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Implementation of the Jobs Puzzle in Curry

by Sebastian Fischer, January 2015

Verbal problem description

There are four people: Roberta, Thelma, Steve, and Pete.

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-- Simple solver for the n-queens problem in Curry.
--
-- A placement is represented as permutation of [1..n], each list
-- element represents the placement of a queen in the column
-- corresponding to its index.

import Integer ( abs )

-- Solutions are computed using a lazy generate-and-test approach:
-- candidate solutions are created lazily and admissible solutions

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-- Efficient solver for the n-queens problem in Curry.
--
-- A placement is represented as permutation of [1..n], each list
-- element represents the placement of a queen in the column
-- corresponding to its index.

-- The implementation uses a finite domain constraint solver which is
-- available in the Curry system PAKCS.
--
import CLPFD

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-- This snippet simulates naive dictionary passing for Curry type
-- classes using the explicit-sharing package for functional logic
-- programming in Haskell.
--
-- It defines a dictionary for the class
--
--   class Arb a where arb :: a
--
-- and a corresponding instance for the type Bool
--

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#include <iostream>
#include <string>
#include <re2/re2.h>

using namespace std;
using namespace re2;

int main(int argc, char* args[]) {
  // not syncing C++ and C I/O is faster with simple matchings
  ios_base::sync_with_stdio(false);

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diff --git a/bluetile.cabal b/bluetile.cabal
index 5ccc294..fd358e6 100644
--- a/bluetile.cabal
+++ b/bluetile.cabal
@@ -1,5 +1,5 @@
 Name:                bluetile
-Version:             0.5.3
+Version:             0.5.3.1
 homepage:            http://www.bluetile.org/
 synopsis:            full-featured tiling for the GNOME desktop environment

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{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeOperators #-}

import Data.Function ( fix )
import Data.MemoTrie        -- from package MemoTrie
import Data.MemoCombinators -- from package data-memocombinators

main :: IO ()
main =
  -- without caching

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{-# LANGUAGE TypeFamilies, TypeOperators, FlexibleContexts #-}

module GenericFoldableTraversable where

import Data.Monoid         ( Monoid, mappend, mempty )
import Data.Foldable       ( Foldable, foldMap )

import Control.Applicative ( Applicative, pure, (<*>) )
import Data.Traversable    ( Traversable, traverse )

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{- 

example from

    http://blog.downstairspeople.org/2010/06/14/a-brutal-introduction-to-arrows/

rewritten using Applicative instance from

    http://cdsmith.wordpress.com/2011/07/30/arrow-category-applicative-part-i/

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tyFun : Set -> Set -> Set;
tyFun A T = A -> T;

using (G:Vect Set n) {

  data Expr : Vect Set n -> Set -> Set where
    Var : (i:Fin n) -> Expr G (vlookup i G)
  | Val : T -> Expr G T
  | Lam : Expr (A::G) T -> Expr G (tyFun A T) -- using `A -> T` directly fails
  | App : Expr G (A -> T) -> Expr G A -> Expr G T