\section[HsLit]{Abstract syntax: source-language literals}
\begin{code}
+{-# LANGUAGE DeriveDataTypeable #-}
+
module HsLit where
#include "HsVersions.h"
import {-# SOURCE #-} HsExpr( SyntaxExpr, pprExpr )
-import HsTypes (PostTcType)
+import BasicTypes ( FractionalLit(..) )
+import HsTypes ( PostTcType )
import Type ( Type )
import Outputable
import FastString
-import Ratio ( Rational )
+
+import Data.Data
\end{code}
| HsWordPrim Integer -- Unboxed Word
| HsInteger Integer Type -- Genuinely an integer; arises only from TRANSLATION
-- (overloaded literals are done with HsOverLit)
- | HsRat Rational Type -- Genuinely a rational; arises only from TRANSLATION
+ | HsRat FractionalLit Type -- Genuinely a rational; arises only from TRANSLATION
-- (overloaded literals are done with HsOverLit)
- | HsFloatPrim Rational -- Unboxed Float
- | HsDoublePrim Rational -- Unboxed Double
+ | HsFloatPrim FractionalLit -- Unboxed Float
+ | HsDoublePrim FractionalLit -- Unboxed Double
+ deriving (Data, Typeable)
instance Eq HsLit where
(HsChar x1) == (HsChar x2) = x1==x2
_ == _ = False
data HsOverLit id -- An overloaded literal
- = HsIntegral !Integer (SyntaxExpr id) PostTcType -- Integer-looking literals;
- | HsFractional !Rational (SyntaxExpr id) PostTcType -- Frac-looking literals
- | HsIsString !FastString (SyntaxExpr id) PostTcType -- String-looking literals
- -- Before type checking, the SyntaxExpr is 'fromInteger' or 'fromRational'
- -- After type checking, it is (fromInteger 3) or lit_78; that is,
- -- the expression that should replace the literal.
- -- This is unusual, because we're replacing 'fromInteger' with a call
- -- to fromInteger. Reason: it allows commoning up of the fromInteger
- -- calls, which wouldn't be possible if the desguarar made the application
- --
- -- The PostTcType in each branch records the type the overload literal is
- -- found to have.
-
-overLitExpr :: HsOverLit id -> SyntaxExpr id
-overLitExpr (HsIntegral _ e _) = e
-overLitExpr (HsFractional _ e _) = e
-overLitExpr (HsIsString _ e _) = e
-
-overLitType :: HsOverLit id -> PostTcType
-overLitType (HsIntegral _ _ t) = t
-overLitType (HsFractional _ _ t) = t
-overLitType (HsIsString _ _ t) = t
+ = OverLit {
+ ol_val :: OverLitVal,
+ ol_rebindable :: Bool, -- Note [ol_rebindable]
+ ol_witness :: SyntaxExpr id, -- Note [Overloaded literal witnesses]
+ ol_type :: PostTcType }
+ deriving (Data, Typeable)
+
+data OverLitVal
+ = HsIntegral !Integer -- Integer-looking literals;
+ | HsFractional !FractionalLit -- Frac-looking literals
+ | HsIsString !FastString -- String-looking literals
+ deriving (Data, Typeable)
+
+overLitType :: HsOverLit a -> Type
+overLitType = ol_type
+\end{code}
+
+Note [ol_rebindable]
+~~~~~~~~~~~~~~~~~~~~
+The ol_rebindable field is True if this literal is actually
+using rebindable syntax. Specifically:
+
+ False iff ol_witness is the standard one
+ True iff ol_witness is non-standard
+
+Equivalently it's True if
+ a) RebindableSyntax is on
+ b) the witness for fromInteger/fromRational/fromString
+ that happens to be in scope isn't the standard one
+Note [Overloaded literal witnesses]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+*Before* type checking, the SyntaxExpr in an HsOverLit is the
+name of the coercion function, 'fromInteger' or 'fromRational'.
+*After* type checking, it is a witness for the literal, such as
+ (fromInteger 3) or lit_78
+This witness should replace the literal.
+This dual role is unusual, because we're replacing 'fromInteger' with
+a call to fromInteger. Reason: it allows commoning up of the fromInteger
+calls, which wouldn't be possible if the desguarar made the application.
+
+The PostTcType in each branch records the type the overload literal is
+found to have.
+
+\begin{code}
-- Comparison operations are needed when grouping literals
-- for compiling pattern-matching (module MatchLit)
instance Eq (HsOverLit id) where
- (HsIntegral i1 _ _) == (HsIntegral i2 _ _) = i1 == i2
- (HsFractional f1 _ _) == (HsFractional f2 _ _) = f1 == f2
- (HsIsString s1 _ _) == (HsIsString s2 _ _) = s1 == s2
- _ == _ = False
+ (OverLit {ol_val = val1}) == (OverLit {ol_val=val2}) = val1 == val2
+
+instance Eq OverLitVal where
+ (HsIntegral i1) == (HsIntegral i2) = i1 == i2
+ (HsFractional f1) == (HsFractional f2) = f1 == f2
+ (HsIsString s1) == (HsIsString s2) = s1 == s2
+ _ == _ = False
instance Ord (HsOverLit id) where
- compare (HsIntegral i1 _ _) (HsIntegral i2 _ _) = i1 `compare` i2
- compare (HsIntegral _ _ _) (HsFractional _ _ _) = LT
- compare (HsIntegral _ _ _) (HsIsString _ _ _) = LT
- compare (HsFractional f1 _ _) (HsFractional f2 _ _) = f1 `compare` f2
- compare (HsFractional _ _ _) (HsIntegral _ _ _) = GT
- compare (HsFractional _ _ _) (HsIsString _ _ _) = LT
- compare (HsIsString s1 _ _) (HsIsString s2 _ _) = s1 `compare` s2
- compare (HsIsString _ _ _) (HsIntegral _ _ _) = GT
- compare (HsIsString _ _ _) (HsFractional _ _ _) = GT
+ compare (OverLit {ol_val=val1}) (OverLit {ol_val=val2}) = val1 `compare` val2
+
+instance Ord OverLitVal where
+ compare (HsIntegral i1) (HsIntegral i2) = i1 `compare` i2
+ compare (HsIntegral _) (HsFractional _) = LT
+ compare (HsIntegral _) (HsIsString _) = LT
+ compare (HsFractional f1) (HsFractional f2) = f1 `compare` f2
+ compare (HsFractional _) (HsIntegral _) = GT
+ compare (HsFractional _) (HsIsString _) = LT
+ compare (HsIsString s1) (HsIsString s2) = s1 `compare` s2
+ compare (HsIsString _) (HsIntegral _) = GT
+ compare (HsIsString _) (HsFractional _) = GT
\end{code}
\begin{code}
ppr (HsStringPrim s) = pprHsString s <> char '#'
ppr (HsInt i) = integer i
ppr (HsInteger i _) = integer i
- ppr (HsRat f _) = rational f
- ppr (HsFloatPrim f) = rational f <> char '#'
- ppr (HsDoublePrim d) = rational d <> text "##"
+ ppr (HsRat f _) = ppr f
+ ppr (HsFloatPrim f) = ppr f <> char '#'
+ ppr (HsDoublePrim d) = ppr d <> text "##"
ppr (HsIntPrim i) = integer i <> char '#'
ppr (HsWordPrim w) = integer w <> text "##"
-- in debug mode, print the expression that it's resolved to, too
instance OutputableBndr id => Outputable (HsOverLit id) where
- ppr (HsIntegral i e _) = integer i <+> (ifPprDebug (parens (pprExpr e)))
- ppr (HsFractional f e _) = rational f <+> (ifPprDebug (parens (pprExpr e)))
- ppr (HsIsString s e _) = pprHsString s <+> (ifPprDebug (parens (pprExpr e)))
+ ppr (OverLit {ol_val=val, ol_witness=witness})
+ = ppr val <+> (ifPprDebug (parens (pprExpr witness)))
+
+instance Outputable OverLitVal where
+ ppr (HsIntegral i) = integer i
+ ppr (HsFractional f) = ppr f
+ ppr (HsIsString s) = pprHsString s
\end{code}
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