(core) using index notation in fsyntax array example

Src-commit: 963ab68f8fb03b708a659442a0d5be41f60e38f1

Author: jfmc

core/library/fsyntax/examples/arrays_ops.pl

@@ -1,7 +1,9 @@
 :- use_package(functional).
 
-:- op(150,xfx,[@]).
-:- fun_eval '@'/2.
+% Postfix blocks enable X[I1,...In] syntax
+:- push_prolog_flag(read_postfix_blocks, on).
+:- op(40, yf, ['[]']). % (inside a list, otherwise the list is empty!)
+:- fun_eval abbrev('\6\postfix_block'(X,Idx), ~get_elem(X,Idx)). % (X[I1,...,In])
 
 :- op(500,yfx,<+>).
 :- fun_eval '<+>'/2.

core/library/fsyntax/examples/arrays_rt.pl

@@ -3,7 +3,7 @@
 :- include(arrays_ops).
 
 :- doc(title,"Some simple array operations with syntactic support").
-:- doc(author,"Pro Grammer").
+:- doc(author,"The Ciao Development Team").
 
 :- doc(module,"This library implements a very simple set of
    operations on arrays. The idea is to illustrate the use of
@@ -18,7 +18,7 @@
 %% :- doc(doinclude,vector/1).
 %% :- doc(doinclude,dim/1).
 
-:- regtype array(A) #"@var{A} is a multi-dimensional array.".
+:- regtype array(A) # "@var{A} is a multi-dimensional array.".
 % Should obviously be defined in more detail...
 array(A) :- struct(A).
 
@@ -46,11 +46,11 @@
     fixed_array(Ms,Arg),
     rows(N-1,Ms,A).
 
-:- pred @(Array,Index,Elem):: array * dim * int
+:- pred get_elem(Array,Index,Elem):: array * dim * int
 # "@var{Elem} is the @var{Index}-th element of @var{Array}.".
 
-V@[I]    := ~arg(I,V).
-V@[I|Js] := ~arg(I,V)@Js.
+get_elem(V,[])     := V.
+get_elem(V,[I|Js]) := ~get_elem(~arg(I,V),Js).
 
 :- pred <+>(V1,V2,V3) :: vector * vector * vector
 # "@var{V3} is @var{V1} + @var{V2}.".
@@ -64,7 +64,7 @@
 vecplus_(0,_,_,_).
 vecplus_(N,V1,V2,V3) :- 
     N > 0,
-    V3@[N] = V1@[N] + V2@[N],
+    V3[N] = V1[N] + V2[N],
     vecplus_(N-1,V1,V2,V3).
 
 :- pred <*>(V1,V2,V3) :: vector * vector * vector
@@ -77,4 +77,4 @@
 vecmul_(0,  _,  _, Acc, Acc).
 vecmul_(N, V1, V2, Acc, IP) :-
     N > 0,
-    vecmul_( N-1, V1, V2, Acc + ( V1@[N] * V2@[N] ), IP).
+    vecmul_( N-1, V1, V2, Acc + ( V1[N] * V2[N] ), IP).

core/library/fsyntax/examples/arrays_test.pl

@@ -7,5 +7,10 @@
     V1 = a(1,3,4,5),
     V2 = a(5,4,3,1),
     I = 1,
-    display(V2@[I+1]),
+    display(V2[I+1]), nl,
     M = V1 <*> ( V2 <+> V1 ).
+
+foo(M) :-
+    M = a(a(_,_),a(_,_)),
+    M[1,2] = a,
+    M[2,1] = a.

core/library/fsyntax/fsyntax_doc.pl

@@ -406,7 +406,7 @@
 simplicity arity limitations, solved in any case typically by further
 nesting with logarithmic access time). The following recursive
 definition defines the property @tt{fixed_array/2} and also the array
-access operator @tt{@@}:
+access predicate @tt{get_elem/3}:
 
 @begin{verbatim}
 fixed_array([N|Ms],A):-
@@ -422,27 +422,31 @@
     array(Ms,Arg),
     rows(N-1,Ms,A).
 
-:- pred @@(Array,Index,Elem) :: array * list(int) * int
+:- pred get_elem(Array,Index,Elem):: array * list(int) * int
    # \"@@var@{Elem@} is the @@var@{Index@}-th element of @@var@{Array@}.\".
 
-:- op(150, xfx, '@@').
-:- fun_eval (@@)/2.
-V@@[I]    := ~arg(I,V).       %% Or: V@@[] := V. 
-V@@[I|Js] := ~arg(I,V)@@Js.
+get_elem(V,[])     := V.
+get_elem(V,[I|Js]) := ~get_elem(~arg(I,V),Js).
 @end{verbatim}
 
-This allows writing, e.g., @tt{M = fixed_array([2,2]), M@@[2,1] = 3}
-(which could also be expressed as @tt{fixed_array([2,2])@@[2,1] = 3}),
+Rather than using @tt{get_elem/3} directly, we will use @tt{:-
+push_prolog_flag(read_postfix_blocks, on)} and @tt{fun_eval abbrev}
+(see @tt{array_ops.pl} later) to allow the more compact notation
+@tt{M[I1,...,In]} as an abbreviation for
+@tt{~get_elem(M,[I1,...,In])}.
+
+This allows writing, e.g., @tt{M = fixed_array([2,2]), M[2,1] = 3}
+(which could also be expressed as @tt{fixed_array([2,2])[2,1] = 3}),
 where the call to the @tt{fixed_array} property generates an empty @em{2
-x 2} array @em{M} and @tt{M@@[2,1] = 3} puts @em{3} in @em{M[2,1]}. 
+x 2} array @em{M} and @tt{M[2,1] = 3} puts @em{3} in @em{M[2,1]}. 
 This can be done in the top level:
 @begin{verbatim}
-?- M = ~fixed_array([2,2]), M@@[2,1] = 3.
+?- M = ~fixed_array([2,2]), M[2,1] = 3.
 @end{verbatim}
 @noindent
-provided the @tt{op} and @tt{function} declarations are 
+provided the @tt{op} and @tt{fun_eval} declarations are 
 loaded into the top level also. 
-Another example of use is: @tt{A3@@[N+1,M] = A1@@[N-1,M] + A2@@[N,M+2]}.
+Another example of use is: @tt{A3[N+1,M] = A1[N-1,M] + A2[N,M+2]}.
 
 Such functionality can be grouped into a @em{package} as follows. The
 package main file (@tt{arrays.pl}) might be: