Re: [Haskell-cafe] Operator precedence and associativity with Polyparse
Am 26.10.2011 01:49, schrieb Tom Hawkins: Can someone provide guidance on how handle operator precedence and associativity with Polyparse? Do you mean parsing something like 1 + 2 * 3 ? I don't think there's any real difference in using Polyparse vs Parsec for this, except for doing p `orElse` q rather than try p| q. Actually, I was looking for something equivalent to Text.ParserCombinators.Parsec.Expr.buildExpressionParser. I suppose I should learn how Parsec implements this under the hood. I would do it as described under chainl1 in http://hackage.haskell.org/packages/archive/parsec2/1.0.0/doc/html/Text-ParserCombinators-Parsec-Combinator.html I believe Parsec.Expr cannot handle a prefix operator (i.e. unary minus) properly, that has lower precedence than an infix operator (i.e. ^ power). If it can parse -x^2 as -(x^2) then if cannot parse x^ -2 as x^(-2). Cheers Christian -Tom ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence and associativity with Polyparse
On 26 October 2011 06:37, Tom Hawkins tomahawk...@gmail.com wrote: Hi, Can someone provide guidance on how handle operator precedence and associativity with Polyparse? Do you mean parsing something like 1 + 2 * 3 ? I don't think there's any real difference in using Polyparse vs Parsec for this, except for doing p `orElse` q rather than try p | q. -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence and associativity with Polyparse
Can someone provide guidance on how handle operator precedence and associativity with Polyparse? Do you mean parsing something like 1 + 2 * 3 ? I don't think there's any real difference in using Polyparse vs Parsec for this, except for doing p `orElse` q rather than try p | q. Actually, I was looking for something equivalent to Text.ParserCombinators.Parsec.Expr.buildExpressionParser. I suppose I should learn how Parsec implements this under the hood. -Tom ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence and associativity with Polyparse
On 26 October 2011 10:49, Tom Hawkins tomahawk...@gmail.com wrote: Can someone provide guidance on how handle operator precedence and associativity with Polyparse? Do you mean parsing something like 1 + 2 * 3 ? I don't think there's any real difference in using Polyparse vs Parsec for this, except for doing p `orElse` q rather than try p | q. Actually, I was looking for something equivalent to Text.ParserCombinators.Parsec.Expr.buildExpressionParser. I suppose I should learn how Parsec implements this under the hood. There's nothing like that for PolyParse: it has a much smaller set of combinators than Parsec, which I for one prefer because I don't have to worry about behaviour of existing combinators being different than what I want/need (as it stands, I already use a custom version of bracket from polyparse). -- Ivan Lazar Miljenovic ivan.miljeno...@gmail.com IvanMiljenovic.wordpress.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
Take a look to the Haskell Report: http://www.haskell.org/onlinereport/haskell2010/haskellch9.html#x16-1710009 -- Daniel Díaz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
Thanks, Daniel. This be all of them? Michael infixr 9 . infixr 8 ^, ^^, ⋆⋆ infixl 7 ⋆, /, ‘quot‘, ‘rem‘, ‘div‘, ‘mod‘ infixl 6 +, - -- The (:) operator is built-in syntax, and cannot legally be given -- a fixity declaration; but its fixity is given by: -- infixr 5 : infix 4 ==, /=, , =, =, infixr 3 infixr 2 || infixl 1 , = infixr 1 = infixr 0 $, $!, ‘seq‘ --- On Mon, 9/6/10, Daniel Díaz lazy.dd...@gmail.com wrote: From: Daniel Díaz lazy.dd...@gmail.com Subject: Re: [Haskell-cafe] Operator precedence To: michael rice nowg...@yahoo.com, haskell-cafe@haskell.org Date: Monday, September 6, 2010, 1:06 PM Take a look to the Haskell Report: http://www.haskell.org/onlinereport/haskell2010/haskellch9.html#x16-1710009 -- Daniel Díaz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
Those are all operators in Prelude. See a concrete library for their operator precedences. -- Daniel Díaz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
A concrete library? I'm playing around with Data.Bits. It has .. and .|. which I assume are functions (rather than operators) because I don't see and infix statement for them. Correct? Michael --- On Mon, 9/6/10, Daniel Díaz lazy.dd...@gmail.com wrote: From: Daniel Díaz lazy.dd...@gmail.com Subject: Re: [Haskell-cafe] Operator precedence To: michael rice nowg...@yahoo.com, haskell-cafe@haskell.org Date: Monday, September 6, 2010, 1:17 PM Those are all operators in Prelude. See a concrete library for their operator precedences. -- Daniel Díaz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
Hello michael, Monday, September 6, 2010, 9:00:32 PM, you wrote: Is there a handy list of operators and their precedence somewhere? unlike most languages, operators are user-definable in haskell. so there is no comprehensive list any function with two arguments van be used as operator: a `min` b any operator may be defined or used as a function: () a b = ... main = print (() True False) -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
On Mon, Sep 6, 2010 at 1:37 PM, michael rice nowg...@yahoo.com wrote: A concrete library? I'm playing around with Data.Bits. It has .. and .|. which I assume are functions (rather than operators) because I don't see and infix statement for them. Correct? .|. and .. are operators because they are made from symbol characters. Operators default to infixl 9 unless specified otherwise, so no infix declaration is needed. However, Data.Bits does have infix declarations for .. and .|. : infixl 8 `shift`, `rotate`, `shiftL`, `shiftR`, `rotateL`, `rotateR` infixl 7 .. infixl 6 `xor` infixl 5 .|. If you want to check the fixity of an operator, use :info in GHCi. Prelude Data.Bits :i .|. class (Num a) = Bits a where ... (.|.) :: a - a - a ... -- Defined in Data.Bits infixl 5 .|. -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
Hi David, You're right, I keep forgetting to look at the source code. And I wasn't aware of the info (:i) command. Should come in handy in the future. Michael --- On Mon, 9/6/10, David Menendez d...@zednenem.com wrote: From: David Menendez d...@zednenem.com Subject: Re: [Haskell-cafe] Operator precedence To: michael rice nowg...@yahoo.com Cc: haskell-cafe@haskell.org, Daniel Díaz lazy.dd...@gmail.com Date: Monday, September 6, 2010, 1:50 PM On Mon, Sep 6, 2010 at 1:37 PM, michael rice nowg...@yahoo.com wrote: A concrete library? I'm playing around with Data.Bits. It has .. and .|. which I assume are functions (rather than operators) because I don't see and infix statement for them. Correct? .|. and .. are operators because they are made from symbol characters. Operators default to infixl 9 unless specified otherwise, so no infix declaration is needed. However, Data.Bits does have infix declarations for .. and .|. : infixl 8 `shift`, `rotate`, `shiftL`, `shiftR`, `rotateL`, `rotateR` infixl 7 .. infixl 6 `xor` infixl 5 .|. If you want to check the fixity of an operator, use :info in GHCi. Prelude Data.Bits :i .|. class (Num a) = Bits a where ... (.|.) :: a - a - a ... -- Defined in Data.Bits infixl 5 .|. -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
El Lun, 6 de Septiembre de 2010, 7:50 pm, David Menendez escribió: Operators default to infixl 9 unless specified otherwise, so no infix declaration is needed. Why there is a default infix? Why it is 9? -- Daniel Díaz ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Operator precedence
On Mon, Sep 6, 2010 at 2:21 PM, Daniel Díaz danield...@asofilak.es wrote: El Lun, 6 de Septiembre de 2010, 7:50 pm, David Menendez escribió: Operators default to infixl 9 unless specified otherwise, so no infix declaration is needed. Why there is a default infix? Why it is 9? That's what the Haskell Report says: Any operator lacking a fixity declaration is assumed to be infixl 9 (section 4.4.2). Any function with at least two arguments can be used as an operator, so there has to be a default. Presumably, infixl 9 was considered the least surprising. -- Dave Menendez d...@zednenem.com http://www.eyrie.org/~zednenem/ ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
