never executed always true always false

    1 {-# LANGUAGE QuasiQuotes #-}
    2 
    3 module Conjure.Rules.Vertical.MSet.Occurrence where
    4 
    5 import Conjure.Rules.Import
    6 
    7 
    8 rule_Comprehension :: Rule
    9 rule_Comprehension = "mset-comprehension{Occurrence}" `namedRuleZ` theRule where
   10     theRule z (Comprehension body gensOrConds) = do
   11         (gocBefore, (pat, s), gocAfter) <- matchFirst gensOrConds $ \ goc -> case goc of
   12             Generator (GenInExpr pat@Single{} s) -> return (pat, s)
   13             _ -> na "rule_Comprehension"
   14         TypeMSet{}             <- typeOf s
   15         MSet_Occurrence        <- representationOf s
   16         [m]                    <- downX1 s
   17         DomainMatrix index _   <- domainOf m
   18         let upd val old = lambdaToFunction pat old val
   19         theyDo <- doDuplicatesMatter z
   20         return
   21             ( "Vertical rule for mset-comprehension, Occurrence representation"
   22             , do
   23                 (jPat, j) <- quantifiedVar
   24                 let val = j
   25                 let outBody = upd val body
   26                 return $ Comprehension (if theyDo then [essence| &outBody * &m[&j] |]
   27                                                     else outBody)
   28                         $  gocBefore
   29                         ++ [ Generator (GenDomainNoRepr jPat index)
   30                             , Condition [essence| &m[&j] > 0 |]
   31                             ]
   32                         ++ transformBi (upd val) gocAfter
   33             )
   34     theRule _ _ = na "rule_Comprehension"
   35 
   36 
   37 rule_Freq :: Rule
   38 rule_Freq = "mset-freq{Occurrence}" `namedRule` theRule where
   39     theRule p = do
   40         (mset, x)              <- match opFreq p
   41         TypeMSet{}             <- typeOf mset
   42         MSet_Occurrence        <- representationOf mset
   43         [m]                    <- downX1 mset
   44         return
   45             ( "Vertical rule for mset-freq, Occurrence representation"
   46             , return [essence| &m[&x] |]
   47             )