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%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[HsLit]{Abstract syntax: source-language literals}
\begin{code}
module HsLit where
#include "HsVersions.h"
import {-# SOURCE #-} HsExpr( SyntaxExpr )
import Type ( Type )
import Outputable
import FastString
import Ratio ( Rational )
\end{code}
%************************************************************************
%* *
\subsection[HsLit]{Literals}
%* *
%************************************************************************
\begin{code}
data HsLit
= HsChar Char -- Character
| HsCharPrim Char -- Unboxed character
| HsString FastString -- String
| HsStringPrim FastString -- Packed string
| HsInt Integer -- Genuinely an Int; arises from TcGenDeriv,
-- and from TRANSLATION
| HsIntPrim Integer -- Unboxed Int
| 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
-- (overloaded literals are done with HsOverLit)
| HsFloatPrim Rational -- Unboxed Float
| HsDoublePrim Rational -- Unboxed Double
instance Eq HsLit where
(HsChar x1) == (HsChar x2) = x1==x2
(HsCharPrim x1) == (HsCharPrim x2) = x1==x2
(HsString x1) == (HsString x2) = x1==x2
(HsStringPrim x1) == (HsStringPrim x2) = x1==x2
(HsInt x1) == (HsInt x2) = x1==x2
(HsIntPrim x1) == (HsIntPrim x2) = x1==x2
(HsInteger x1 _) == (HsInteger x2 _) = x1==x2
(HsRat x1 _) == (HsRat x2 _) = x1==x2
(HsFloatPrim x1) == (HsFloatPrim x2) = x1==x2
(HsDoublePrim x1) == (HsDoublePrim x2) = x1==x2
lit1 == lit2 = False
data HsOverLit id -- An overloaded literal
= HsIntegral Integer (SyntaxExpr id) -- Integer-looking literals;
| HsFractional Rational (SyntaxExpr id) -- Frac-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
-- 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
l1 == l2 = False
instance Ord (HsOverLit id) where
compare (HsIntegral i1 _) (HsIntegral i2 _) = i1 `compare` i2
compare (HsIntegral _ _) (HsFractional _ _) = LT
compare (HsFractional f1 _) (HsFractional f2 _) = f1 `compare` f2
compare (HsFractional f1 _) (HsIntegral _ _) = GT
\end{code}
\begin{code}
instance Outputable HsLit where
-- Use "show" because it puts in appropriate escapes
ppr (HsChar c) = pprHsChar c
ppr (HsCharPrim c) = pprHsChar c <> char '#'
ppr (HsString s) = pprHsString s
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 (HsIntPrim i) = integer i <> char '#'
instance Outputable (HsOverLit id) where
ppr (HsIntegral i _) = integer i
ppr (HsFractional f _) = rational f
\end{code}
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