PureScript MCP Server

Instructions

Implementation Reference

• index.js:887-921 (handler)

  Handler function that uses Tree-sitter to parse PureScript code, queries for 'where' clauses in functions (where keyword followed by declarations block), extracts and combines the text of these blocks, deduplicates them, and returns as a JSON array of strings.
  "getWhereBindings": async (args) => { if (!treeSitterInitialized) throw new Error("Tree-sitter not initialized."); const code = await getCodeFromInput(args, false); // Snippet-oriented const tree = purescriptTsParser.parse(code); const whereClausesText = []; // Query for 'where' keyword followed by a 'declarations' block within a function or let binding const querySource = ` (function (where) @where_keyword (declarations) @declarations_block) `; // Also consider 'let' bindings with 'where' clauses, though less common for top-level 'where' // (let_binding (where) @where_keyword (declarations) @declarations_block) const query = new Query(PureScriptLanguage, querySource); const matches = query.matches(tree.rootNode); for (const match of matches) { const whereKeywordNode = match.captures.find(c => c.name === 'where_keyword')?.node; const declarationsNode = match.captures.find(c => c.name === 'declarations_block')?.node; if (whereKeywordNode && declarationsNode) { // Construct the text from "where" keyword to the end of the declarations block // This requires careful handling of start and end positions if they are not contiguous in the source text string // For simplicity, if they are siblings and in order, we can take text from start of 'where' to end of 'declarations' // A safer way is to combine their individual texts if they represent the full conceptual block const fullWhereClauseText = `${whereKeywordNode.text} ${declarationsNode.text}`; whereClausesText.push(fullWhereClauseText.trim()); } } // Deduplicate, as some complex structures might yield multiple partial matches const uniqueWhereClauses = [...new Set(whereClausesText)]; return { content: [{ type: "text", text: JSON.stringify(uniqueWhereClauses, null, 2) }] }; },
• index.js:628-636 (registration)

  Tool registration in TOOL_DEFINITIONS array, including name, description, and input schema (requires 'code' string). Used by tools/list method.
  name: "getWhereBindings", description: "Find 'where' clauses in PureScript functions. These contain local helper functions and variables. Useful for understanding function implementation details.", inputSchema: { type: "object", properties: { code: { type: "string", description: "PureScript code snippet." } }, required: ["code"], additionalProperties: false } },
• index.js:628-636 (schema)

  Input schema definition for getWhereBindings tool: object with required 'code' property (PureScript code snippet).
  name: "getWhereBindings", description: "Find 'where' clauses in PureScript functions. These contain local helper functions and variables. Useful for understanding function implementation details.", inputSchema: { type: "object", properties: { code: { type: "string", description: "PureScript code snippet." } }, required: ["code"], additionalProperties: false } },
• index.js:125-151 (helper)

  Helper function getCodeFromInput used by getWhereBindings (and other tools) to retrieve code from args.code or filePath, validating inputs and preferring snippets for this tool.
  // Helper to get code from input args (filePath or code string) async function getCodeFromInput(args, isModuleOriented = true) { if (isModuleOriented) { const hasFilePath = args && typeof args.filePath === 'string'; const hasCode = args && typeof args.code === 'string'; if ((hasFilePath && hasCode) || (!hasFilePath && !hasCode)) { throw new Error("Invalid input: Exactly one of 'filePath' or 'code' must be provided for module-oriented tools."); } if (hasFilePath) { if (!path.isAbsolute(args.filePath)) { throw new Error(`Invalid filePath: '${args.filePath}' is not an absolute path. Only absolute paths are supported.`); } try { return await fs.readFile(args.filePath, 'utf-8'); } catch (e) { throw new Error(`Failed to read file at ${args.filePath}: ${e.message}`); } } return args.code; } else { // Snippet-oriented if (!args || typeof args.code !== 'string') { throw new Error("Invalid input: 'code' (string) is required for snippet-oriented tools."); } return args.code; } }