Happy is a YACC-like parse generator for Haskell
Happy is a yacc like parse generator for the haskell programming language.
Questions tagged [happy]
108 questions
2
votes
1 answer
Reference variable in quasiquoted LLVM
How do you pass a variable into a quasiquoted section?
I'm using llvm-quote-general and would like to pass a Type into an instruction I'm building with the quasiquoter.
I can build an instruction from just text:
alloci64 :: Instruction
alloci64 =…
Cirdec
- 24,019
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2
votes
2 answers
Parsing function application with Happy
How would I parse something like
f x y
Into
APPLY (APPLY f x) y
using Happy? Right now I have a rule that says
%left APP
Expr : Expr Expr %prec APP { APPLY $1 $2 }
But that parses the above as
APPLY f (APPLY x y)
spacepotato
- 173
- 7
2
votes
1 answer
Possible bug in Happy?
I am writing a parser using Happy/Alex, and because the grammar I am parsing isn't entirely context free, I have need to get a hold of the lookahead token. The Happy documentation suggests that when using a threaded lexer, this can be done with…
John G
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2
votes
1 answer
Happy resolution of an error
In Regular Expressions, I can write:
a(.)*b
And this will match the entire string in, for example
acdabb
I try to simulate this with a token stream in Happy.
t : a wildcard b
wildcard : {- empty -} | wild wildcard
wild : a | b | c | d |…
Jonathan Gallagher
- 2,115
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2
votes
1 answer
What is a Grammar Rule (in Parsing)?
I am trying to write an interpreter but am having difficulty understanding the theoretical underpinnings of the process.
I understand that the first part is to write a lexer which splits the string up into a list of valid tokens and then a parser is…
Anko
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2
votes
1 answer
noob wants make a parser for a small language
I want make a parser in happy for the let-in-expression language. For example, i want parse the following string:
let x = 4 in x*x
At the university we study attribute grammars, and i want use this tricks to calculate directly the value of the…
optimusfrenk
- 1,271
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2
votes
1 answer
How to Lex, Parse, and Serialize-to-XML Email Messages using Alex and Happy
I am working toward being able to input any email message and output an equivalent XML encoding.
I am starting small, with one of the email headers -- the "From Header"
Here is an example of a From Header:
From: John Doe
I want it…
Roger Costello
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2
votes
1 answer
Haskell - Happy, math expressions and variables parser
I'm working on a Happy math expressions and variables parser. The problem is that I don't know how to save the value for a variable and use it later. Any ideas?
This is how I recognize expressions and variables assignment:
genExp : exp …
John Smith
- 1,276
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2
votes
2 answers
Shift/Reduce conflicts in a propositional logic parser in Happy
I'm making a simple propositional logic parser on happy based on this BNF definition of the propositional logic grammar, this is my code
{
module FNC where
import Data.Char
import System.IO
}
-- Parser name, token types and error function…
Alan Dávalos
- 21
- 2
2
votes
2 answers
Shift reduce conflicts in happy grammar
Hello good programmers,
I have built following grammar in happy (haskell):
P : program C {Prog $2}
E : int {Num $1}
| ident {Id $1}
| true {BoolConst True}
| false {BoolConst…
user1422467
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- 2
2
votes
4 answers
How to make a Syntax Highlighting for Java in Haskell?
Soon enough I will be forced to present a project in Haskell that is supposed to make a Java syntax highlighting. I did some research and I found out that Happy could be a solution( since is a yacc-like parser). Also there were mentioned Bison and…
Antonio
- 35
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2
votes
1 answer
shift/reduce conflict in Happy
How can I make correct rules for parsing if-then[-else] case?
Here is some grammar:
{
module TestGram (tparse) where
}
%tokentype { String }
%token one { "1" }
if { "if" }
then { "then" }
else { "else" …
user1374768
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1
vote
2 answers
How do I match a Regular Expression in a Happy parser?
I'm writing a JavaScript parser with Happy and I need to match a regular expression. I don't want to fully parse the regex, just store it as a string.
The relevant part of my AST looks like this:
data PrimaryExpr
-- | Literal integer
=…
Nick Brunt
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1
vote
0 answers
Puzzling error message in Happy parser
I'm building a JavaScript parser in Haskell using Happy and I'm running into an error message that, no matter how hard I try, I can't debug.
I can't really post all the code here as it is thousands of lines long. I'll try to post the relevant bits…
Nick Brunt
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1
vote
0 answers
What is wrong with my "token type" in Happy?
I am writing a simple arithmetic expression parser in the Haskell platform's Happy. The Happy tutorial (labeled "Documentation") from the Haskell site implements a similar grammar to what I need. The difference is that I want to include floating…
nau5ea
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