Language/Symantic/AST/Test.hs

   1 {-# LANGUAGE FlexibleContexts #-}
   2 {-# LANGUAGE FlexibleInstances #-}
   3 {-# LANGUAGE GADTs #-}
   4 {-# LANGUAGE MultiParamTypeClasses #-}
   5 {-# LANGUAGE OverloadedStrings #-}
   6 {-# LANGUAGE Rank2Types #-}
   7 {-# LANGUAGE ScopedTypeVariables #-}
   8 {-# LANGUAGE TypeFamilies #-}
   9 {-# LANGUAGE UndecidableInstances #-}
  10 -- | Abstract Syntax Tree.
  11 module AST.Test where
  12
  13 import Test.Tasty
  14 -- import Test.Tasty.HUnit
  15
  16 import qualified Data.List as List
  17 import Data.Proxy (Proxy(..))
  18 import Data.Text (Text)
  19 import qualified Data.Text as Text
  20
  21 import Language.Symantic.Type
  22 import Language.Symantic.Expr as Expr
  23
  24 tests :: TestTree
  25 tests = testGroup "AST" $
  26  [
  27  ]
  28
  29 -- * Type 'AST'
  30 data AST
  31  =   AST Text [AST]
  32  deriving (Eq)
  33 -- | Custom 'Show' instance a little bit more readable
  34 -- than the automatically derived one.
  35 instance Show AST where
  36         showsPrec p ast@(AST f args) =
  37                 let n = Text.unpack f in
  38                 case ast of
  39                  AST _ [] -> showString n
  40                  AST "->" [a] ->
  41                                 showParen (p >= prec_arrow) $
  42                                 showString ("("++n++") ") .
  43                                 showsPrec prec_arrow a
  44                  AST "->" [a, b] ->
  45                                 showParen (p >= prec_arrow) $
  46                                 showsPrec prec_arrow a .
  47                                 showString (" "++n++" ") .
  48                                 showsPrec prec_arrow b
  49                  _ ->
  50                         showString n .
  51                         showString "(" .
  52                         showString (List.intercalate ", " $ show <$> args) .
  53                         showString ")"
  54                 where prec_arrow = 1
  55
  56 -- ** Parsing utilities
  57 from_ast0
  58  :: forall ty ast ex hs ret.
  59  ( ty ~ Type_Root_of_Expr ex
  60  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  61                    (Error_of_Expr ast (Root_of_Expr ex))
  62  ) => [ast]
  63  -> Expr_From ast ex hs ret
  64  -> Expr_From ast ex hs ret
  65 from_ast0 asts k' ex ast ctx k =
  66         case asts of
  67          [] -> k' ex ast ctx k
  68          _ -> Left $ error_expr ex $
  69                 Error_Expr_Wrong_number_of_arguments ast 0
  70
  71 from_ast1
  72  :: forall ty ast ex hs ret.
  73  ( ty ~ Type_Root_of_Expr ex
  74  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  75                    (Error_of_Expr ast (Root_of_Expr ex))
  76  ) => [ast] -> (ast -> Expr_From ast ex hs ret)
  77  -> Expr_From ast ex hs ret
  78 from_ast1 asts k' ex ast ctx k =
  79         case asts of
  80          [ast_0] -> k' ast_0 ex ast ctx k
  81          _ -> Left $ error_expr ex $
  82                 Error_Expr_Wrong_number_of_arguments ast 1
  83
  84 from_ast2
  85  :: forall ty ast ex hs ret.
  86  ( ty ~ Type_Root_of_Expr ex
  87  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
  88                    (Error_of_Expr ast (Root_of_Expr ex))
  89  ) => [ast] -> (ast -> ast -> Expr_From ast ex hs ret)
  90  -> Expr_From ast ex hs ret
  91 from_ast2 asts k' ex ast ctx k =
  92         case asts of
  93          [ast_0, ast_1] -> k' ast_0 ast_1 ex ast ctx k
  94          _ -> Left $ error_expr ex $
  95                 Error_Expr_Wrong_number_of_arguments ast 2
  96
  97 from_ast3
  98  :: forall ty ast ex hs ret.
  99  ( ty ~ Type_Root_of_Expr ex
 100  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
 101                    (Error_of_Expr ast (Root_of_Expr ex))
 102  ) => [ast] -> (ast -> ast -> ast -> Expr_From ast ex hs ret)
 103  -> Expr_From ast ex hs ret
 104 from_ast3 asts k' ex ast ctx k =
 105         case asts of
 106          [ast_0, ast_1, ast_2] -> k' ast_0 ast_1 ast_2 ex ast ctx k
 107          _ -> Left $ error_expr ex $
 108                 Error_Expr_Wrong_number_of_arguments ast 3
 109
 110 lit_from_AST
 111  :: forall root ty lit ex ast hs ret.
 112  ( ty ~ Type_Root_of_Expr ex
 113  , root ~ Root_of_Expr ex
 114  , ast ~ AST
 115  , Read lit
 116  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
 117                    (Error_of_Expr ast root)
 118  ) => (forall repr. Sym_of_Expr ex repr => lit -> repr lit)
 119  -> ty lit -> [ast]
 120  -> Expr_From ast ex hs ret
 121 lit_from_AST op ty_lit asts ex ast ctx k =
 122         case asts of
 123          [AST lit []] -> lit_from op ty_lit lit ex ast ctx k
 124          _ -> Left $ error_expr ex $
 125                 Error_Expr_Wrong_number_of_arguments ast 1
 126
 127 op1_from_AST
 128  :: forall root ty lit ex ast hs ret.
 129  ( ty ~ Type_Root_of_Expr ex
 130  , root ~ Root_of_Expr ex
 131  , ast ~ AST
 132  , Eq_Type (Type_Root_of_Expr root)
 133  , Expr_from ast root
 134  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
 135                    (Error_of_Expr ast root)
 136  , Root_of_Expr root ~ root
 137  ) => (forall repr. Sym_of_Expr ex repr => repr lit -> repr lit)
 138  -> ty lit -> [ast]
 139  -> Expr_From ast ex hs ret
 140 op1_from_AST op ty_lit asts ex ast ctx k =
 141         case asts of
 142          [ast_x] -> op1_from op ty_lit ast_x ex ast ctx k
 143          _ -> Left $ error_expr ex $
 144                 Error_Expr_Wrong_number_of_arguments ast 1
 145
 146 op2_from_AST
 147  :: forall root ty lit ex ast hs ret.
 148  ( ty ~ Type_Root_of_Expr ex
 149  , root ~ Root_of_Expr ex
 150  , ast ~ AST
 151  , Eq_Type (Type_Root_of_Expr root)
 152  , Expr_from ast root
 153  , Error_Expr_Lift (Error_Expr (Error_of_Type ast ty) ty ast)
 154                    (Error_of_Expr ast root)
 155  , Root_of_Expr root ~ root
 156  ) => (forall repr. Sym_of_Expr ex repr => repr lit -> repr lit -> repr lit)
 157  -> ty lit -> [ast]
 158  -> Expr_From ast ex hs ret
 159 op2_from_AST op ty_lit asts ex ast ctx k =
 160         case asts of
 161          [ast_x, ast_y] -> op2_from op ty_lit ast_x ast_y ex ast ctx k
 162          _ -> Left $ error_expr ex $
 163                 Error_Expr_Wrong_number_of_arguments ast 2
 164
 165 instance -- Type_from AST Type_Var
 166  ( Error_Type_Lift (Error_Type AST) (Error_of_Type AST root)
 167  , Implicit_HBool (Is_Last_Type (Type_Var root) root)
 168  ) => Type_from AST (Type_Var root) where
 169         type_from ty ast _k =
 170                 Left $ error_type_unsupported ty ast
 171          -- NOTE: no support so far.
 172 instance -- Type_from AST Type_Unit
 173  ( Type_Root_Lift Type_Unit root
 174  , Error_Type_Lift (Error_Type AST) (Error_of_Type AST root)
 175  , Implicit_HBool (Is_Last_Type (Type_Unit root) root)
 176  ) => Type_from AST (Type_Unit root) where
 177         type_from ty ast k =
 178                 case ast of
 179                  AST "()" asts ->
 180                         case asts of
 181                          [] -> k type_unit
 182                          _ -> Left $ error_type_lift $
 183                                 Error_Type_Wrong_number_of_arguments ast 0
 184                  _ -> Left $ error_type_unsupported ty ast
 185 instance -- Type_from AST Type_Bool
 186  ( Type_Root_Lift Type_Bool root
 187  , Error_Type_Lift (Error_Type AST) (Error_of_Type AST root)
 188  , Implicit_HBool (Is_Last_Type (Type_Bool root) root)
 189  ) => Type_from AST (Type_Bool root) where
 190         type_from ty ast k =
 191                 case ast of
 192                  AST "Bool" asts ->
 193                         case asts of
 194                          [] -> k type_bool
 195                          _ -> Left $ error_type_lift $
 196                                 Error_Type_Wrong_number_of_arguments ast 0
 197                  _ -> Left $ error_type_unsupported ty ast
 198 instance -- Type_from AST Type_Int
 199  ( Type_Root_Lift Type_Int root
 200  , Error_Type_Lift (Error_Type AST) (Error_of_Type AST root)
 201  , Implicit_HBool (Is_Last_Type (Type_Int root) root)
 202  ) => Type_from AST (Type_Int root) where
 203         type_from ty ast k =
 204                 case ast of
 205                  AST "Int" asts ->
 206                         case asts of
 207                          [] -> k type_int
 208                          _ -> Left $ error_type_lift $
 209                                 Error_Type_Wrong_number_of_arguments ast 0
 210                  _ -> Left $ error_type_unsupported ty ast
 211 instance -- Type_from AST Type_Fun
 212  ( Eq_Type root
 213  , Type_from AST root
 214  , Type_Root_Lift (Type_Fun lam) root
 215  , Error_Type_Lift   (Error_Type AST) (Error_of_Type AST root)
 216  , Error_Type_Unlift (Error_Type AST) (Error_of_Type AST root)
 217  , Root_of_Type root ~ root
 218  , Implicit_HBool (Is_Last_Type (Type_Fun lam root) root)
 219  ) => Type_from AST (Type_Fun lam root) where
 220         type_from ty ast k =
 221                 case ast of
 222                  AST "->" asts ->
 223                         case asts of
 224                          [ast_arg, ast_res] -> type_fun_from ty ast_arg ast_res k
 225                          _ -> Left $ error_type_lift $
 226                                 Error_Type_Wrong_number_of_arguments ast 2
 227                  _ -> Left $ error_type_unsupported ty ast
 228 instance -- Type_from AST Type_Maybe
 229  ( Eq_Type root
 230  , Type_from AST root
 231  , Type_Root_Lift Type_Maybe root
 232  , Error_Type_Lift   (Error_Type AST) (Error_of_Type AST root)
 233  , Error_Type_Unlift (Error_Type AST) (Error_of_Type AST root)
 234  , Root_of_Type root ~ root
 235  , Implicit_HBool (Is_Last_Type (Type_Maybe root) root)
 236  ) => Type_from AST (Type_Maybe root) where
 237         type_from ty ast k =
 238                 case ast of
 239                  AST "Maybe" asts ->
 240                         case asts of
 241                          [ast_a] ->
 242                                 type_from (Proxy::Proxy root) ast_a $ \ty_a ->
 243                                         k (type_maybe ty_a)
 244                          _ -> Left $ error_type_lift $
 245                                 Error_Type_Wrong_number_of_arguments ast 1
 246                  _ -> Left $ error_type_unsupported ty ast
 247 instance -- Type_from AST Type_List
 248  ( Eq_Type root
 249  , Type_from AST root
 250  , Type_Root_Lift Type_List root
 251  , Error_Type_Lift   (Error_Type AST) (Error_of_Type AST root)
 252  , Error_Type_Unlift (Error_Type AST) (Error_of_Type AST root)
 253  , Root_of_Type root ~ root
 254  , Implicit_HBool (Is_Last_Type (Type_List root) root)
 255  ) => Type_from AST (Type_List root) where
 256         type_from ty ast k =
 257                 case ast of
 258                  AST "[]" asts ->
 259                         case asts of
 260                          [ast_a] ->
 261                                 type_from (Proxy::Proxy root) ast_a $ \ty_a ->
 262                                         k (type_list ty_a)
 263                          _ -> Left $ error_type_lift $
 264                                 Error_Type_Wrong_number_of_arguments ast 1
 265                  _ -> Left $ error_type_unsupported ty ast
 266 instance -- Expr_from AST Expr_Bool
 267  ( Type_from AST (Type_Root_of_Expr root)
 268  , Expr_from AST root
 269  , Type_Root_Lift Type_Bool (Type_Root_of_Expr root)
 270  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 271  , Type_Unlift Type_Bool (Type_of_Expr root)
 272  , Root_of_Expr root ~ root
 273  , Implicit_HBool (Is_Last_Expr (Expr_Bool root) root)
 274  ) => Expr_from AST (Expr_Bool root) where
 275         expr_from ex ast =
 276                 case ast of
 277                  AST "bool" asts -> lit_from_AST bool      type_bool asts ex ast
 278                  AST "not"  asts -> op1_from_AST Expr.not  type_bool asts ex ast
 279                  AST "&&"   asts -> op2_from_AST (Expr.&&) type_bool asts ex ast
 280                  AST "||"   asts -> op2_from_AST (Expr.||) type_bool asts ex ast
 281                  AST "xor"  asts -> op2_from_AST Expr.xor  type_bool asts ex ast
 282                  _ -> \_ctx _k -> Left $ error_expr_unsupported ex ast
 283 instance -- Expr_from AST Expr_If
 284  ( Type_from AST (Type_Root_of_Expr root)
 285  , Expr_from AST root
 286  , Type_Root_Lift Type_Bool (Type_Root_of_Expr root)
 287  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 288  , Root_of_Expr root ~ root
 289  , Implicit_HBool (Is_Last_Expr (Expr_If root) root)
 290  ) => Expr_from AST (Expr_If root) where
 291         expr_from ex ast ctx k =
 292                 case ast of
 293                  AST "if" asts -> from_ast3 asts if_from ex ast ctx k
 294                  _ -> Left $ error_expr_unsupported ex ast
 295 instance -- Expr_from AST Expr_When
 296  ( Type_from AST (Type_Root_of_Expr root)
 297  , Expr_from AST root
 298  , Type_Root_Lift Type_Bool (Type_Root_of_Expr root)
 299  , Type_Root_Lift Type_Unit (Type_Root_of_Expr root)
 300  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 301  , Root_of_Expr root ~ root
 302  , Implicit_HBool (Is_Last_Expr (Expr_When root) root)
 303  ) => Expr_from AST (Expr_When root) where
 304         expr_from ex ast ctx k =
 305                 case ast of
 306                  AST "when" asts -> from_ast2 asts when_from ex ast ctx k
 307                  _ -> Left $ error_expr_unsupported ex ast
 308 instance -- Expr_from AST Expr_Int
 309  ( Type_from AST (Type_Root_of_Expr root)
 310  , Expr_from AST root
 311  , Type_Root_Lift Type_Int (Type_Root_of_Expr root)
 312  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 313  , Type_Unlift Type_Int (Type_of_Expr root)
 314  , Root_of_Expr root ~ root
 315  , Implicit_HBool (Is_Last_Expr (Expr_Int root) root)
 316  ) => Expr_from AST (Expr_Int root) where
 317         expr_from ex ast =
 318                 case ast of
 319                  AST "int"    asts -> lit_from_AST int         type_int asts ex ast
 320                  AST "abs"    asts -> op1_from_AST Expr.abs    type_int asts ex ast
 321                  AST "negate" asts -> op1_from_AST Expr.negate type_int asts ex ast
 322                  AST "+"      asts -> op2_from_AST (Expr.+)    type_int asts ex ast
 323                  AST "-"      asts -> op2_from_AST (Expr.-)    type_int asts ex ast
 324                  AST "*"      asts -> op2_from_AST (Expr.*)    type_int asts ex ast
 325                  AST "mod"    asts -> op2_from_AST Expr.mod    type_int asts ex ast
 326                  _ -> \_ctx _k -> Left $ error_expr_unsupported ex ast
 327 instance -- Expr_from AST Expr_Lambda
 328  ( Type_from AST (Type_Root_of_Expr root)
 329  , Expr_from AST root
 330  , Type_Root_Lift (Type_Fun lam) (Type_Root_of_Expr root)
 331  , Error_Expr_Lift (Error_Expr_Lambda AST)       (Error_of_Expr AST root)
 332  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 333  , Type_Unlift (Type_Fun lam) (Type_of_Expr root)
 334  , Root_of_Expr root ~ root
 335  , Implicit_HBool (Is_Last_Expr (Expr_Lambda lam root) root)
 336  ) => Expr_from AST (Expr_Lambda lam root) where
 337         expr_from ex ast ctx k =
 338                 case ast of
 339                  AST "var" asts ->
 340                         case asts of
 341                          [AST name []] -> var_from name ex ast ctx k
 342                          _ -> Left $ error_expr ex $
 343                                 Error_Expr_Wrong_number_of_arguments ast 1
 344                  AST "app"        asts -> from_ast2 asts app_from ex ast ctx k
 345                  AST "inline"     asts -> go_lam asts inline
 346                  AST "val"        asts -> go_lam asts val
 347                  AST "lazy"       asts -> go_lam asts lazy
 348                  AST "let_inline" asts -> go_let asts let_inline
 349                  AST "let_val"    asts -> go_let asts let_val
 350                  AST "let_lazy"   asts -> go_let asts let_lazy
 351                  _ -> Left $ error_expr_unsupported ex ast
 352                 where
 353                 go_lam asts
 354                  (lam::forall repr arg res. Sym_Lambda lam repr
 355                      => (repr arg -> repr res) -> repr (Lambda lam arg res)) =
 356                         case asts of
 357                          [AST name [], ast_ty_arg, ast_body] ->
 358                                 lam_from lam name ast_ty_arg ast_body ex ast ctx k
 359                          _ -> Left $ error_expr ex $
 360                                 Error_Expr_Wrong_number_of_arguments ast 3
 361                 go_let asts
 362                  (let_::forall repr var res. Sym_Lambda lam repr
 363                      => repr var -> (repr var -> repr res) -> repr res) =
 364                         case asts of
 365                          [AST name [], ast_var, ast_body] ->
 366                                 let_from let_ name ast_var ast_body ex ast ctx k
 367                          _ -> Left $ error_expr ex $
 368                                 Error_Expr_Wrong_number_of_arguments ast 3
 369 instance -- Expr_from AST Expr_Maybe
 370  ( Type_from AST (Type_Root_of_Expr root)
 371  , Expr_from AST root
 372  , Type_Lift   (Type_Fun lam) (Type_of_Expr root)
 373  , Type_Unlift (Type_Fun lam) (Type_of_Expr root)
 374  , Type_Lift   Type_Maybe     (Type_of_Expr root)
 375  , Type_Unlift Type_Maybe     (Type_of_Expr root)
 376  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 377  , Root_of_Expr root ~ root
 378  , Implicit_HBool (Is_Last_Expr (Expr_Maybe lam root) root)
 379  ) => Expr_from AST (Expr_Maybe lam root) where
 380         expr_from ex ast ctx k =
 381                 case ast of
 382                  AST "maybe"   asts -> from_ast3 asts maybe_from   ex ast ctx k
 383                  AST "nothing" asts -> from_ast1 asts nothing_from ex ast ctx k
 384                  AST "just"    asts -> from_ast1 asts just_from    ex ast ctx k
 385                  _ -> Left $ error_expr_unsupported ex ast
 386 instance -- Expr_from AST Expr_Eq
 387  ( Type_from AST (Type_Root_of_Expr root)
 388  , Type_Lift Type_Bool (Type_of_Expr root)
 389  , Constraint_Type Eq (Type_Root_of_Expr root)
 390  , Expr_from AST root
 391  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 392  , Root_of_Expr root ~ root
 393  , Implicit_HBool (Is_Last_Expr (Expr_Eq root) root)
 394  ) => Expr_from AST (Expr_Eq root) where
 395         expr_from ex ast ctx k =
 396                 case ast of
 397                  AST "==" asts -> from_ast2 asts eq_from ex ast ctx k
 398                  _ -> Left $ error_expr_unsupported ex ast
 399 instance -- Expr_from AST Expr_Ord
 400  ( Type_from AST (Type_Root_of_Expr root)
 401  , Type_Lift Type_Ordering (Type_of_Expr root)
 402  , Constraint_Type Ord (Type_Root_of_Expr root)
 403  , Expr_from AST root
 404  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 405  , Root_of_Expr root ~ root
 406  , Implicit_HBool (Is_Last_Expr (Expr_Ord root) root)
 407  ) => Expr_from AST (Expr_Ord root) where
 408         expr_from ex ast ctx k =
 409                 case ast of
 410                  AST "compare" asts -> from_ast2 asts compare_from ex ast ctx k
 411                  _ -> Left $ error_expr_unsupported ex ast
 412 instance -- Expr_from AST Expr_List
 413  ( Type_from AST (Type_Root_of_Expr root)
 414  , Expr_from AST root
 415  , Type_Lift   (Type_Fun lam) (Type_of_Expr root)
 416  , Type_Unlift (Type_Fun lam) (Type_of_Expr root)
 417  , Type_Lift   Type_List      (Type_of_Expr root)
 418  , Type_Unlift Type_List      (Type_of_Expr root)
 419  , Type_Lift   Type_Bool      (Type_of_Expr root)
 420  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 421  , Root_of_Expr root ~ root
 422  , Implicit_HBool (Is_Last_Expr (Expr_List lam root) root)
 423  ) => Expr_from AST (Expr_List lam root) where
 424         expr_from ex ast ctx k =
 425                 case ast of
 426                  AST "[]"          asts -> from_ast1 asts list_empty_from  ex ast ctx k
 427                  AST ":"           asts -> from_ast2 asts list_cons_from   ex ast ctx k
 428                  AST "list_filter" asts -> from_ast2 asts list_filter_from ex ast ctx k
 429                  AST "list"        asts ->
 430                         case asts of
 431                          ast_ty_a:asts' -> list_from ast_ty_a asts' ex ast ctx k
 432                          _ -> Left $ error_expr ex $
 433                                 Error_Expr_Wrong_number_of_arguments ast 1
 434                  _ -> Left $ error_expr_unsupported ex ast
 435 instance -- Expr_from AST Expr_Map
 436  ( Type_from AST (Type_Root_of_Expr root)
 437  , Expr_from AST root
 438  , Type_Lift   (Type_Fun lam) (Type_of_Expr root)
 439  , Type_Unlift (Type_Fun lam) (Type_of_Expr root)
 440  , Type_Lift   Type_Map       (Type_of_Expr root)
 441  , Type_Unlift Type_Map       (Type_of_Expr root)
 442  , Type_Lift   Type_List      (Type_of_Expr root)
 443  , Type_Unlift Type_List      (Type_of_Expr root)
 444  , Type_Lift   Type_Tuple2    (Type_of_Expr root)
 445  , Type_Unlift Type_Tuple2    (Type_of_Expr root)
 446  , Constraint_Type Ord (Type_Root_of_Expr root)
 447  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 448  , Root_of_Expr root ~ root
 449  , Implicit_HBool (Is_Last_Expr (Expr_Map lam root) root)
 450  ) => Expr_from AST (Expr_Map lam root) where
 451         expr_from ex ast ctx k =
 452                 case ast of
 453                  AST "map_from_list" asts -> from_ast1 asts map_from_list_from ex ast ctx k
 454                  AST "map_map" asts -> from_ast2 asts map_map_from ex ast ctx k
 455                  _ -> Left $ error_expr_unsupported ex ast
 456 instance -- Expr_from AST Expr_Functor
 457  ( Type_from AST (Type_Root_of_Expr root)
 458  , Expr_from AST root
 459  , Type_Lift   (Type_Fun lam) (Type_of_Expr root)
 460  , Type_Unlift (Type_Fun lam) (Type_of_Expr root)
 461  , Type_Unlift1 (Type_of_Expr root)
 462  , Error_Expr_Lift (Error_Expr_of_Root AST root) (Error_of_Expr AST root)
 463  , Constraint1_Type Functor_with_Lambda (Type_Root_of_Expr root)
 464  , Root_of_Expr root ~ root
 465  , Implicit_HBool (Is_Last_Expr (Expr_Functor lam root) root)
 466  ) => Expr_from AST (Expr_Functor lam root) where
 467         expr_from ex ast ctx k =
 468                 case ast of
 469                  AST "fmap" asts -> from_ast2 asts fmap_from ex ast ctx k
 470                  _ -> Left $ error_expr_unsupported ex ast