = os.path.splitext(file_path)[0]
-            if args["--keep-c"]:
-                tmp_path = out_path + ".c"
-                with open(tmp_path, "w") as f:
-                    f.write(c_source)
-                subprocess.run(
-                    ["gcc", "-O2", tmp_path, runtime_c, "-o", out_path],
-                    check=True,
-                )
-            else:
-                with tempfile.NamedTemporaryFile(suffix=".c", delete=False, mode="w") as tmp:
-                    tmp.write(c_source)
-                    tmp_path = tmp.name
-                try:
-                    subprocess.run(
-                        ["gcc", "-O2", tmp_path, runtime_c, "-o", out_path],
-                        check=True,
-                    )
-                finally:
-                    os.unlink(tmp_path)
+  if isinstance(program, Program):
+    if args["-i"]:
+      try:
+        program.eval()
+      except CentvrionError as e:
+        sys.exit(f"CENTVRION error: {e}")
     else:
-        raise Exception("Output not of type 'Program'", type(program))
+      c_source = compile_program(program)
+      runtime_c = os.path.join(
+        os.path.dirname(__file__),
+        "centvrion", "compiler", "runtime", "cent_runtime.c"
+      )
+      out_path = os.path.splitext(file_path)[0]
+      if args["--keep-c"]:
+        tmp_path = out_path + ".c"
+        with open(tmp_path, "w") as f:
+          f.write(c_source)
+        subprocess.run(
+          ["gcc", "-O2", tmp_path, runtime_c, "-o", out_path],
+          check=True,
+        )
+      else:
+        with tempfile.NamedTemporaryFile(suffix=".c", delete=False, mode="w") as tmp:
+          tmp.write(c_source)
+          tmp_path = tmp.name
+        try:
+          subprocess.run(
+            ["gcc", "-O2", tmp_path, runtime_c, "-o", out_path],
+            check=True,
+          )
+        finally:
+          os.unlink(tmp_path)
+  else:
+    raise Exception("Output not of type 'Program'", type(program))
 
 if __name__ == "__main__":
-    main()
+  main()

centvrion/ast_nodes.py

@@ -169,7 +169,7 @@ def frac_to_fraction(s, magnvm=False, svbnvlla=False):
 def fraction_to_frac(f, magnvm=False, svbnvlla=False):
   if f < 0:
     if not svbnvlla:
-      raise CentvrionError("Cannot display negative fractions without 'SVBNVLLA' module")
+      raise CentvrionError("Cannot display negative numbers without 'SVBNVLLA' module")
     return "-" + fraction_to_frac(-f, magnvm, svbnvlla)
 
   integer_part = int(f)
@@ -899,6 +899,9 @@ class BuiltIn(Node):
         if not isinstance(params[0], ValList):
           raise CentvrionError("LONGITVDO requires an array")
         return vtable, ValInt(len(params[0].value()))
+      case "EVERRO":
+        print("\033[2J\033[H", end="", flush=True)
+        return vtable, ValNul()
       case _:
         raise NotImplementedError(self.builtin)
 

centvrion/compiler/emit_expr.py

@@ -187,6 +187,10 @@ def _emit_builtin(node, ctx):
       lines.append("break;")
       lines.append(f"CentValue {tmp} = cent_null();")
 
+    case "EVERRO":
+      lines.append("cent_everro();")
+      lines.append(f"CentValue {tmp} = cent_null();")
+
     case _:
       raise NotImplementedError(node.builtin)
 

centvrion/compiler/runtime/cent_runtime.c

@@ -236,7 +236,7 @@ static int write_val(CentValue v, char *buf, int bufsz) {
       long num = v.fval.num, den = v.fval.den;
       if (den < 0) { num = -num; den = -den; }
       if (num < 0)
-        cent_runtime_error("cannot display negative fraction without SVBNVLLA");
+        cent_runtime_error("cannot display negative numbers without SVBNVLLA");
       long int_part = num / den;
       long rem_num  = num % den;
 
@@ -458,6 +458,11 @@ void cent_dice(CentValue v) {
   fputc('\n', stdout);
 }
 
+void cent_everro(void) {
+  fputs("\033[2J\033[H", stdout);
+  fflush(stdout);
+}
+
 CentValue cent_avdi(void) {
   char *buf = cent_arena_alloc(cent_arena, 1024);
   if (!fgets(buf, 1024, stdin)) {

centvrion/compiler/runtime/cent_runtime.h

@@ -174,6 +174,7 @@ CentValue cent_avdi_numerus(void);                    /* AVDI_NVMERVS */
 CentValue cent_longitudo(CentValue v);                  /* LONGITVDO  */
 CentValue cent_fortis_numerus(CentValue lo, CentValue hi); /* FORTIS_NVMERVS */
 CentValue cent_fortis_electionis(CentValue lst);          /* FORTIS_ELECTIONIS */
+void      cent_everro(void);                                   /* EVERRO */
 
 /* ------------------------------------------------------------------ */
 /* Array helpers                                                        */

centvrion/lexer.py

@@ -35,6 +35,7 @@ builtin_tokens = [("BUILTIN", i) for i in [
   "AVDI_NVMERVS",
   "AVDI",
   "DICE",
+  "EVERRO",
   "FORTIS_NVMERVS",
   "FORTIS_ELECTIONIS",
   "LONGITVDO"

examples/connect_iv.cent

@@ -0,0 +1,282 @@
+// Connect IV — Play against a perfect AI
+// Minimax with alpha-beta pruning + center-first move ordering
+// You are X (player I), AI is O (player II)
+// Enter column as Roman numeral I-VII
+
+// Returns the bottommost empty row in col, or NVLLVS if full
+DEFINI find_slot(b, col) VT {
+  DESIGNA ans VT NVLLVS
+  DONICVM r VT I VSQVE VII FACE {
+    SI b[(r - I) * VII + col] EST NVLLVS TVNC {
+      DESIGNA ans VT r
+    }
+  }
+  REDI(ans)
+}
+
+// Returns VERITAS if player has four in a row
+DEFINI est_victor(b, player) VT {
+  DONICVM r VT I VSQVE VII FACE {
+    DONICVM c VT I VSQVE V FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      SI b[idx] EST player ET b[idx + I] EST player ET b[idx + II] EST player ET b[idx + III] EST player TVNC {
+        REDI(VERITAS)
+      }
+    }
+  }
+  DONICVM r VT I VSQVE IV FACE {
+    DONICVM c VT I VSQVE VIII FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      SI b[idx] EST player ET b[idx + VII] EST player ET b[idx + XIV] EST player ET b[idx + XXI] EST player TVNC {
+        REDI(VERITAS)
+      }
+    }
+  }
+  DONICVM r VT I VSQVE IV FACE {
+    DONICVM c VT I VSQVE V FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      SI b[idx] EST player ET b[idx + VIII] EST player ET b[idx + XVI] EST player ET b[idx + XXIV] EST player TVNC {
+        REDI(VERITAS)
+      }
+    }
+  }
+  DONICVM r VT I VSQVE IV FACE {
+    DONICVM c VT IV VSQVE VIII FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      SI b[idx] EST player ET b[idx + VI] EST player ET b[idx + XII] EST player ET b[idx + XVIII] EST player TVNC {
+        REDI(VERITAS)
+      }
+    }
+  }
+  REDI(FALSITAS)
+}
+
+DEFINI print_board(b) VT {
+  DICE("+---+---+---+---+---+---+---+")
+  DONICVM r VT I VSQVE VII FACE {
+    DESIGNA line VT "| "
+    DONICVM c VT I VSQVE VIII FACE {
+      DESIGNA cell VT b[(r - I) * VII + c]
+      SI cell EST I TVNC {
+        DESIGNA line VT line & "X | "
+      } ALVID SI cell EST II TVNC {
+        DESIGNA line VT line & "O | "
+      } ALVID {
+        DESIGNA line VT line & ". | "
+      }
+    }
+    DICE(line)
+  }
+  DICE("+---+---+---+---+---+---+---+")
+  DICE("  I   II III IV   V   VI VII")
+  REDI(NVLLVS)
+}
+
+// Score a 4-cell window: positive favours AI (II), negative favours player (I).
+// Only scores windows that are not mixed (one side can still win them).
+DEFINI score_fenestram(a, b, c, d) VT {
+  DESIGNA ai VT NVLLVS
+  DESIGNA pl VT NVLLVS
+  SI a EST II TVNC { DESIGNA ai VT ai + I }
+  SI b EST II TVNC { DESIGNA ai VT ai + I }
+  SI c EST II TVNC { DESIGNA ai VT ai + I }
+  SI d EST II TVNC { DESIGNA ai VT ai + I }
+  SI a EST I TVNC { DESIGNA pl VT pl + I }
+  SI b EST I TVNC { DESIGNA pl VT pl + I }
+  SI c EST I TVNC { DESIGNA pl VT pl + I }
+  SI d EST I TVNC { DESIGNA pl VT pl + I }
+  SI pl EST NVLLVS TVNC {
+    SI ai EST III TVNC { REDI(V) }
+    SI ai EST II TVNC { REDI(II) }
+  }
+  SI ai EST NVLLVS TVNC {
+    SI pl EST III TVNC { REDI(NVLLVS - V) }
+    SI pl EST II TVNC { REDI(NVLLVS - II) }
+  }
+  REDI(NVLLVS)
+}
+
+// Static board evaluation: scan all 69 windows of 4 cells.
+// Returns a score in roughly [-350, 350]; positive = AI advantage.
+DEFINI aestima(b) VT {
+  DESIGNA score VT NVLLVS
+  // Center column preference: each AI piece in column IV is worth +1
+  DONICVM r VT I VSQVE VII FACE {
+    SI b[(r - I) * VII + IV] EST II TVNC {
+      DESIGNA score VT score + I
+    }
+  }
+  // Horizontal windows (6 rows x 4 starting columns = 24)
+  DONICVM r VT I VSQVE VII FACE {
+    DONICVM c VT I VSQVE V FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      DESIGNA score VT score + INVOCA score_fenestram(b[idx], b[idx + I], b[idx + II], b[idx + III])
+    }
+  }
+  // Vertical windows (3 starting rows x 7 columns = 21)
+  DONICVM r VT I VSQVE IV FACE {
+    DONICVM c VT I VSQVE VIII FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      DESIGNA score VT score + INVOCA score_fenestram(b[idx], b[idx + VII], b[idx + XIV], b[idx + XXI])
+    }
+  }
+  // Diagonal up-right windows (3 starting rows x 4 starting columns = 12)
+  DONICVM r VT I VSQVE IV FACE {
+    DONICVM c VT I VSQVE V FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      DESIGNA score VT score + INVOCA score_fenestram(b[idx], b[idx + VIII], b[idx + XVI], b[idx + XXIV])
+    }
+  }
+  // Diagonal up-left windows (3 starting rows x 4 starting columns = 12)
+  DONICVM r VT I VSQVE IV FACE {
+    DONICVM c VT IV VSQVE VIII FACE {
+      DESIGNA idx VT (r - I) * VII + c
+      DESIGNA score VT score + INVOCA score_fenestram(b[idx], b[idx + VI], b[idx + XII], b[idx + XVIII])
+    }
+  }
+  REDI(score)
+}
+
+// Minimax with alpha-beta pruning and depth-limited aestima evaluation.
+// depth = remaining search plies (counts down from a fixed budget).
+// Wins score ±(M + depth) so the search always prefers quicker wins and
+// delays losses; aestima values stay well within ±M so wins dominate.
+DEFINI minimax(b, depth, alpha, beta, maxi) VT {
+  SI maxi TVNC {
+    SI INVOCA est_victor(b, I) TVNC {
+      REDI(NVLLVS - M - depth)
+    }
+  } ALVID {
+    SI INVOCA est_victor(b, II) TVNC {
+      REDI(M + depth)
+    }
+  }
+  SI depth EST I TVNC {
+    REDI(INVOCA aestima(b))
+  }
+  DESIGNA col_order VT [IV, III, V, II, VI, I, VII]
+  SI maxi TVNC {
+    DESIGNA best VT NVLLVS - M - VII
+    PER c IN col_order FACE {
+      DESIGNA linea VT INVOCA find_slot(b, c)
+      SI NON (linea EST NVLLVS) TVNC {
+        DESIGNA b[(linea - I) * VII + c] VT II
+        DESIGNA score VT INVOCA minimax(b, depth - I, alpha, beta, FALSITAS)
+        DESIGNA b[(linea - I) * VII + c] VT NVLLVS
+        SI score PLVS best TVNC {
+          DESIGNA best VT score
+        }
+        SI best PLVS alpha TVNC {
+          DESIGNA alpha VT best
+        }
+        SI beta MINVS alpha AVT beta EST alpha TVNC {
+          ERVMPE
+        }
+      }
+    }
+    REDI(best)
+  } ALVID {
+    DESIGNA best VT M + VII
+    PER c IN col_order FACE {
+      DESIGNA linea VT INVOCA find_slot(b, c)
+      SI NON (linea EST NVLLVS) TVNC {
+        DESIGNA b[(linea - I) * VII + c] VT I
+        DESIGNA score VT INVOCA minimax(b, depth - I, alpha, beta, VERITAS)
+        DESIGNA b[(linea - I) * VII + c] VT NVLLVS
+        SI score MINVS best TVNC {
+          DESIGNA best VT score
+        }
+        SI best MINVS beta TVNC {
+          DESIGNA beta VT best
+        }
+        SI beta MINVS alpha AVT beta EST alpha TVNC {
+          ERVMPE
+        }
+      }
+    }
+    REDI(best)
+  }
+}
+
+// Pick the best column for the AI (depth VI = 5 plies of lookahead)
+DEFINI ai_move(b) VT {
+  DESIGNA col_order VT [IV, III, V, II, VI, I, VII]
+  DESIGNA best_score VT NVLLVS - M - VII
+  DESIGNA best_col VT IV
+  PER c IN col_order FACE {
+    DESIGNA linea VT INVOCA find_slot(b, c)
+    SI NON (linea EST NVLLVS) TVNC {
+      DESIGNA b[(linea - I) * VII + c] VT II
+      DESIGNA score VT INVOCA minimax(b, VI, NVLLVS - M - VII, M + VII, FALSITAS)
+      DESIGNA b[(linea - I) * VII + c] VT NVLLVS
+      SI score PLVS best_score TVNC {
+        DESIGNA best_score VT score
+        DESIGNA best_col VT c
+      }
+    }
+  }
+  REDI(best_col)
+}
+
+// --- Board setup ---
+DESIGNA board VT [I VSQVE XLIII]
+DONICVM i VT I VSQVE XLIII FACE {
+  DESIGNA board[i] VT NVLLVS
+}
+
+DESIGNA moves VT NVLLVS
+DESIGNA game_over VT FALSITAS
+
+DICE("=== CONNECT IV ===")
+DICE("You are X. AI is O.")
+DICE("Enter column as Roman numeral (I-VII).")
+DICE("")
+
+DVM game_over FACE {
+  EVERRO()
+  INVOCA print_board(board)
+
+  DICE("Your move:")
+  DESIGNA col VT AVDI_NVMERVS()
+  SI col PLVS VII TVNC {
+    DICE("Invalid column! Enter I through VII.")
+    CONTINVA
+  }
+  DESIGNA linea VT INVOCA find_slot(board, col)
+  SI linea EST NVLLVS TVNC {
+    DICE("Column full! Try another.")
+    CONTINVA
+  }
+  DESIGNA board[(linea - I) * VII + col] VT I
+  DESIGNA moves VT moves + I
+  SI INVOCA est_victor(board, I) TVNC {
+    INVOCA print_board(board)
+    DICE("You win!")
+    DESIGNA game_over VT VERITAS
+    CONTINVA
+  }
+  SI moves EST XLII TVNC {
+    INVOCA print_board(board)
+    DICE("Draw!")
+    DESIGNA game_over VT VERITAS
+    CONTINVA
+  }
+
+  DICE("AI is thinking...")
+  DESIGNA col VT INVOCA ai_move(board)
+  DESIGNA linea VT INVOCA find_slot(board, col)
+  DICE("AI plays column " & col & ".")
+  DESIGNA board[(linea - I) * VII + col] VT II
+  DESIGNA moves VT moves + I
+  SI INVOCA est_victor(board, II) TVNC {
+    INVOCA print_board(board)
+    DICE("AI wins!")
+    DESIGNA game_over VT VERITAS
+    CONTINVA
+  }
+  SI moves EST XLII TVNC {
+    INVOCA print_board(board)
+    DICE("Draw!")
+    DESIGNA game_over VT VERITAS
+  }
+}

tests.py

@@ -117,6 +117,7 @@ output_tests = [
   ("DICE(\"a\", \"b\")", Program([], [ExpressionStatement(BuiltIn("DICE", [String("a"), String("b")]))]), ValStr("a b"), "a b\n"),
   ("DICE(\"line one\")\nDICE(\"line two\")", Program([], [ExpressionStatement(BuiltIn("DICE", [String("line one")])), ExpressionStatement(BuiltIn("DICE", [String("line two")]))]), ValStr("line two"), "line one\nline two\n"),
   ("DICE(DICE(II))", Program([], [ExpressionStatement(BuiltIn("DICE", [BuiltIn("DICE", [Numeral("II")])]))]), ValStr("II"), "II\nII\n"),
+  ("EVERRO()", Program([], [ExpressionStatement(BuiltIn("EVERRO", []))]), ValNul(), "\033[2J\033[H"),
 ]
 
 class TestOutput(unittest.TestCase):