GHC.Types.Literal

ghc-lib-parser-9.10.1.20250103: The GHC API, decoupled from GHC versions

Safe Haskell | Ignore
Language | GHC2021

GHC.Types.Literal

Contents

- Main data type
  - Creating Literals
  - Operations on Literals
  - Predicates on Literals and their contents
  - Coercions

Description

Core literals

Synopsis

- data Literal
  - = LitChar Char
  - | LitNumber !LitNumType !Integer
  - | LitString !ByteString
  - | LitNullAddr
  - | LitRubbish TypeOrConstraint RuntimeRepType
  - | LitFloat Rational
  - | LitDouble Rational
  - | LitLabel FastString (Maybe Int) FunctionOrData
- data LitNumType
  - = LitNumBigNat
  - | LitNumInt
  - | LitNumInt8
  - | LitNumInt16
  - | LitNumInt32
  - | LitNumInt64
  - | LitNumWord
  - | LitNumWord8
  - | LitNumWord16
  - | LitNumWord32
  - | LitNumWord64
- mkLitInt :: Platform -> Integer -> Literal
- mkLitIntWrap :: Platform -> Integer -> Literal
- mkLitIntWrapC :: Platform -> Integer -> (Literal, Bool)
- mkLitIntUnchecked :: Integer -> Literal
- mkLitWord :: Platform -> Integer -> Literal
- mkLitWordWrap :: Platform -> Integer -> Literal
- mkLitWordWrapC :: Platform -> Integer -> (Literal, Bool)
- mkLitWordUnchecked :: Integer -> Literal
- mkLitInt8 :: Integer -> Literal
- mkLitInt8Wrap :: Integer -> Literal
- mkLitInt8Unchecked :: Integer -> Literal
- mkLitWord8 :: Integer -> Literal
- mkLitWord8Wrap :: Integer -> Literal
- mkLitWord8Unchecked :: Integer -> Literal
- mkLitInt16 :: Integer -> Literal
- mkLitInt16Wrap :: Integer -> Literal
- mkLitInt16Unchecked :: Integer -> Literal
- mkLitWord16 :: Integer -> Literal
- mkLitWord16Wrap :: Integer -> Literal
- mkLitWord16Unchecked :: Integer -> Literal
- mkLitInt32 :: Integer -> Literal
- mkLitInt32Wrap :: Integer -> Literal
- mkLitInt32Unchecked :: Integer -> Literal
- mkLitWord32 :: Integer -> Literal
- mkLitWord32Wrap :: Integer -> Literal
- mkLitWord32Unchecked :: Integer -> Literal
- mkLitInt64 :: Integer -> Literal
- mkLitInt64Wrap :: Integer -> Literal
- mkLitInt64Unchecked :: Integer -> Literal
- mkLitWord64 :: Integer -> Literal
- mkLitWord64Wrap :: Integer -> Literal
- mkLitWord64Unchecked :: Integer -> Literal
- mkLitFloat :: Rational -> Literal
- mkLitDouble :: Rational -> Literal
- mkLitChar :: Char -> Literal
- mkLitString :: String -> Literal
- mkLitBigNat :: Integer -> Literal
- mkLitNumber :: Platform -> LitNumType -> Integer -> Literal
- mkLitNumberWrap :: Platform -> LitNumType -> Integer -> Literal
- mkLitNumberMaybe :: Platform -> LitNumType -> Integer -> Maybe Literal
- literalType :: Literal -> Type
- pprLiteral :: (SDoc -> SDoc) -> Literal -> SDoc
- litNumIsSigned :: LitNumType -> Bool
- litNumRange :: Platform -> LitNumType -> (Maybe Integer, Maybe Integer)
- litNumCheckRange :: Platform -> LitNumType -> Integer -> Bool
- litNumWrap :: Platform -> Literal -> Literal
- litNumCoerce :: LitNumType -> Platform -> Literal -> Literal
- litNumNarrow :: LitNumType -> Platform -> Literal -> Literal
- litNumBitSize :: Platform -> LitNumType -> Maybe Word
- isMinBound :: Platform -> Literal -> Bool
- isMaxBound :: Platform -> Literal -> Bool
- litIsDupable :: Platform -> Literal -> Bool
- litIsTrivial :: Literal -> Bool
- litIsLifted :: Literal -> Bool
- inCharRange :: Char -> Bool
- isZeroLit :: Literal -> Bool
- isOneLit :: Literal -> Bool
- litFitsInChar :: Literal -> Bool
- litValue :: Literal -> Integer
- mapLitValue :: Platform -> (Integer -> Integer) -> Literal -> Literal
- isLitValue_maybe :: Literal -> Maybe Integer
- isLitRubbish :: Literal -> Bool
- narrowInt8Lit :: Literal -> Literal
- narrowInt16Lit :: Literal -> Literal
- narrowInt32Lit :: Literal -> Literal
- narrowInt64Lit :: Literal -> Literal
- narrowWord8Lit :: Literal -> Literal
- narrowWord16Lit :: Literal -> Literal
- narrowWord32Lit :: Literal -> Literal
- narrowWord64Lit :: Literal -> Literal
- convertToIntLit :: Platform -> Literal -> Literal
- convertToWordLit :: Platform -> Literal -> Literal
- charToIntLit :: Literal -> Literal
- intToCharLit :: Literal -> Literal
- floatToIntLit :: Literal -> Literal
- intToFloatLit :: Literal -> Literal
- doubleToIntLit :: Literal -> Literal
- intToDoubleLit :: Literal -> Literal
- nullAddrLit :: Literal
- floatToDoubleLit :: Literal -> Literal
- doubleToFloatLit :: Literal -> Literal

# Main data type

data Literal #

So-called `Literal`s are one of:

- An unboxed numeric literal or floating-point literal which is presumed to be surrounded by appropriate constructors (`Int#`, etc.), so that the overall thing makes sense.

We maintain the invariant that the `Integer` in the `LitNumber` constructor is actually in the (possibly target-dependent) range. The mkLit{Int,Word}*Wrap smart constructors ensure this by applying the target machine's wrapping semantics. Use these in situations where you know the wrapping semantics are correct.

- The literal derived from the label mentioned in a "foreign label" declaration (`LitLabel`)
- A `LitRubbish` to be used in place of values that are never used.
- A character
- A string
- The NULL pointer

Constructors

LitChar Char | `Char#` - at least 31 bits. Create with `mkLitChar`
LitNumber !LitNumType !Integer | Any numeric literal that can be internally represented with an Integer.
LitString !ByteString | A string-literal: stored and emitted UTF-8 encoded, we'll arrange to decode it at runtime. Also emitted with a `'\0'` terminator. Create with `mkLitString`
LitNullAddr | The `NULL` pointer, the only pointer value that can be represented as a Literal. Create with `nullAddrLit`
LitRubbish TypeOrConstraint RuntimeRepType | A nonsense value; See Note [Rubbish literals].
LitFloat Rational | `Float#`. Create with `mkLitFloat`
LitDouble Rational | `Double#`. Create with `mkLitDouble`
LitLabel FastString (Maybe Int) FunctionOrData | A label literal. Parameters: 1) The name of the symbol mentioned in the declaration 2) The size (in bytes) of the arguments the label expects. Only applicable with `stdcall` labels. `Just x` => `<x>` will be appended to label name when emitting assembly. 3) Flag indicating whether the symbol references a function or a data

#### Instances

Instances details

Data Literal # |
Instance details Defined in GHC.Types.Literal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Literal -> c Literal # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Literal # toConstr :: Literal -> Constr # dataTypeOf :: Literal -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Literal) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Literal) # gmapT :: (forall b. Data b => b -> b) -> Literal -> Literal # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Literal -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Literal -> r # gmapQ :: (forall d. Data d => d -> u) -> Literal -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Literal -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Literal -> m Literal # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Literal -> m Literal # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Literal -> m Literal #
Binary Literal # |
Instance details Defined in GHC.Types.Literal Methods put_ :: BinHandle -> Literal -> IO () # put :: BinHandle -> Literal -> IO (Bin Literal) # get :: BinHandle -> IO Literal #
Outputable Literal # |
Instance details Defined in GHC.Types.Literal Methods ppr :: Literal -> SDoc #
Eq Literal # |
Instance details Defined in GHC.Types.Literal Methods (==) :: Literal -> Literal -> Bool # (/=) :: Literal -> Literal -> Bool #
Ord Literal # | Needed for the `Ord` instance of `AltCon`, which in turn is needed in `CoreMap`.
Instance details Defined in GHC.Types.Literal Methods compare :: Literal -> Literal -> Ordering # (<) :: Literal -> Literal -> Bool # (<=) :: Literal -> Literal -> Bool # (>) :: Literal -> Literal -> Bool # (>=) :: Literal -> Literal -> Bool # max :: Literal -> Literal -> Literal # min :: Literal -> Literal -> Literal #

data LitNumType #

Numeric literal type

Constructors

LitNumBigNat | `Bignat` (see Note [BigNum literals])
LitNumInt | `Int#` - according to target machine
LitNumInt8 | `Int8#` - exactly 8 bits
LitNumInt16 | `Int16#` - exactly 16 bits
LitNumInt32 | `Int32#` - exactly 32 bits
LitNumInt64 | `Int64#` - exactly 64 bits
LitNumWord | `Word#` - according to target machine
LitNumWord8 | `Word8#` - exactly 8 bits
LitNumWord16 | `Word16#` - exactly 16 bits
LitNumWord32 | `Word32#` - exactly 32 bits
LitNumWord64 | `Word64#` - exactly 64 bits

#### Instances

Instances details

Data LitNumType # |
Instance details Defined in GHC.Types.Literal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> LitNumType -> c LitNumType # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c LitNumType # toConstr :: LitNumType -> Constr # dataTypeOf :: LitNumType -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c LitNumType) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c LitNumType) # gmapT :: (forall b. Data b => b -> b) -> LitNumType -> LitNumType # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> LitNumType -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> LitNumType -> r # gmapQ :: (forall d. Data d => d -> u) -> LitNumType -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> LitNumType -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> LitNumType -> m LitNumType # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> LitNumType -> m LitNumType # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> LitNumType -> m LitNumType #
Enum LitNumType # |
Instance details Defined in GHC.Types.Literal Methods succ :: LitNumType -> LitNumType # pred :: LitNumType -> LitNumType # toEnum :: Int -> LitNumType # fromEnum :: LitNumType -> Int # enumFrom :: LitNumType -> [LitNumType] # enumFromThen :: LitNumType -> LitNumType -> [LitNumType] # enumFromTo :: LitNumType -> LitNumType -> [LitNumType] # enumFromThenTo :: LitNumType -> LitNumType -> LitNumType -> [LitNumType] #
Binary LitNumType # |
Instance details Defined in GHC.Types.Literal Methods put_ :: BinHandle -> LitNumType -> IO () # put :: BinHandle -> LitNumType -> IO (Bin LitNumType) # get :: BinHandle -> IO LitNumType #
Eq LitNumType # |
Instance details Defined in GHC.Types.Literal Methods (==) :: LitNumType -> LitNumType -> Bool # (/=) :: LitNumType -> LitNumType -> Bool #
Ord LitNumType # |
Instance details Defined in GHC.Types.Literal Methods compare :: LitNumType -> LitNumType -> Ordering # (<) :: LitNumType -> LitNumType -> Bool # (<=) :: LitNumType -> LitNumType -> Bool # (>) :: LitNumType -> LitNumType -> Bool # (>=) :: LitNumType -> LitNumType -> Bool # max :: LitNumType -> LitNumType -> LitNumType # min :: LitNumType -> LitNumType -> LitNumType #

## Creating Literals

mkLitInt :: Platform -> Integer -> Literal #

Creates a `Literal` of type `Int#`

mkLitIntWrap :: Platform -> Integer -> Literal #

Creates a `Literal` of type `Int#`. If the argument is out of the (target-dependent) range, it is wrapped. See Note [WordInt underflowoverflow]

mkLitIntWrapC :: Platform -> Integer -> (Literal, Bool) #

Creates a `Literal` of type `Int#`, as well as a `Bool`ean flag indicating overflow. That is, if the argument is out of the (target-dependent) range the argument is wrapped and the overflow flag will be set. See Note [WordInt underflowoverflow]

mkLitIntUnchecked :: Integer -> Literal #

Creates a `Literal` of type `Int#` without checking its range.

mkLitWord :: Platform -> Integer -> Literal #

Creates a `Literal` of type `Word#`

mkLitWordWrap :: Platform -> Integer -> Literal #

Creates a `Literal` of type `Word#`. If the argument is out of the (target-dependent) range, it is wrapped. See Note [WordInt underflowoverflow]

mkLitWordWrapC :: Platform -> Integer -> (Literal, Bool) #

Creates a `Literal` of type `Word#`, as well as a `Bool`ean flag indicating carry. That is, if the argument is out of the (target-dependent) range the argument is wrapped and the carry flag will be set. See Note [WordInt underflowoverflow]

mkLitWordUnchecked :: Integer -> Literal #

Creates a `Literal` of type `Word#` without checking its range.

mkLitInt8 :: Integer -> Literal #

Creates a `Literal` of type `Int8#`

mkLitInt8Wrap :: Integer -> Literal #

Creates a `Literal` of type `Int8#`. If the argument is out of the range, it is wrapped.

mkLitInt8Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Int8#` without checking its range.

mkLitWord8 :: Integer -> Literal #

Creates a `Literal` of type `Word8#`

mkLitWord8Wrap :: Integer -> Literal #

Creates a `Literal` of type `Word8#`. If the argument is out of the range, it is wrapped.

mkLitWord8Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Word8#` without checking its range.

mkLitInt16 :: Integer -> Literal #

Creates a `Literal` of type `Int16#`

mkLitInt16Wrap :: Integer -> Literal #

Creates a `Literal` of type `Int16#`. If the argument is out of the range, it is wrapped.

mkLitInt16Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Int16#` without checking its range.

mkLitWord16 :: Integer -> Literal #

Creates a `Literal` of type `Word16#`

mkLitWord16Wrap :: Integer -> Literal #

Creates a `Literal` of type `Word16#`. If the argument is out of the range, it is wrapped.

mkLitWord16Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Word16#` without checking its range.

mkLitInt32 :: Integer -> Literal #

Creates a `Literal` of type `Int32#`

mkLitInt32Wrap :: Integer -> Literal #

Creates a `Literal` of type `Int32#`. If the argument is out of the range, it is wrapped.

mkLitInt32Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Int32#` without checking its range.

mkLitWord32 :: Integer -> Literal #

Creates a `Literal` of type `Word32#`

mkLitWord32Wrap :: Integer -> Literal #

Creates a `Literal` of type `Word32#`. If the argument is out of the range, it is wrapped.

mkLitWord32Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Word32#` without checking its range.

mkLitInt64 :: Integer -> Literal #

Creates a `Literal` of type `Int64#`

mkLitInt64Wrap :: Integer -> Literal #

Creates a `Literal` of type `Int64#`. If the argument is out of the range, it is wrapped.

mkLitInt64Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Int64#` without checking its range.

mkLitWord64 :: Integer -> Literal #

Creates a `Literal` of type `Word64#`

mkLitWord64Wrap :: Integer -> Literal #

Creates a `Literal` of type `Word64#`. If the argument is out of the range, it is wrapped.

mkLitWord64Unchecked :: Integer -> Literal #

Creates a `Literal` of type `Word64#` without checking its range.

mkLitFloat :: Rational -> Literal #

Creates a `Literal` of type `Float#`

mkLitDouble :: Rational -> Literal #

Creates a `Literal` of type `Double#`

mkLitChar :: Char -> Literal #

Creates a `Literal` of type `Char#`

mkLitString :: String -> Literal #

Creates a `Literal` of type `Addr#`, which is appropriate for passing to e.g. some of the "error" functions in GHC.Err such as `GHC.Err.runtimeError`

mkLitBigNat :: Integer -> Literal #

mkLitNumber :: Platform -> LitNumType -> Integer -> Literal #

Create a numeric `Literal` of the given type

mkLitNumberWrap :: Platform -> LitNumType -> Integer -> Literal #

Make a literal number using wrapping semantics if the value is out of bound.

mkLitNumberMaybe :: Platform -> LitNumType -> Integer -> Maybe Literal #

Create a numeric `Literal` of the given type if it is in range

## Operations on Literals

literalType :: Literal -> Type #

Find the Haskell `Type` the literal occupies

pprLiteral :: (SDoc -> SDoc) -> Literal -> SDoc #

litNumIsSigned :: LitNumType -> Bool #

Indicate if a numeric literal type supports negative numbers

litNumRange :: Platform -> LitNumType -> (Maybe Integer, Maybe Integer) #

Get the literal range

litNumCheckRange :: Platform -> LitNumType -> Integer -> Bool #

Check that a given number is in the range of a numeric literal

litNumWrap :: Platform -> Literal -> Literal #

Wrap a literal number according to its type using wrapping semantics.

litNumCoerce :: LitNumType -> Platform -> Literal -> Literal #

Coerce a literal number into another using wrapping semantics.

litNumNarrow :: LitNumType -> Platform -> Literal -> Literal #

Narrow a literal number by converting it into another number type and then converting it back to its original type.

litNumBitSize :: Platform -> LitNumType -> Maybe Word #

Number of bits

isMinBound :: Platform -> Literal -> Bool #

isMaxBound :: Platform -> Literal -> Bool #

## Predicates on Literals and their contents

litIsDupable :: Platform -> Literal -> Bool #

True if code space does not go bad if we duplicate this literal

litIsTrivial :: Literal -> Bool #

True if there is absolutely no penalty to duplicating the literal. False principally of strings.

"Why?", you say? I'm glad you asked. Well, for one duplicating strings would blow up code sizes. Not only this, it's also unsafe.

Consider a program that wants to traverse a string. One way it might do this is to first compute the Addr# pointing to the end of the string, and then, starting from the beginning, bump a pointer using eqAddr# to determine the end. For instance,

    -- Given pointers to the start and end of a string, count how many zeros
    -- the string contains.
    countZeros :: Addr# -> Addr# -> -> Int
    countZeros start end = go start 0
      where
        go off n
          | off addrEq# end = n
          | otherwise         = go (off plusAddr# 1) n'
          where n' | isTrue# (indexInt8OffAddr# off 0# ==# 0#) = n + 1
                   | otherwise                                 = n

Consider what happens if we considered strings to be trivial (and therefore duplicable) and emitted a call like `countZeros "hello"# ("hello"# `plusAddr`# 5)`. The beginning and end pointers do not belong to the same string, meaning that an iteration like the above would blow up terribly. This is what happened in #12757.

Ultimately the solution here is to make primitive strings a bit more structured, ensuring that the compiler can't inline in ways that will break user code. One approach to this is described in #8472.

litIsLifted :: Literal -> Bool #

inCharRange :: Char -> Bool #

isZeroLit :: Literal -> Bool #

Tests whether the literal represents a zero of whatever type it is

isOneLit :: Literal -> Bool #

Tests whether the literal represents a one of whatever type it is

litFitsInChar :: Literal -> Bool #

litValue :: Literal -> Integer #

Returns the `Integer` contained in the `Literal`, for when that makes sense, i.e. for `Char` and numbers.

mapLitValue :: Platform -> (Integer -> Integer) -> Literal -> Literal #

Apply a function to the `Integer` contained in the `Literal`, for when that makes sense, e.g. for `Char` and numbers. For fixed-size integral literals, the result will be wrapped in accordance with the semantics of the target type. See Note [WordInt underflowoverflow]

isLitValue_maybe :: Literal -> Maybe Integer #

Returns the `Integer` contained in the `Literal`, for when that makes sense, i.e. for `Char` and numbers.

isLitRubbish :: Literal -> Bool #

## Coercions

narrowInt8Lit :: Literal -> Literal #

narrowInt16Lit :: Literal -> Literal #

narrowInt32Lit :: Literal -> Literal #

narrowInt64Lit :: Literal -> Literal #

narrowWord8Lit :: Literal -> Literal #

narrowWord16Lit :: Literal -> Literal #

narrowWord32Lit :: Literal -> Literal #

narrowWord64Lit :: Literal -> Literal #

convertToIntLit :: Platform -> Literal -> Literal #

Extend or narrow a fixed-width literal (e.g. `Int16#`) to a target word-sized literal (`Int#` or `Word#`). Narrowing can only happen on 32-bit architectures when we convert a 64-bit literal into a 32-bit one.

convertToWordLit :: Platform -> Literal -> Literal #

Extend or narrow a fixed-width literal (e.g. `Int16#`) to a target word-sized literal (`Int#` or `Word#`). Narrowing can only happen on 32-bit architectures when we convert a 64-bit literal into a 32-bit one.

charToIntLit :: Literal -> Literal #

intToCharLit :: Literal -> Literal #

floatToIntLit :: Literal -> Literal #

intToFloatLit :: Literal -> Literal #

doubleToIntLit :: Literal -> Literal #

intToDoubleLit :: Literal -> Literal #

nullAddrLit :: Literal #

floatToDoubleLit :: Literal -> Literal #

doubleToFloatLit :: Literal -> Literal #