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Amélia Liao 9 months ago
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0976be07fc
14 changed files with 519 additions and 0 deletions
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      .gitignore
  2. +30
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      LICENSE
  3. +1
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      README.md
  4. +2
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      Setup.hs
  5. +2
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      hie.yaml
  6. +27
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      layout.cabal
  7. +130
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      src/Lexer.x
  8. +114
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      src/Lexer/Support.hs
  9. +19
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      src/Main.hs
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      src/Parser.y
  11. +17
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      src/Syntax.hs
  12. +67
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      stack.yaml
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      stack.yaml.lock
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      that-code-from-before.hs

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.gitignore View File

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/.stack-work
/.vscode

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LICENSE View File

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Copyright Abigail Magalhães (c) 2021
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of Abigail Magalhães nor the names of other
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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README.md View File

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# layout

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Setup.hs View File

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import Distribution.Simple
main = defaultMain

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hie.yaml View File

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cradle:
stack:

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layout.cabal View File

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name: layout
version: 0.1.0.0
-- synopsis:
-- description:
homepage: https://github.com/plt-hokusai/layout#readme
license: BSD3
license-file: LICENSE
author: Abigail Magalhães
maintainer: [email protected]
copyright: 2021 Abigail Magalhães
category: Web
build-type: Simple
cabal-version: >=1.10
extra-source-files: README.md
executable layout
hs-source-dirs: src
main-is: Main.hs
default-language: Haskell2010
build-depends: base >= 4.7 && < 5
, array >= 0.5 && < 0.6
, mtl
build-tool-depends: alex:alex >= 3.2.4 && < 4.0
, happy:happy >= 1.19.12 && < 2.0
other-modules: Syntax, Lexer, Lexer.Support, Parser

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src/Lexer.x View File

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{
module Lexer where
import Control.Monad.State
import Control.Monad.Error
import Lexer.Support
import Debug.Trace
}
%encoding "latin1"
$lower = [ a-z ]
$upper = [ A-Z ]
@ident = $lower [ $lower $upper _ ' ]*
:-
[\ \t]+ ;
<0> "in" { token TkIn }
<0> "let" { layoutKw TkLet }
<0> "where" { layoutKw TkWhere }
<0> @ident { emit TkIdent }
<0> \\ { token TkBackslash }
<0> "->" { token TkArrow }
<0> \= { token TkEqual }
<0> \( { token TkLParen }
<0> \) { token TkRParen }
<0> \{ { token TkOpen }
<0> \} { token TkClose }
<0> "--" .* \n { \_ -> pushStartCode newline *> scan }
<0> \n { \_ -> pushStartCode newline *> scan }
<layout> {
-- Skip comments and whitespace
"--" .* \n ;
\n ;
\{ { openBrace }
() { startLayout }
}
<empty_layout> () { emptyLayout }
<newline> {
\n ;
"--" .* \n ;
() { offsideRule }
}
<eof> () { doEOF }
{
handleEOF = pushStartCode eof *> scan
doEOF _ = do
t <- Lexer.Support.layout
case t of
Nothing -> do
popStartCode
pure TkEOF
_ -> do
popLayout
pure TkVClose
scan :: Lexer Token
scan = do
[email protected](Input _ _ _ string) <- gets lexerInput
startcode <- startCode
case alexScan input startcode of
AlexEOF -> handleEOF
AlexError (Input _ _ _ inp) ->
throwError $ "Lexical error: " ++ show (head inp)
AlexSkip input' _ -> do
modify' $ \s -> s { lexerInput = input' }
scan
AlexToken input' tokl action -> do
modify' $ \s -> s { lexerInput = input' }
action (take tokl string)
layoutKw t _ = do
pushStartCode Lexer.layout
pure t
openBrace _ = do
popStartCode
pushLayout ExplicitLayout
pure TkOpen
startLayout _ = do
popStartCode
reference <- Lexer.Support.layout
col <- gets (inpColumn . lexerInput)
if Just (LayoutColumn col) <= reference
then pushStartCode empty_layout
else pushLayout (LayoutColumn col)
pure TkVOpen
emptyLayout _ = do
popStartCode
pushStartCode newline
pure TkVClose
offsideRule _ = do
context <- Lexer.Support.layout
col <- gets (inpColumn . lexerInput)
let continue = popStartCode *> scan
case context of
Just (LayoutColumn col') -> do
case col `compare` col' of
EQ -> do
popStartCode
pure TkVSemi
GT -> continue
LT -> do
popLayout
pure TkVClose
_ -> continue
}

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src/Lexer/Support.hs View File

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{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Lexer.Support where
import Data.Word
import Data.List (uncons)
import Data.Char (ord)
import Control.Monad.State
import Data.List.NonEmpty (NonEmpty ((:|)))
import qualified Data.List.NonEmpty as NE
import Control.Monad.Except
data Token
= TkIdent String -- identifiers
-- Keywords
| TkLet | TkIn | TkWhere
-- Punctuation
| TkEqual | TkOpen | TkSemi | TkClose
| TkLParen | TkRParen
| TkBackslash | TkArrow
-- Layout punctuation
| TkVOpen | TkVSemi | TkVClose
| TkEOF
deriving (Eq, Show)
data AlexInput
= Input { inpLine :: {-# UNPACK #-} !Int
, inpColumn :: {-# UNPACK #-} !Int
, inpLast :: {-# UNPACK #-} !Char
, inpStream :: String
}
deriving (Eq, Show)
alexPrevInputChar :: AlexInput -> Char
alexPrevInputChar = inpLast
alexGetByte :: AlexInput -> Maybe (Word8, AlexInput)
alexGetByte inp@Input{inpStream = str} = advance <$> uncons str where
advance ('\n', rest) =
( fromIntegral (ord '\n')
, Input { inpLine = inpLine inp + 1
, inpColumn = 0
, inpLast = '\n'
, inpStream = rest }
)
advance (c, rest) =
( fromIntegral (ord c)
, Input { inpLine = inpLine inp
, inpColumn = inpColumn inp + 1
, inpLast = c
, inpStream = rest }
)
newtype Lexer a = Lexer { _getLexer :: StateT LexerState (Either String) a }
deriving (Functor, Applicative, Monad, MonadState LexerState, MonadError String)
data Layout = ExplicitLayout | LayoutColumn Int
deriving (Eq, Show, Ord)
data LexerState
= LS { lexerInput :: {-# UNPACK #-} !AlexInput
, lexerStartCodes :: {-# UNPACK #-} !(NonEmpty Int)
, lexerLayout :: [Layout]
}
deriving (Eq, Show)
startCode :: Lexer Int
startCode = gets (NE.head . lexerStartCodes)
pushStartCode :: Int -> Lexer ()
pushStartCode i = modify' $ \st ->
st { lexerStartCodes = NE.cons i (lexerStartCodes st)
}
popStartCode :: Lexer ()
popStartCode = modify' $ \st ->
st { lexerStartCodes =
case lexerStartCodes st of
_ :| [] -> 0 :| []
_ :| (x:xs) -> x :| xs
}
layout :: Lexer (Maybe Layout)
layout = gets (fmap fst . uncons . lexerLayout)
pushLayout :: Layout -> Lexer ()
pushLayout i = modify' $ \st ->
st { lexerLayout = i:lexerLayout st }
popLayout :: Lexer ()
popLayout = modify' $ \st ->
st { lexerLayout =
case lexerLayout st of
_:xs -> xs
[] -> []
}
initState :: String -> LexerState
initState str = LS { lexerInput = Input 0 1 '\n' str
, lexerStartCodes = 0 :| []
, lexerLayout = []
}
emit :: (String -> Token) -> String -> Lexer Token
emit = (pure .)
token :: Token -> String -> Lexer Token
token = const . pure
runLexer :: Lexer a -> String -> Either String a
runLexer act s = fst <$> runStateT (_getLexer act) (initState s)

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src/Main.hs View File

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module Main where
import Lexer.Support
import Lexer
import Debug.Trace (traceM)
import Control.Monad.RWS
main :: IO ()
main = do
putStrLn "hello world"
lexAll :: Lexer ()
lexAll = do
tok <- scan
case tok of
TkEOF -> pure ()
x -> do
traceM (show x)
lexAll

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src/Parser.y View File

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{
module Parser where
import Control.Monad.Error
import Lexer.Support
import Syntax
import Lexer (scan)
}
%name parseExpr Expr
%name parseDecl Decl
%tokentype { Token }
%monad { Lexer }
%lexer { lexer } { TkEOF }
%errorhandlertype explist
%error { parseError }
%token
VAR { TkIdent $$ }
'let' { TkLet }
'in' { TkIn }
'where' { TkWhere }
'=' { TkEqual }
'{' { TkOpen }
';' { TkSemi }
'}' { TkClose }
'\\' { TkBackslash }
'->' { TkArrow }
'(' { TkLParen }
')' { TkRParen }
OPEN { TkVOpen }
SEMI { TkVSemi }
CLOSE { TkVClose }
%%
Atom :: { Expr }
: VAR { Var $1 }
| '(' Expr ')' { $2 }
Expr :: { Expr }
: '\\' VAR '->' Expr { Lam $2 $4 }
| 'let' DeclBlock 'in' Expr { Let $2 $4 }
| FuncExpr { $1 }
FuncExpr :: { Expr }
: FuncExpr Atom { App $1 $2 }
| Atom { $1 }
DeclBlock :: { [Decl] }
: '{' DeclListSemi '}' { $2 }
| OPEN DeclListSEMI Close { $2 }
DeclListSemi :: { [Decl] }
: Decl ';' DeclListSemi { $1:$3 }
| Decl { [$1] }
| {- empty -} { [] }
DeclListSEMI :: { [Decl] }
: Decl SEMI DeclListSemi { $1:$3 }
| Decl { [$1] }
| {- empty -} { [] }
Close
: CLOSE { () }
| error {% popLayout }
Decl
: VAR '=' Expr { Decl $1 $3 Nothing }
| VAR '=' Expr 'where' DeclBlock { Decl $1 $3 (Just $5) }
{
lexer cont = scan >>= cont
parseError = throwError . show
}

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src/Syntax.hs View File

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module Syntax (Expr(..), Decl(..), Program) where
data Expr
= Var String
| App Expr Expr
| Lam String Expr
| Let [Decl] Expr
deriving (Eq, Show)
data Decl
= Decl { declName :: String
, declRhs :: Expr
, declWhere :: Maybe [Decl]
}
deriving (Eq, Show)
type Program = [Decl]

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stack.yaml View File

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# This file was automatically generated by 'stack init'
#
# Some commonly used options have been documented as comments in this file.
# For advanced use and comprehensive documentation of the format, please see:
# https://docs.haskellstack.org/en/stable/yaml_configuration/
# Resolver to choose a 'specific' stackage snapshot or a compiler version.
# A snapshot resolver dictates the compiler version and the set of packages
# to be used for project dependencies. For example:
#
# resolver: lts-3.5
# resolver: nightly-2015-09-21
# resolver: ghc-7.10.2
#
# The location of a snapshot can be provided as a file or url. Stack assumes
# a snapshot provided as a file might change, whereas a url resource does not.
#
# resolver: ./custom-snapshot.yaml
# resolver: https://example.com/snapshots/2018-01-01.yaml
resolver:
url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/4.yaml
# User packages to be built.
# Various formats can be used as shown in the example below.
#
# packages:
# - some-directory
# - https://example.com/foo/bar/baz-0.0.2.tar.gz
# subdirs:
# - auto-update
# - wai
packages:
- .
# Dependency packages to be pulled from upstream that are not in the resolver.
# These entries can reference officially published versions as well as
# forks / in-progress versions pinned to a git hash. For example:
#
# extra-deps:
# - acme-missiles-0.3
# - git: https://github.com/commercialhaskell/stack.git
# commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
#
# extra-deps: []
# Override default flag values for local packages and extra-deps
# flags: {}
# Extra package databases containing global packages
# extra-package-dbs: []
# Control whether we use the GHC we find on the path
# system-ghc: true
#
# Require a specific version of stack, using version ranges
# require-stack-version: -any # Default
# require-stack-version: ">=2.7"
#
# Override the architecture used by stack, especially useful on Windows
# arch: i386
# arch: x86_64
#
# Extra directories used by stack for building
# extra-include-dirs: [/path/to/dir]
# extra-lib-dirs: [/path/to/dir]
#
# Allow a newer minor version of GHC than the snapshot specifies
# compiler-check: newer-minor

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stack.yaml.lock View File

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# This file was autogenerated by Stack.
# You should not edit this file by hand.
# For more information, please see the documentation at:
# https://docs.haskellstack.org/en/stable/lock_files
packages: []
snapshots:
- completed:
size: 585817
url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/4.yaml
sha256: ea3a318eafa9e9cc56bfbe46099fd0d54d32641ab7bbe1d182ed8f5de39f804c
original:
url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/4.yaml

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that-code-from-before.hs View File

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Right
(Decl { declName = "foo"
, declRhs =
Let [ Decl { declName = "x"
, declRhs =
Let
[ Decl {declName = "y", declRhs = Var "z", declWhere = Nothing} ]
(Var "y")
, declWhere = Nothing
}
]
(Var "x")
, declWhere = Nothing
})

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