Generator/Exponential: Difference between revisions
→{{header|C}}
SqrtNegInf (talk | contribs) m (→{{header|Raku}}: no need to reverse arguments to 'X**' operation) |
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{{Out}}
<pre>{529, 576, 625, 676, 784, 841, 900, 961, 1024, 1089}</pre>
=={{header|ATS}}==
<syntaxhighlight lang="ats">
(* "Generators" *)
(* I implement "generators" as non-linear closures. *)
#include "share/atspre_staload.hats"
staload UN = "prelude/SATS/unsafe.sats"
#define NIL list_nil ()
#define :: list_cons
(* Integer powers where base and power are of any unsigned integer
types. *)
fn {tk_b, tk_p : tkind}
g1uint_ipow
(base : g1uint tk_b,
power : g1uint tk_p)
:<> g1uint tk_b =
let
fun
loop {p : nat}
.<p>.
(b : g1uint tk_b,
p : g1uint (tk_p, p),
accum : g1uint tk_b)
:<> g1uint tk_b =
let
val ph = half p
val accum = (if ph + ph = p then accum else accum * b)
in
if ph = g1i2u 0 then
accum
else
loop (b * b, ph, accum)
end
prval () = lemma_g1uint_param base
prval () = lemma_g1uint_param power
in
loop (base, power, g1i2u 1)
end
overload ipow with g1uint_ipow of 100
(* Some unit tests of ipow. *)
val- 0U = ipow (0U, 100U)
val- 1U = ipow (0U, 0U) (* Sometimes a convenient result. *)
val- 9UL = ipow (3UL, 2ULL)
val- 81ULL = ipow (3ULL, 4U)
typedef generator (tk : tkind) =
() -<cloref1> g1uint tk
typedef option_generator (tk : tkind) =
() -<cloref1> Option (g1uint tk)
fn {tk_b : tkind}
{tk_p : tkind}
make_powers_generator
(power : g1uint tk_p)
:<!wrt> generator tk_b =
let
val base : ref (g1uint tk_b) = ref (g1i2u 0)
in
lam () =>
let
val b = !base
val result = ipow (b, power)
in
!base := succ b;
result
end
end
fn {tk : tkind}
make_generator_of_1_that_are_not_also_2
(gen1 : generator tk,
gen2 : generator tk)
:<!wrt> generator tk =
let
val initialized : ref bool = ref false
val x2 : ref (g1uint tk) = ref (g1i2u 0)
fn
check (x1 : g1uint tk)
:<1> bool =
let
fun
loop ()
:<1> bool =
if x1 <= !x2 then
(x1 <> !x2)
else
begin
!x2 := gen2 ();
loop ()
end
in
loop ()
end
in
lam () =>
let
var result : g1uint tk = g1i2u 0
var found_one : bool = false
in
if ~(!initialized) then
begin
!x2 := gen2 ();
!initialized := true
end;
while (~found_one)
let
val next1 = gen1 ()
in
if check next1 then
begin
result := next1;
found_one := true
end
end;
result
end
end
fn {tk : tkind}
make_dropper
(n : size_t,
gen : generator tk)
:<!wrt> generator tk =
let
val counter : ref size_t = ref n
in
lam () =>
begin
while (isneqz (!counter))
let
val _ = gen ()
in
!counter := pred (!counter)
end;
gen ()
end
end
fn {tk : tkind}
make_taker
(n : size_t,
gen : generator tk)
:<!wrt> option_generator tk =
let
val counter : ref size_t = ref n
in
lam () =>
if iseqz (!counter) then
None ()
else
begin
!counter := pred (!counter);
Some (gen ())
end
end
implement
main0 () =
let
stadef tk = uintknd
macdef filter = make_generator_of_1_that_are_not_also_2<tk>
val squares_generator = make_powers_generator<tk> 2U
val cubes_generator = make_powers_generator<tk> 3U
val gen = filter (squares_generator, cubes_generator)
val gen = make_dropper<tk> (i2sz 20, gen)
val gen = make_taker<tk> (i2sz 10, gen)
var done : bool = false
in
while (~done)
begin
case+ gen () of
| None () => done := true
| Some x => print! (" ", x)
end;
println! ()
end
</syntaxhighlight>
{{out}}
<pre>$ patscc -DATS_MEMALLOC_GCBDW generator-exponential.dats -lgc && ./a.out
529 576 625 676 784 841 900 961 1024 1089</pre>
=={{header|C}}==
| |||