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|
{-# OPTIONS_GHC -Wno-missing-export-lists #-}
module Builtins where
import qualified Data.Map as M
import Control.Monad.Except ( when, MonadError(throwError) )
import Types
builtinEnv :: Env
builtinEnv = M.fromList [
("+", builtinAdd2),
("-", builtinSubtract2),
("*", builtinMultiply2),
("/", builtinDivide2),
("head", builtinHead),
("tail", builtinTail),
("prepend", builtinPrepend)
]
builtinAdd2 :: AST
builtinAdd2 =
let outer _ ast1 = do
(ASTInteger a) <- assertIsASTInteger ast1
let inner _ ast2 = do
(ASTInteger b) <- assertIsASTInteger ast2
return $ ASTInteger $ a + b
return $ ASTFunction $ inner
in ASTFunction outer
builtinSubtract2 :: AST
builtinSubtract2 =
let outer _ ast1 = do
(ASTInteger a) <- assertIsASTInteger ast1
let inner _ ast2 = do
(ASTInteger b) <- assertIsASTInteger ast2
return $ ASTInteger $ a - b
return $ ASTFunction $ inner
in ASTFunction outer
builtinMultiply2 :: AST
builtinMultiply2 =
let outer _ ast1 = do
(ASTInteger a) <- assertIsASTInteger ast1
let inner _ ast2 = do
(ASTInteger b) <- assertIsASTInteger ast2
return $ ASTInteger $ a * b
return $ ASTFunction $ inner
in ASTFunction outer
builtinDivide2 :: AST
builtinDivide2 =
let outer _ ast1 = do
(ASTInteger a) <- assertIsASTInteger ast1
let inner _ ast2 = do
(ASTInteger b) <- assertIsASTInteger ast2
when (b == 0) $ throwError $ LException $ "division by zero"
return $ ASTInteger $ a `div` b
return $ ASTFunction $ inner
in ASTFunction outer
builtinHead :: AST
builtinHead =
let outer _ ast = do
(ASTVector vec) <- assertIsASTVector ast
when (length vec == 0) $ throwError $ LException $ "head of empty vector"
return $ head vec
in ASTFunction outer
builtinTail :: AST
builtinTail =
let outer _ ast = do
(ASTVector vec) <- assertIsASTVector ast
when (length vec == 0) $ throwError $ LException $ "tail of empty vector"
return $ ASTVector $ tail vec
in ASTFunction outer
builtinPrepend :: AST
builtinPrepend =
let outer _ ast1 = do
let inner _ ast2 = do
(ASTVector vec) <- assertIsASTVector ast2
return $ ASTVector $ ast1 : vec
return $ ASTFunction $ inner
in ASTFunction outer
|
