1/*  Part of Extended Libraries for SWI-Prolog
    2
    3    Author:        Edison Mera
    4    E-mail:        efmera@gmail.com
    5    WWW:           https://github.com/edisonm/xlibrary
    6    Copyright (C): 2014, Process Design Center, Breda, The Netherlands.
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(clambda, [op(201,xfx,+\)]).

   45:- reexport(library(compound_expand)).   46:- reexport(library(lambda)).   47:- use_module(library(apply)).   48:- use_module(library(lists)).   49:- use_module(library(occurs)).   50:- init_expansors.   51
   52% Next module will require the installation of lambda package, comment it out if
   53% you only want compiled lambda expressions:
   54
   55remove_hats(^(H, G1), G) -->
   56    [H],
   57    !,
   58    remove_hats(G1, G).
   59remove_hats(G, G) --> [].
   60
   61remove_hats(G1, G, EL) :-
   62    remove_hats(G1, G2, EL, T),
   63    '$expand':extend_arg_pos(G2, _, T, G, _).
   64
   65cgoal_args(G1, G, AL, EL) :-
   66    G1 =.. [F|Args],
   67    cgoal_args(F, Args, G, Fr, EL),
   68    term_variables(Fr, AL).
   69
   70cgoal_args(\,  [G1|EL],    G, [], EL) :- remove_hats(G1, G, EL).
   71cgoal_args(+\, [Fr,G1|EL], G, Fr, EL) :- remove_hats(G1, G, EL).
   72
   73singleton(T, Name=V) :-
   74    occurrences_of_var(V, T, 1),
   75    \+ atom_concat('_', _, Name).
   76
   77have_name(VarL, _=Value) :-
   78    member(Var, VarL),
   79    Var==Value, !.
   80
   81bind_name(Name=_, Name).
   82
   83check_singletons(Goal, Term) :-
   84    term_variables(Term, VarL),
   85    Term = h(_, _, A),
   86    ( nb_current('$variable_names', Bindings)
   87    ->true
   88    ; Bindings = []
   89    ),
   90    include(have_name(VarL), Bindings, VarN),
   91    include(singleton(Term), VarN, VarSN),
   92    ( VarSN \= []
   93    ->term_variables(A, VarAL),
   94      include(have_name(VarAL), Bindings, VarAN),
   95      intersection(VarAN, VarSN, VarIN),
   96      subtract(VarSN, VarAN, VarDN),
   97      ( VarIN \= []
   98      ->maplist(bind_name, VarIN, INames),
   99        print_message(warning, local_variables_outside(INames, Goal, Bindings))
  100      ; true
  101      ),
  102      ( VarDN \= []
  103      ->maplist(bind_name, VarDN, DNames),
  104        print_message(warning, unused_parameter(DNames, Goal, Bindings))
  105      ; true
  106      )
  107    ; true
  108    ).
  109
  110prolog:message(local_variables_outside(Names, Goal, Bindings)) -->
  111    [ 'Local variables ~w should not occur outside lambda expression: ~W'-[Names, Goal, [variable_names(Bindings)]] ].
  112
  113prolog:message(unused_parameter(Names, Goal, Bindings)) -->
  114    [ 'Unused parameters ~w in lambda expression: ~W'-[Names, Goal, [variable_names(Bindings)]] ].
  115
  116lambdaize_args(G, A1, M, VL, Ex, A) :-
  117    check_singletons(G, h(VL, Ex, A1)),
  118    ( ( Ex==[]
  119      ; '$member'(E1, Ex),
  120        '$member'(E2, VL),
  121        E1==E2
  122      )
  123    ->'$expand':wrap_meta_arguments(A1, M, VL, Ex, A)
  124    ; '$expand':remove_arg_pos(A1, _, M, VL, Ex, A, _)
  125    ).
  126
  127goal_expansion(G1, G) :-
  128    callable(G1),
  129    cgoal_args(G1, G2, AL, EL),
  130    '$current_source_module'(M),
  131    expand_goal(G2, G3),
  132    lambdaize_args(G1, G3, M, AL, EL, G4),
  133    % '$expand':wrap_meta_arguments(G2, M, AL, EL, G3), % Use this to debug
  134    G4 =.. [AuxName|VL],
  135    append(VL, EL, AV),
  136    G =.. [AuxName|AV]