diff --git a/package-lock.json b/package-lock.json
index 7da192880..0b5c6c194 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -19,7 +19,9 @@
       },
       "devDependencies": {
         "@types/node": "^18.7.15",
-        "@types/yargs": "^17.0.12"
+        "@types/yargs": "^17.0.12",
+        "commonmark": "^0.30.0",
+        "glob": "^8.0.3"
       }
     },
     "node_modules/@types/node": {
@@ -65,6 +67,21 @@
         "url": "https://github.com/chalk/ansi-styles?sponsor=1"
       }
     },
+    "node_modules/balanced-match": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz",
+      "integrity": "sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==",
+      "dev": true
+    },
+    "node_modules/brace-expansion": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.1.tgz",
+      "integrity": "sha512-XnAIvQ8eM+kC6aULx6wuQiwVsnzsi9d3WxzV3FpWTGA19F621kwdbsAcFKXgKUHZWsy+mY6iL1sHTxWEFCytDA==",
+      "dev": true,
+      "dependencies": {
+        "balanced-match": "^1.0.0"
+      }
+    },
     "node_modules/buffer-from": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/buffer-from/-/buffer-from-1.1.2.tgz",
@@ -96,11 +113,35 @@
       "resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
       "integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA=="
     },
+    "node_modules/commonmark": {
+      "version": "0.30.0",
+      "resolved": "https://registry.npmjs.org/commonmark/-/commonmark-0.30.0.tgz",
+      "integrity": "sha512-j1yoUo4gxPND1JWV9xj5ELih0yMv1iCWDG6eEQIPLSWLxzCXiFoyS7kvB+WwU+tZMf4snwJMMtaubV0laFpiBA==",
+      "dev": true,
+      "dependencies": {
+        "entities": "~2.0",
+        "mdurl": "~1.0.1",
+        "minimist": ">=1.2.2",
+        "string.prototype.repeat": "^0.2.0"
+      },
+      "bin": {
+        "commonmark": "bin/commonmark"
+      },
+      "engines": {
+        "node": "*"
+      }
+    },
     "node_modules/emoji-regex": {
       "version": "8.0.0",
       "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-8.0.0.tgz",
       "integrity": "sha512-MSjYzcWNOA0ewAHpz0MxpYFvwg6yjy1NG3xteoqz644VCo/RPgnr1/GGt+ic3iJTzQ8Eu3TdM14SawnVUmGE6A=="
     },
+    "node_modules/entities": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/entities/-/entities-2.0.3.tgz",
+      "integrity": "sha512-MyoZ0jgnLvB2X3Lg5HqpFmn1kybDiIfEQmKzTb5apr51Rb+T3KdmMiqa70T+bhGnyv7bQ6WMj2QMHpGMmlrUYQ==",
+      "dev": true
+    },
     "node_modules/escalade": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.1.1.tgz",
@@ -109,6 +150,12 @@
         "node": ">=6"
       }
     },
+    "node_modules/fs.realpath": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
+      "integrity": "sha512-OO0pH2lK6a0hZnAdau5ItzHPI6pUlvI7jMVnxUQRtw4owF2wk8lOSabtGDCTP4Ggrg2MbGnWO9X8K1t4+fGMDw==",
+      "dev": true
+    },
     "node_modules/get-caller-file": {
       "version": "2.0.5",
       "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-2.0.5.tgz",
@@ -117,6 +164,41 @@
         "node": "6.* || 8.* || >= 10.*"
       }
     },
+    "node_modules/glob": {
+      "version": "8.0.3",
+      "resolved": "https://registry.npmjs.org/glob/-/glob-8.0.3.tgz",
+      "integrity": "sha512-ull455NHSHI/Y1FqGaaYFaLGkNMMJbavMrEGFXG/PGrg6y7sutWHUHrz6gy6WEBH6akM1M414dWKCNs+IhKdiQ==",
+      "dev": true,
+      "dependencies": {
+        "fs.realpath": "^1.0.0",
+        "inflight": "^1.0.4",
+        "inherits": "2",
+        "minimatch": "^5.0.1",
+        "once": "^1.3.0"
+      },
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/isaacs"
+      }
+    },
+    "node_modules/inflight": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/inflight/-/inflight-1.0.6.tgz",
+      "integrity": "sha512-k92I/b08q4wvFscXCLvqfsHCrjrF7yiXsQuIVvVE7N82W3+aqpzuUdBbfhWcy/FZR3/4IgflMgKLOsvPDrGCJA==",
+      "dev": true,
+      "dependencies": {
+        "once": "^1.3.0",
+        "wrappy": "1"
+      }
+    },
+    "node_modules/inherits": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "dev": true
+    },
     "node_modules/is-fullwidth-code-point": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/is-fullwidth-code-point/-/is-fullwidth-code-point-3.0.0.tgz",
@@ -125,6 +207,39 @@
         "node": ">=8"
       }
     },
+    "node_modules/mdurl": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/mdurl/-/mdurl-1.0.1.tgz",
+      "integrity": "sha512-/sKlQJCBYVY9Ers9hqzKou4H6V5UWc/M59TH2dvkt+84itfnq7uFOMLpOiOS4ujvHP4etln18fmIxA5R5fll0g==",
+      "dev": true
+    },
+    "node_modules/minimatch": {
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-5.1.0.tgz",
+      "integrity": "sha512-9TPBGGak4nHfGZsPBohm9AWg6NoT7QTCehS3BIJABslyZbzxfV78QM2Y6+i741OPZIafFAaiiEMh5OyIrJPgtg==",
+      "dev": true,
+      "dependencies": {
+        "brace-expansion": "^2.0.1"
+      },
+      "engines": {
+        "node": ">=10"
+      }
+    },
+    "node_modules/minimist": {
+      "version": "1.2.6",
+      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.6.tgz",
+      "integrity": "sha512-Jsjnk4bw3YJqYzbdyBiNsPWHPfO++UGG749Cxs6peCu5Xg4nrena6OVxOYxrQTqww0Jmwt+Ref8rggumkTLz9Q==",
+      "dev": true
+    },
+    "node_modules/once": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
+      "integrity": "sha512-lNaJgI+2Q5URQBkccEKHTQOPaXdUxnZZElQTZY0MFUAuaEqe1E+Nyvgdz/aIyNi6Z9MzO5dv1H8n58/GELp3+w==",
+      "dev": true,
+      "dependencies": {
+        "wrappy": "1"
+      }
+    },
     "node_modules/require-directory": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/require-directory/-/require-directory-2.1.1.tgz",
@@ -163,6 +278,12 @@
         "node": ">=8"
       }
     },
+    "node_modules/string.prototype.repeat": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/string.prototype.repeat/-/string.prototype.repeat-0.2.0.tgz",
+      "integrity": "sha512-1BH+X+1hSthZFW+X+JaUkjkkUPwIlLEMJBLANN3hOob3RhEk5snLWNECDnYbgn/m5c5JV7Ersu1Yubaf+05cIA==",
+      "dev": true
+    },
     "node_modules/strip-ansi": {
       "version": "6.0.1",
       "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-6.0.1.tgz",
@@ -195,6 +316,12 @@
         "url": "https://github.com/chalk/wrap-ansi?sponsor=1"
       }
     },
+    "node_modules/wrappy": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
+      "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
+      "dev": true
+    },
     "node_modules/y18n": {
       "version": "5.0.8",
       "resolved": "https://registry.npmjs.org/y18n/-/y18n-5.0.8.tgz",
@@ -269,6 +396,21 @@
         "color-convert": "^2.0.1"
       }
     },
+    "balanced-match": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz",
+      "integrity": "sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==",
+      "dev": true
+    },
+    "brace-expansion": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.1.tgz",
+      "integrity": "sha512-XnAIvQ8eM+kC6aULx6wuQiwVsnzsi9d3WxzV3FpWTGA19F621kwdbsAcFKXgKUHZWsy+mY6iL1sHTxWEFCytDA==",
+      "dev": true,
+      "requires": {
+        "balanced-match": "^1.0.0"
+      }
+    },
     "buffer-from": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/buffer-from/-/buffer-from-1.1.2.tgz",
@@ -297,26 +439,109 @@
       "resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
       "integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA=="
     },
+    "commonmark": {
+      "version": "0.30.0",
+      "resolved": "https://registry.npmjs.org/commonmark/-/commonmark-0.30.0.tgz",
+      "integrity": "sha512-j1yoUo4gxPND1JWV9xj5ELih0yMv1iCWDG6eEQIPLSWLxzCXiFoyS7kvB+WwU+tZMf4snwJMMtaubV0laFpiBA==",
+      "dev": true,
+      "requires": {
+        "entities": "~2.0",
+        "mdurl": "~1.0.1",
+        "minimist": ">=1.2.2",
+        "string.prototype.repeat": "^0.2.0"
+      }
+    },
     "emoji-regex": {
       "version": "8.0.0",
       "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-8.0.0.tgz",
       "integrity": "sha512-MSjYzcWNOA0ewAHpz0MxpYFvwg6yjy1NG3xteoqz644VCo/RPgnr1/GGt+ic3iJTzQ8Eu3TdM14SawnVUmGE6A=="
     },
+    "entities": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/entities/-/entities-2.0.3.tgz",
+      "integrity": "sha512-MyoZ0jgnLvB2X3Lg5HqpFmn1kybDiIfEQmKzTb5apr51Rb+T3KdmMiqa70T+bhGnyv7bQ6WMj2QMHpGMmlrUYQ==",
+      "dev": true
+    },
     "escalade": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/escalade/-/escalade-3.1.1.tgz",
       "integrity": "sha512-k0er2gUkLf8O0zKJiAhmkTnJlTvINGv7ygDNPbeIsX/TJjGJZHuh9B2UxbsaEkmlEo9MfhrSzmhIlhRlI2GXnw=="
     },
+    "fs.realpath": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
+      "integrity": "sha512-OO0pH2lK6a0hZnAdau5ItzHPI6pUlvI7jMVnxUQRtw4owF2wk8lOSabtGDCTP4Ggrg2MbGnWO9X8K1t4+fGMDw==",
+      "dev": true
+    },
     "get-caller-file": {
       "version": "2.0.5",
       "resolved": "https://registry.npmjs.org/get-caller-file/-/get-caller-file-2.0.5.tgz",
       "integrity": "sha512-DyFP3BM/3YHTQOCUL/w0OZHR0lpKeGrxotcHWcqNEdnltqFwXVfhEBQ94eIo34AfQpo0rGki4cyIiftY06h2Fg=="
     },
+    "glob": {
+      "version": "8.0.3",
+      "resolved": "https://registry.npmjs.org/glob/-/glob-8.0.3.tgz",
+      "integrity": "sha512-ull455NHSHI/Y1FqGaaYFaLGkNMMJbavMrEGFXG/PGrg6y7sutWHUHrz6gy6WEBH6akM1M414dWKCNs+IhKdiQ==",
+      "dev": true,
+      "requires": {
+        "fs.realpath": "^1.0.0",
+        "inflight": "^1.0.4",
+        "inherits": "2",
+        "minimatch": "^5.0.1",
+        "once": "^1.3.0"
+      }
+    },
+    "inflight": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/inflight/-/inflight-1.0.6.tgz",
+      "integrity": "sha512-k92I/b08q4wvFscXCLvqfsHCrjrF7yiXsQuIVvVE7N82W3+aqpzuUdBbfhWcy/FZR3/4IgflMgKLOsvPDrGCJA==",
+      "dev": true,
+      "requires": {
+        "once": "^1.3.0",
+        "wrappy": "1"
+      }
+    },
+    "inherits": {
+      "version": "2.0.4",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
+      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
+      "dev": true
+    },
     "is-fullwidth-code-point": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/is-fullwidth-code-point/-/is-fullwidth-code-point-3.0.0.tgz",
       "integrity": "sha512-zymm5+u+sCsSWyD9qNaejV3DFvhCKclKdizYaJUuHA83RLjb7nSuGnddCHGv0hk+KY7BMAlsWeK4Ueg6EV6XQg=="
     },
+    "mdurl": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/mdurl/-/mdurl-1.0.1.tgz",
+      "integrity": "sha512-/sKlQJCBYVY9Ers9hqzKou4H6V5UWc/M59TH2dvkt+84itfnq7uFOMLpOiOS4ujvHP4etln18fmIxA5R5fll0g==",
+      "dev": true
+    },
+    "minimatch": {
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-5.1.0.tgz",
+      "integrity": "sha512-9TPBGGak4nHfGZsPBohm9AWg6NoT7QTCehS3BIJABslyZbzxfV78QM2Y6+i741OPZIafFAaiiEMh5OyIrJPgtg==",
+      "dev": true,
+      "requires": {
+        "brace-expansion": "^2.0.1"
+      }
+    },
+    "minimist": {
+      "version": "1.2.6",
+      "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.6.tgz",
+      "integrity": "sha512-Jsjnk4bw3YJqYzbdyBiNsPWHPfO++UGG749Cxs6peCu5Xg4nrena6OVxOYxrQTqww0Jmwt+Ref8rggumkTLz9Q==",
+      "dev": true
+    },
+    "once": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
+      "integrity": "sha512-lNaJgI+2Q5URQBkccEKHTQOPaXdUxnZZElQTZY0MFUAuaEqe1E+Nyvgdz/aIyNi6Z9MzO5dv1H8n58/GELp3+w==",
+      "dev": true,
+      "requires": {
+        "wrappy": "1"
+      }
+    },
     "require-directory": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/require-directory/-/require-directory-2.1.1.tgz",
@@ -346,6 +571,12 @@
         "strip-ansi": "^6.0.1"
       }
     },
+    "string.prototype.repeat": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/string.prototype.repeat/-/string.prototype.repeat-0.2.0.tgz",
+      "integrity": "sha512-1BH+X+1hSthZFW+X+JaUkjkkUPwIlLEMJBLANN3hOob3RhEk5snLWNECDnYbgn/m5c5JV7Ersu1Yubaf+05cIA==",
+      "dev": true
+    },
     "strip-ansi": {
       "version": "6.0.1",
       "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-6.0.1.tgz",
@@ -369,6 +600,12 @@
         "strip-ansi": "^6.0.0"
       }
     },
+    "wrappy": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
+      "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
+      "dev": true
+    },
     "y18n": {
       "version": "5.0.8",
       "resolved": "https://registry.npmjs.org/y18n/-/y18n-5.0.8.tgz",
diff --git a/package.json b/package.json
index f3f6a06a6..47e740543 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,7 @@
     "bolt": "lib/bin/bolt.js"
   },
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "node ./lib/bin/bolt-selftest.js run"
   },
   "repository": {
     "type": "git",
@@ -29,6 +29,8 @@
   },
   "devDependencies": {
     "@types/node": "^18.7.15",
-    "@types/yargs": "^17.0.12"
+    "@types/yargs": "^17.0.12",
+    "commonmark": "^0.30.0",
+    "glob": "^8.0.3"
   }
 }
diff --git a/src/bin/bolt-selftest.ts b/src/bin/bolt-selftest.ts
new file mode 100644
index 000000000..b93e94720
--- /dev/null
+++ b/src/bin/bolt-selftest.ts
@@ -0,0 +1,52 @@
+#!/usr/bin/env node
+
+import * as commonmark from "commonmark"
+import { sync as globSync } from "glob"
+import fs from "fs";
+import path from "path";
+import yargs from "yargs";
+import { Checker } from "../checker";
+import { TextFile } from "../cst";
+import { Parser } from "../parser";
+import { Punctuator, Scanner } from "../scanner";
+import { ConsoleDiagnostics, DiagnosticStore } from "../diagnostics";
+import { parseSourceFile } from "..";
+
+const projectDir = path.resolve(__dirname, '..', '..');
+
+interface Test {
+  code: string;
+}
+
+yargs
+  .command('run', 'Execute the current working tree and optionally save to disk', yargs => {}, async (args) => {
+    for await (const test of loadTests()) {
+      console.log('--------');
+      console.log(test.code);
+      const diagnostics = new ConsoleDiagnostics();
+      const file = new TextFile("#<anonymous>", test.code);
+      let sourceFile = parseSourceFile(file, diagnostics);
+      if (sourceFile !== null) {
+        sourceFile.setParents();
+        const checker = new Checker(diagnostics);
+        checker.check(sourceFile);
+      }
+    }
+  })
+  .argv;
+
+async function* loadTests(): AsyncIterable<Test> {
+  for (const filename of globSync(path.join(projectDir, 'src', 'test', '**', '*.md'))) {
+    const text = await fs.promises.readFile(filename, 'utf-8');
+    const reader = commonmark.Parser();
+    const root = reader.parse(text);
+    let child = root.firstChild;
+    while (child !== null) {
+      if (child.type === 'code_block') {
+        yield { code: child.literal };
+      }
+      child = child.next;
+    }
+  }
+}
+
diff --git a/src/bin/bolt.ts b/src/bin/bolt.ts
index 3b9c02e7f..4175d24d3 100644
--- a/src/bin/bolt.ts
+++ b/src/bin/bolt.ts
@@ -7,11 +7,12 @@ import path from "path"
 import fs from "fs"
 import yargs from "yargs"
 
-import { Diagnostics, UnexpectedCharDiagnostic, UnexpectedTokenDiagnostic } from "../diagnostics"
+import { ConsoleDiagnostics, Diagnostics, UnexpectedCharDiagnostic, UnexpectedTokenDiagnostic } from "../diagnostics"
 import { Punctuator, ScanError, Scanner } from "../scanner"
 import { ParseError, Parser } from "../parser"
 import { Checker } from "../checker"
 import { TextFile } from "../cst"
+import { parseSourceFile } from ".."
 
 function debug(value: any) {
   console.error(util.inspect(value, { colors: true, depth: Infinity }));
@@ -34,27 +35,13 @@ yargs
       const cwd = args.C;
       const filename = path.resolve(cwd, args.file);
 
-      const diagnostics = new Diagnostics();
+      const diagnostics = new ConsoleDiagnostics();
       const text = fs.readFileSync(filename, 'utf8')
       const file = new TextFile(filename, text);
-      const scanner = new Scanner(text, 0, diagnostics, file);
-      const punctuated = new Punctuator(scanner);
-      const parser = new Parser(file, punctuated);
-      let sourceFile;
-      try {
-        sourceFile = parser.parseSourceFile();
-      } catch (error) {
-        if (error instanceof ParseError) {
-          diagnostics.add(new UnexpectedTokenDiagnostic(error.file, error.actual, error.expected));
-          return;
-        }
-        if (error instanceof ScanError) {
-          diagnostics.add(new UnexpectedCharDiagnostic(error.file, error.position, error.actual));
-          return;
-        }
-        throw error;
+      const sourceFile = parseSourceFile(file, diagnostics);
+      if (sourceFile === null) {
+        process.exit(1);
       }
-      sourceFile.setParents();
       //debug(sourceFile.toJSON());
       const checker = new Checker(diagnostics);
       checker.check(sourceFile);
diff --git a/src/diagnostics.ts b/src/diagnostics.ts
index 4bde0bdee..b07548cdc 100644
--- a/src/diagnostics.ts
+++ b/src/diagnostics.ts
@@ -26,8 +26,19 @@ const ANSI_BG_CYAN = "\u001b[45m"
 const ANSI_BG_MAGENTA = "\u001b[46m"
 const ANSI_BG_WHITE = "\u001b[47m"
 
+const enum Level {
+  Debug,
+  Verbose,
+  Info,
+  Warning,
+  Error,
+  Fatal,
+}
+
 export class UnexpectedCharDiagnostic {
 
+  public readonly level = Level.Error;
+
   public constructor(
     public file: TextFile,
     public position: TextPosition,
@@ -111,6 +122,8 @@ function describeActual(token: Token): string {
 
 export class UnexpectedTokenDiagnostic {
 
+  public readonly level = Level.Error;
+
   public constructor(
     public file: TextFile,
     public actual: Token,
@@ -129,6 +142,8 @@ export class UnexpectedTokenDiagnostic {
 
 export class BindingNotFoudDiagnostic {
 
+  public readonly level = Level.Error;
+
   public constructor(
     public name: string,
     public node: Syntax,
@@ -202,6 +217,8 @@ export function describeType(type: Type): string {
 
 export class UnificationFailedDiagnostic {
 
+  public readonly level = Level.Error;
+
   public constructor(
     public left: Type,
     public right: Type,
@@ -230,6 +247,8 @@ export class UnificationFailedDiagnostic {
 
 export class ArityMismatchDiagnostic {
 
+  public readonly level = Level.Error;
+
   public constructor(
     public left: TArrow,
     public right: TArrow,
@@ -255,12 +274,36 @@ export type Diagnostic
   | UnexpectedTokenDiagnostic
   | ArityMismatchDiagnostic
 
-export class Diagnostics {
+export interface Diagnostics {
+  add(diagnostic: Diagnostic): void;
+}
 
-  private savedDiagnostics: Diagnostic[] = [];
+export class DiagnosticStore {
+
+  private storage: Diagnostic[] = [];
+  
+  public hasError = false;
+  public hasFatal = false;
+
+  public add(diagnostic: Diagnostic): void {
+    this.storage.push(diagnostic);
+    if (diagnostic.level >= Level.Error) {
+      this.hasError = true;
+    }
+    if (diagnostic.level >= Level.Fatal) {
+      this.hasFatal = true;
+    }
+  }
+
+  public getDiagnostics(): Iterable<Diagnostic> {
+    return this.storage;
+  }
+
+}
+
+export class ConsoleDiagnostics {
 
   public add(diagnostic: Diagnostic): void {
-    this.savedDiagnostics.push(diagnostic);
     process.stderr.write(diagnostic.format());
   }