MCP-PIF Server

{-# LANGUAGE OverloadedStrings #-} {-| Module: Core.Encoder Description: RuntimeValue to JSON serialization and continuation detection Final pipeline stage that transforms RuntimeValues back to JSON for the MCP protocol. Provides two encoding functions: - runtimeToJson: Serializes evaluation results (RInt → Number, RClosure → "<function>") - termToJson: Serializes syntax trees for metaprogramming (enables code-as-data) The termToJson function maintains homoiconicity - Terms round-trip through JSON perfectly, enabling code introspection and manipulation. Key encoding choices: - Closures serialize as opaque "<function>" (use code_of for inspection) - Pairs serialize as {"pair": [a, b]} to distinguish from lists - Continuations include all resumption info (tool, input, step) Helper functions detect and extract continuations for the Server to handle recursive stepping at the MCP protocol level. -} module Core.Encoder ( runtimeToJson , termToJson , isContinuation , getContinuation ) where import Core.Types import Core.Syntax (Term(..)) import Data.Aeson import Data.Text (Text) import qualified Data.Vector as V {- JSON Serialization Serves Two Masters: 1. MCP Protocol (runtimeToJson): - Serialize evaluation results for protocol responses - Closures become opaque "<function>" - Continuations include resumption data 2. Metaprogramming (termToJson): - Serialize Terms for code-as-data introspection - Maintains homoiconicity - code can inspect code - Round-trips perfectly: JSON -> Term -> JSON This duality is why we have two functions rather than a type class. -} runtimeToJson :: RuntimeValue -> Value runtimeToJson (RInt n) = Number (fromIntegral n) runtimeToJson (RBool b) = Bool b runtimeToJson (RString s) = String s runtimeToJson (RList vs) = Array (V.fromList (map runtimeToJson vs)) runtimeToJson (RPair a b) = object [ "pair" .= [runtimeToJson a, runtimeToJson b] ] runtimeToJson (RClosure _ _ _) = String "<function>" runtimeToJson (RContinuation cont) = object [ "continuation" .= True , "tool" .= contToolName cont , "input" .= contInput cont , "step" .= contStepCount cont ] runtimeToJson (RQuoted term) = termToJson term runtimeToJson RUnit = Null isContinuation :: RuntimeValue -> Bool isContinuation (RContinuation _) = True isContinuation _ = False getContinuation :: RuntimeValue -> Maybe ContinuationState getContinuation (RContinuation cont) = Just cont getContinuation _ = Nothing -- Convert a Term back to JSON representation termToJson :: Term -> Value termToJson (TInt n) = Number (fromIntegral n) termToJson (TBool b) = Bool b termToJson (TString s) = String s termToJson TUnit = Null termToJson (TVar name) = object ["var" .= name] termToJson (TLam param body) = object [ "lam" .= param , "body" .= termToJson body ] termToJson (TApp func arg) = object [ "app" .= object [ "func" .= termToJson func , "arg" .= termToJson arg ] ] termToJson (TAdd a b) = object ["add" .= [termToJson a, termToJson b]] termToJson (TSub a b) = object ["sub" .= [termToJson a, termToJson b]] termToJson (TMul a b) = object ["mul" .= [termToJson a, termToJson b]] termToJson (TDiv a b) = object ["div" .= [termToJson a, termToJson b]] termToJson (TMod a b) = object ["mod" .= [termToJson a, termToJson b]] termToJson (TEq a b) = object ["eq" .= [termToJson a, termToJson b]] termToJson (TLt a b) = object ["lt" .= [termToJson a, termToJson b]] termToJson (TGt a b) = object ["gt" .= [termToJson a, termToJson b]] termToJson (TLte a b) = object ["lte" .= [termToJson a, termToJson b]] termToJson (TGte a b) = object ["gte" .= [termToJson a, termToJson b]] termToJson (TAnd a b) = object ["and" .= [termToJson a, termToJson b]] termToJson (TOr a b) = object ["or" .= [termToJson a, termToJson b]] termToJson (TNot a) = object ["not" .= termToJson a] termToJson (TIf cond thenBr elseBr) = object [ "if" .= object [ "cond" .= termToJson cond , "then" .= termToJson thenBr , "else" .= termToJson elseBr ] ] termToJson TNil = object ["nil" .= Null] termToJson (TCons h t) = object [ "cons" .= object [ "head" .= termToJson h , "tail" .= termToJson t ] ] termToJson (THead lst) = object ["head" .= termToJson lst] termToJson (TTail lst) = object ["tail" .= termToJson lst] termToJson (TIsEmpty lst) = object ["isEmpty" .= termToJson lst] termToJson (TLength val) = object ["length" .= termToJson val] termToJson (TPair a b) = object ["pair" .= [termToJson a, termToJson b]] termToJson (TFst p) = object ["fst" .= termToJson p] termToJson (TSnd p) = object ["snd" .= termToJson p] termToJson (TConcat a b) = object ["concat" .= [termToJson a, termToJson b]] termToJson TSelf = object ["self" .= Null] termToJson (TContinue input) = object [ "continue" .= object ["input" .= termToJson input] ] termToJson (TFold f init lst) = object [ "fold" .= [termToJson f, termToJson init, termToJson lst] ] termToJson (TQuote t) = object ["quote" .= termToJson t] termToJson (TCodeOf name) = object ["code_of" .= name] termToJson (TEval t) = object ["eval" .= termToJson t]