Fix typo

Fix typo

# Teach Maple (through depends and eval) about our new binding forms.
# forall bind from 1st arg to 2nd arg.
# Ints,Sums,ints,sums bind from 2nd arg to 1st arg, and also from each element
#   of the 4th arg to the other elements on the left and to the 3rd arg.

`depends/forall` := proc(bvar, pred, x, $)
  depends(pred, x minus convert(bvar, 'set'))
end proc:

`depends/Ints` := proc(body, bvar, rng, loops, x, $)
  local xx, i;
  if depends(body, x minus {bvar}) then return true end if;
  xx := x; # don't remove bvar from xx!
  for i from nops(loops) to 1 by -1 do
    if depends(op([i,2],loops), xx) then return true end if;
    xx := xx minus {op([i,1],loops)};
  end do;
  depends(rng, xx)
end proc:
`depends/Sums` := eval(`depends/Ints`):
`depends/ints` := eval(`depends/Ints`):
`depends/sums` := eval(`depends/Ints`):

`eval/forall` := proc(e, eqs, $)
  local bvar, pred;
  bvar, pred := op(e);
  eval(op(0,e), eqs)(BindingTools:-generic_evalat(bvar, pred, eqs))
end proc:

`eval/Ints` := proc(e, eqs, $)
  local body, bvar, rng, loops, n, i;
  body, bvar, rng, loops := op(e);
  bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
  eval(op(0,e), eqs)(body, bvar,
                     BindingTools:-generic_evalatstar(rng, loops, eqs))
end proc:
`eval/Sums` := eval(`eval/Ints`):
`eval/ints` := eval(`eval/Ints`):
`eval/sums` := eval(`eval/Ints`):

`eval/Int` := proc(e, eqs, $)
  local body, bound, bvar;
  body, bound := op(1..2, e);
  if bound :: name then
    bound, body := BindingTools:-generic_evalat(bound, body, eqs);
  elif bound :: `=` then
    bvar := lhs(bound);
    bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
    bound := bvar = eval(rhs(bound), eqs);
  else
    body, bound := BindingTools:-generic_evalatstar(body, bound, eqs);
  end if;
  eval(op(0,e), eqs)(body, bound, op(eval([op(3..-1,e)], eqs)))
end proc:
`eval/Sum`     := eval(`eval/Int`):
`eval/Product` := eval(`eval/Int`):
`eval/int`     := eval(`eval/Int`):
`eval/sum`     := eval(`eval/Int`):
`eval/product` := eval(`eval/Int`):

#############################################################################

Loop := module ()
  option package;
  local intssums, enter_piecewise, piecewise_And, wrap,
        Binder, Stmt, t_binder, t_stmt, t_exp,
        ModuleLoad;
  export
     # These first few are smart constructors (for themselves):
         ints, sums,
     # while these are "proper functions"
         mk_HArray, genLoop, unproducts, unproduct,
         peel, split, graft, rebase;
  # these names are not assigned (and should not be).  But they are
  # used as global names, so document that here.
  global Ints, Sums, csgn;
  uses Hakaru, KB;

  t_binder := 'Binder(identical(product, Product, sum, Sum), t_kb)';
  t_stmt   := 'Stmt(anything, list, list)';
  t_exp    := '{Stmt(identical(exp), [], []),
                Stmt(identical(`^`), [anything], [])}';

  ints := proc() intssums('ints', 'int', _passed) end proc;
  sums := proc() intssums('sums', 'sum', _passed) end proc;

  intssums := proc(makes::name, make::name,
                   ee::anything, xx::name, rr::range, ll::list(name=range),
                   kb::t_kb:=empty, $)
    local t, x, e, r, l, kb1, w0, pp;
    t := `if`(make=int, HReal(open_bounds(rr)), HInt(closed_bounds(rr)));
    x, kb1 := genType(xx, mk_HArray(t, ll), kb);
    e := eval(ee, xx=x);
    if nops(ll) > 0 then
      kb1 := assert(size(x)=op([-1,2,2],ll)-op([-1,2,1],ll)+1, kb1);
    end if;
    e := simplify_assuming(e, kb1);
    r, l, kb1 := genLoop(rr, ll, kb, 'Integrand'(x,e));
    w0, pp := unproducts(e, x, l, kb1);
    if depends(w0, x) then
      'makes'(e, x, rr, ll)
    else
      if nops(l) > 0 then
        try pp := convert(pp, 'piecewise', op([1,1],l)); catch: end try
      end if;
      w0 * foldl(product, make(pp,x=r), op(l))
    end if
  end proc;

  mk_HArray := proc(t::t_type, loops::list(name=range), $)
    local res, i;
    res := t;
    for i in loops do res := HArray(res) end do;
    res
  end proc;

  genLoop := proc(e, loops::list(name=range), kb::t_kb)
    local kb1, rng, ind, do_subst, i;
    kb1 := kb;
    rng := table();
    ind := table();
    do_subst := e -> foldl(((e,eq) -> eval(e, op([lhs(eq),1],loops)=rhs(eq))),
                           e, entries(ind, 'pairs'));
    for i from nops(loops) to 1 by -1 do
      rng[i] := do_subst(op([i,2],loops));
      ind[i], kb1 := genType(op([i,1],loops), HInt(closed_bounds(rng[i])),
                               kb1, _rest);
    end do;
    do_subst(e), zip(`=`, [entries(ind, 'nolist')],
                          [entries(rng, 'nolist')]), kb1
  end proc;

  unproducts := proc(w, x::name, loops::list(name=range), kb::t_kb, $)
    local w0, pp, j, w1, w2, loop;
    w0 := 1;
    pp := w;
    for j from nops(loops) to 1 by -1 do
      w1, pp := op(unproduct(pp, x, op(j,loops), [], `*`, kb, kb));
      # separate out each of the factors in w1, as they might have different
      # variable dependencies, which can be exploited by other routines
      w2 := convert(w1, 'list', '`*`');
      for loop in [op(j+1..-1, loops)] do
        w2 := map((w -> product(eval(w, x=idx(x,lhs(loop))), loop)), w2);
      end do;
      w0 := w0 * `*`(op(w2));
      # w0 := w0 * foldl(product, w1, op(j+1..-1, loops));
    end do;
    w0, pp
  end proc;

  # Find [w1,pp] so that
  #   wrap(heap,w,mode,kb1,kb0)
  #   = w1*product(eval(pp,var=idx(var,lhs(loop))),loop)
  # making w1 depend on var as little as possible.
  # The flag "mode" should be `+` if "heap" contains an entry of the form
  # t_exp, or `*` otherwise.
  unproduct := proc(w, var::name, loop::(name=range),
                    heap::list, mode::identical(`*`,`+`),
                    kb1::t_kb, kb0::t_kb, $)
    local ind, res, dummy, kb, kbThen, i, w1, pp, s, r, x;
    if not depends(w, var) then
      return [wrap(heap, w, mode, kb1, kb0), 1]
    end if;
    ind := map2(op, 2, indets(w, Hakaru:-idx(identical(var), anything)));
    if nops(ind) = 1 then
      ind := op(ind);
      # Make sure ind contains no bound variables before lifting it!
      # So, check that "extract using indets" and "rename using eval" commute.
      # Also, make sure the indexing isn't guarded by a piecewise.
      s := indets(ind, 'name');
      s := map(proc(x,$) local y; `if`(depends(ind,x), x=y, NULL) end proc, s);
      if indets(eval(w, s), Hakaru:-idx(identical(var), anything))
                = {Hakaru:-idx(var, eval(ind, s))}
         and {} = indets(w, And('specfunc(piecewise)',
                                dependent({var} union map(lhs, s)))) then
        kb  := assert(lhs(loop)=ind, kb1); # BUG! bijectivity assumed!
        res := subs(Hakaru:-idx(var,ind) = Hakaru:-idx(var,lhs(loop)), w);
        res := wrap(heap, res, mode, kb, kb0);
        res := subs(Hakaru:-idx(var,lhs(loop))=dummy, res);
        if not depends(res, var) then
          return [1, subs(dummy=var, res)]
        end if
      end if
    end if;
    if w :: mode then
      res := map(unproduct, `if`(mode=`*`, list_of_mul(w,kb1), [op(w)]),
                 var, loop, heap, mode, kb1, kb0);
      return [`*`(op(map2(op,1,res))), `*`(op(map2(op,2,res)))]
    end if;
    if w :: 'specfunc(piecewise)' then
      kb := kb1;
      for i from 1 to nops(w) do
        if i :: even then
          kbThen := assert(    op(i-1,w) , kb);
          kb     := assert(Not(op(i-1,w)), kb);
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kbThen,kb0))
        elif i = nops(w) then
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kb    ,kb0))
        end if
      end do;
      return [`*`(entries(w1,'nolist')), `*`(entries(pp,'nolist'))]
    end if;
    if mode = `*` then
      if w :: (anything^freeof(var)) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(`^`, [], [op(2,w)])], `*`, kb1, kb0)
      elif w :: exp(anything) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(exp, [], [])], `+`, kb1, kb0)
      elif w :: (freeof(var)^anything) then
        return unproduct(op(2,w), var, loop,
                         [op(heap), Stmt(`^`, [op(1,w)], [])], `+`, kb1, kb0)
      end if
    end if;
    if mode = `+` and w :: `*` then
      s, r := selectremove(depends, w, var);
      if s :: `*` then
        # Nonlinear %1 (time to reread kiselyov-lifted?)
      else
        return unproduct(s, var, loop,
                         [op(heap), Stmt(`*`, [], [r])], `+`, kb1, kb0)
      end if
    end if;
    if w :: And(specfunc(`if`(mode = `*`, {product, Product}, {sum, Sum})),
                anyfunc(anything, name=range(freeof(var)))) then
      x, kb := genType(op([2,1],w),
                       HInt(Bound(`>=`,op([2,2,1],w)),
                            Bound(`<=`,op([2,2,2],w))),
                       kb1,
                       w, var, loop, heap);
      return unproduct(eval(op(1,w), op([2,1],w)=x), var, loop,
                       [op(heap), Binder(op(0,w), kb1)], mode, kb, kb0)
    end if;
    return [wrap(heap, w, mode, kb1, kb0), 1]
  end proc;

  enter_piecewise := proc(ee, kb0::t_kb, mode::identical(`*`,`+`), $)
    local e, kb, mo;
    e  := ee;
    kb := kb0;
    mo := mode();
    while e :: 'specfunc(piecewise)' and nops(e) = 3 do
      if op(3,e) = mo then
        kb := assert(op(1,e), kb);
        e := op(2,e);
      elif op(2,e) = mo then
        kb := assert(Not(op(1,e)), kb);
        e := op(3,e);
      else
        break;
      end if;
    end do;
    e, kb
  end proc;

  piecewise_And := proc(cond::list, th, el, $)
    if nops(cond) = 0 or th = el then
      th
    else
      piecewise(And(op(cond)), th, el)
    end if
  end proc;

  wrap := proc(heap::list, e1, mode1::identical(`*`,`+`),
               kb1::t_kb, kb0::t_kb, $)
    local e, kb, mode, i, entry, rest, var, new_rng, make,
       dom_spec, w, arrrgs;
    e    := e1;
    kb   := kb1;
    mode := mode1;
    for i from nops(heap) to 1 by -1 do
      entry := op(i,heap);
      if entry :: t_binder then
        if not (op(1,entry) in `if`(mode=`+`, {sum,Sum},
                                              {product,Product})) then
          print("Warning: heap mode inconsistency", heap, mode1)
        end if;
        e := simplify_assuming(e, op(2,entry));
        e, kb := enter_piecewise(e, kb, mode);
        rest := kb_subtract(kb, op(2,entry));
        new_rng, rest := selectremove(type, rest,
          {[identical(genType), name, specfunc(HInt)],
           [identical(genLet), name, anything]});
        if not (new_rng :: [list]) then
          error "kb_subtract should return exactly one gen*"
        end if;
        new_rng := op(new_rng);
        var     := op(2,new_rng);
        if op(1,new_rng) = genType then
          make    := op(1,entry);
          new_rng := range_of_HInt(op(3,new_rng));
        else # op(1,new_rng) = genLet
          make    := eval;
          new_rng := op(3,new_rng);
        end if;
        dom_spec, rest := selectremove(depends,
          map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest),
          var);
        (e, w) := selectremove(depends, convert(e, 'list', `*`), var);
        w := `*`(op(w));
        if mode = `*` and not (w = 1) then
          w := w ^ `if`(make=eval,eval,sum)
                       (piecewise_And(dom_spec, 1, 0), var=new_rng);
        end if;
        e := w * make(piecewise_And(dom_spec, `*`(op(e)), mode()), var=new_rng);
        kb := foldr(assert, op(2,entry), op(rest));
      elif entry :: t_stmt then
        # We evaluate arrrgs first, in case op(1,stmt) is an operation (such as
        # piecewise) that looks ahead at how many arguments it is passed before
        # they are evaluated.
        arrrgs := op(op(2,entry)), e, op(op(3,entry));
        e      := op(1,entry)(arrrgs);
        if entry :: t_exp then
          if mode <> `+` then
            print("Warning: heap mode inconsistency?", heap, mode1)
          end if;
          mode := `*`;
        end if
      else error "Malformed heap entry %1", entry end if
    end do;
    if mode <> `*` then
      print("Warning: heap mode inconsistency??", heap, mode1)
    end if;
    e, kb := enter_piecewise(e, kb, mode);
    rest := kb_subtract(kb, kb0);
    rest := map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest);
    piecewise_And(rest,e,mode())
  end proc;

  # Rewrite product(piecewise(i=lo,th,el),i=lo..hi)
  # to eval(th,i=lo)*product(el,i=lo+1..hi)
  peel := proc(ee, $)
    evalindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(And(specfunc(piecewise),
                                    patfunc(name=anything,anything,anything)),
                                name=range))',
    proc(e, $)
      local body, x, r, make, rest;
      body := op(1,e);
      x, r := op(op(2,e));
      if op([1,1],body)=x and not depends(op([1,2],body),x) then
        if op(0,e) in {sum,Sum} then
          make := `+`;
        elif op(0,e) in {product,Product} then
          make := `*`;
        end if;
        if nops(body)=2 then
          rest := 0;
        elif nops(body)=3 then
          rest := op(3,body);
        else
          rest := subsop(1=NULL,2=NULL,body);
        end if;
        if op([1,2],body)=lhs(r) then
          return make(eval(op(2,body),x=lhs(r)),
                      subsop(1=rest, [2,2,1]=lhs(r)+1, e));
        elif op([1,2],body)=rhs(r) then
          return make(eval(op(2,body),x=rhs(r)),
                      subsop(1=rest, [2,2,2]=rhs(r)-1, e));
        end if
      end if;
      e
    end proc);
  end proc:

  # Expand sum(a*(b-c),q) to sum(a*b,q)-sum(a*c,q)
  split := proc(ee, $)
    evalindets(ee, 'And(specfunc({sum,Sum}),
                        anyfunc(And(`*`,Not(`*`(Not(`+`)))),name=anything))',
    proc(e, $)
      local terms, x;
      terms := convert(expand(op(1,e), op(indets(op(1,e), function))),
                       'list', `+`);
      x := op([2,1],e);
      `+`(op(map(proc(term, $)
        local s, r;
        s, r := selectremove(depends, convert(term, 'list', `*`), x);
        `*`(op(r), subsop(1=`*`(op(s)),e))
      end proc, terms)))
    end proc)
  end proc:

  # Simplify f(lo-1)*product(f(i),i=lo..hi) to product(f(i),i=lo-1..hi)
  graft := proc(ee, $)
    evalindets(ee, 'Or(And(`*`,Not(`*`(Not(specfunc({product,Product}))))),
                       And(`+`,Not(`+`(Not(specfunc({sum    ,Sum    }))))))',
    proc(e, $)
      local produce, factors, i, j;
      produce := `if`(e::`*`, '{product,Product}',
                              '{sum    ,Sum    }');
      factors := sort(convert(e,'list'),
                      key = (factor -> -numboccur(factor,produce)));
      for i from nops(factors) to 2 by -1 do
        for j from i-1 to 1 by -1 do
          if op(j,factors) :: 'And'('specfunc'(produce),
                                    'anyfunc(anything,name=range)') then
            if Testzero(op(i,factors) - eval(op([j,1],factors),
                 op([j,2,1],factors)=op([j,2,2,1],factors)-1)) then
              factors := subsop(i=NULL,applyop(`-`,[j,2,2,1],factors,1))
            elif Testzero(op(i,factors) - eval(op([j,1],factors),
                   op([j,2,1],factors)=op([j,2,2,2],factors)+1)) then
              factors := subsop(i=NULL,applyop(`+`,[j,2,2,2],factors,1))
            end if
          end if
        end do
      end do;
      op(0,e)(op(factors))
    end proc)
  end proc:

  # Normalize sum(f(i),i=2..hi) to sum(f(i+2),i=0..hi-2)
  rebase := proc(ee, $)
    evalindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(anything,name=Or(posint,negint)..anything))',
    proc(e, $)
      subsop([2,2,1]=0,
             applyop(`-`,
                     [2,2,2],
                     applyop(eval, 1, e, op([2,1],e)=op([2,1],e)+op([2,2,1],e)),
                     op([2,2,1],e)))
    end proc)
  end proc:

  ModuleLoad := proc($)
    # Override csgn to work a little bit harder on piecewise and sum
    # (to get rid of csgn(1/2+1/2*sum(piecewise(...,1,0),...))
    #  produced by int on a Gaussian mixture model)
    unprotect(csgn);
    csgn := overload([
      # Handle if the csgn of a piecewise doesn't depend on which branch
      proc(a :: specfunc(piecewise), $)
        option overload;
        local r, i;
        r := {seq(`if`(i::even or i=nops(a), csgn(op(i,a)), NULL),
                  i=1..nops(a))};
        if nops(r)=1 then return op(r) end if;
        if not assigned(_Envsignum0) then
          r := r minus {0};
          if nops(r)=1 then return op(r) end if;
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      # Handle if the csgn of a sum doesn't depend on the bound variable
      proc(a :: And(specfunc({sum, Sum}), anyfunc(anything, name=range)), $)
        option overload;
        local r;
        r := csgn(op(1,a));
        if not depends(r,op([2,1],a)) then
          return signum(op([2,2,2],a)+1-op([2,2,1],a)) * r
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      csgn]);
    protect(csgn);
  end proc;

  ModuleLoad();

end module; # Loop

# Teach Maple (through depends and eval) about our new binding forms.
# forall bind from 1st arg to 2nd arg.
# Ints,Sums,ints,sums bind from 2nd arg to 1st arg, and also from each element
#   of the 4th arg to the other elements on the left and to the 3rd arg.

`depends/forall` := proc(bvar, pred, x, $)
  depends(pred, x minus convert(bvar, 'set'))
end proc:

`depends/Ints` := proc(body, bvar, rng, loops, x, $)
  local xx, i;
  if depends(body, x minus {bvar}) then return true end if;
  xx := x; # don't remove bvar from xx!
  for i from nops(loops) to 1 by -1 do
    if depends(op([i,2],loops), xx) then return true end if;
    xx := xx minus {op([i,1],loops)};
  end do;
  depends(rng, xx)
end proc:
`depends/Sums` := eval(`depends/Ints`):
`depends/ints` := eval(`depends/Ints`):
`depends/sums` := eval(`depends/Ints`):

`eval/forall` := proc(e, eqs, $)
  local bvar, pred;
  bvar, pred := op(e);
  eval(op(0,e), eqs)(BindingTools:-generic_evalat(bvar, pred, eqs))
end proc:

`eval/Ints` := proc(e, eqs, $)
  local body, bvar, rng, loops, n, i;
  body, bvar, rng, loops := op(e);
  bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
  eval(op(0,e), eqs)(body, bvar,
                     BindingTools:-generic_evalatstar(rng, loops, eqs))
end proc:
`eval/Sums` := eval(`eval/Ints`):
`eval/ints` := eval(`eval/Ints`):
`eval/sums` := eval(`eval/Ints`):

`eval/Int` := proc(e, eqs, $)
  local body, bound, bvar;
  body, bound := op(1..2, e);
  if bound :: name then
    bound, body := BindingTools:-generic_evalat(bound, body, eqs);
  elif bound :: `=` then
    bvar := lhs(bound);
    bvar, body := BindingTools:-generic_evalat(bvar, body, eqs);
    bound := bvar = eval(rhs(bound), eqs);
  else
    body, bound := BindingTools:-generic_evalatstar(body, bound, eqs);
  end if;
  eval(op(0,e), eqs)(body, bound, op(eval([op(3..-1,e)], eqs)))
end proc:
`eval/Sum`     := eval(`eval/Int`):
`eval/Product` := eval(`eval/Int`):
`eval/int`     := eval(`eval/Int`):
`eval/sum`     := eval(`eval/Int`):
`eval/product` := eval(`eval/Int`):

#############################################################################

Loop := module ()
  option package;
  local intssums, enter_piecewise, piecewise_And, wrap,
        Binder, Stmt, t_binder, t_stmt, t_exp,
        ModuleLoad;
  export
     # These first few are smart constructors (for themselves):
         ints, sums,
     # while these are "proper functions"
         mk_HArray, genLoop, unproducts, unproduct,
         peel, split, graft, rebase;
  # these names are not assigned (and should not be).  But they are
  # used as global names, so document that here.
  global Ints, Sums, csgn;
  uses Hakaru, KB;

  t_binder := 'Binder(identical(product, Product, sum, Sum), t_kb)';
  t_stmt   := 'Stmt(anything, list, list)';
  t_exp    := '{Stmt(identical(exp), [], []),
                Stmt(identical(`^`), [anything], [])}';

  ints := proc() intssums('ints', 'int', _passed) end proc;
  sums := proc() intssums('sums', 'sum', _passed) end proc;

  intssums := proc(makes::name, make::name,
                   ee::anything, xx::name, rr::range, ll::list(name=range),
                   kb::t_kb:=empty, $)
    local t, x, e, r, l, kb1, w0, pp;
    t := `if`(make=int, HReal(open_bounds(rr)), HInt(closed_bounds(rr)));
    x, kb1 := genType(xx, mk_HArray(t, ll), kb);
    e := eval(ee, xx=x);
    if nops(ll) > 0 then
      kb1 := assert(size(x)=op([-1,2,2],ll)-op([-1,2,1],ll)+1, kb1);
    end if;
    e := simplify_assuming(e, kb1);
    r, l, kb1 := genLoop(rr, ll, kb, 'Integrand'(x,e));
    w0, pp := unproducts(e, x, l, kb1);
    if depends(w0, x) then
      'makes'(e, x, rr, ll)
    else
      if nops(l) > 0 then
        try pp := convert(pp, 'piecewise', op([1,1],l)); catch: end try
      end if;
      w0 * foldl(product, make(pp,x=r), op(l))
    end if
  end proc;

  mk_HArray := proc(t::t_type, loops::list(name=range), $)
    local res, i;
    res := t;
    for i in loops do res := HArray(res) end do;
    res
  end proc;

  genLoop := proc(e, loops::list(name=range), kb::t_kb)
    local kb1, rng, ind, do_subst, i;
    kb1 := kb;
    rng := table();
    ind := table();
    do_subst := e -> foldl(((e,eq) -> eval(e, op([lhs(eq),1],loops)=rhs(eq))),
                           e, entries(ind, 'pairs'));
    for i from nops(loops) to 1 by -1 do
      rng[i] := do_subst(op([i,2],loops));
      ind[i], kb1 := genType(op([i,1],loops), HInt(closed_bounds(rng[i])),
                               kb1, _rest);
    end do;
    do_subst(e), zip(`=`, [entries(ind, 'nolist')],
                          [entries(rng, 'nolist')]), kb1
  end proc;

  unproducts := proc(w, x::name, loops::list(name=range), kb::t_kb, $)
    local w0, pp, j, w1, w2, loop;
    w0 := 1;
    pp := w;
    for j from nops(loops) to 1 by -1 do
      w1, pp := op(unproduct(pp, x, op(j,loops), [], `*`, kb, kb));
      # separate out each of the factors in w1, as they might have different
      # variable dependencies, which can be exploited by other routines
      w2 := convert(w1, 'list', '`*`');
      for loop in [op(j+1..-1, loops)] do
        w2 := map((w -> product(eval(w, x=idx(x,lhs(loop))), loop)), w2);
      end do;
      w0 := w0 * `*`(op(w2));
      # w0 := w0 * foldl(product, w1, op(j+1..-1, loops));
    end do;
    w0, pp
  end proc;

  # Find [w1,pp] so that
  #   wrap(heap,w,mode,kb1,kb0)
  #   = w1*product(eval(pp,var=idx(var,lhs(loop))),loop)
  # making w1 depend on var as little as possible.
  # The flag "mode" should be `+` if "heap" contains an entry of the form
  # t_exp, or `*` otherwise.
  unproduct := proc(w, var::name, loop::(name=range),
                    heap::list, mode::identical(`*`,`+`),
                    kb1::t_kb, kb0::t_kb, $)
    local ind, res, dummy, kb, kbThen, i, w1, pp, s, r, x;
    if not depends(w, var) then
      return [wrap(heap, w, mode, kb1, kb0), 1]
    end if;
    ind := map2(op, 2, indets(w, Hakaru:-idx(identical(var), anything)));
    if nops(ind) = 1 then
      ind := op(ind);
      # Make sure ind contains no bound variables before lifting it!
      # So, check that "extract using indets" and "rename using eval" commute.
      # Also, make sure the indexing isn't guarded by a piecewise.
      s := indets(ind, 'name');
      s := map(proc(x,$) local y; `if`(depends(ind,x), x=y, NULL) end proc, s);
      if indets(eval(w, s), Hakaru:-idx(identical(var), anything))
                = {Hakaru:-idx(var, eval(ind, s))} and
         and {} = indets(w, And('specfunc(piecewise)',
                                dependent({var} union map(lhs, s)))) then
        kb  := assert(lhs(loop)=ind, kb1); # BUG! bijectivity assumed!
        res := subs(Hakaru:-idx(var,ind) = Hakaru:-idx(var,lhs(loop)), w);
        res := wrap(heap, res, mode, kb, kb0);
        res := subs(Hakaru:-idx(var,lhs(loop))=dummy, res);
        if not depends(res, var) then
          return [1, subs(dummy=var, res)]
        end if
      end if
    end if;
    if w :: mode then
      res := map(unproduct, `if`(mode=`*`, list_of_mul(w,kb1), [op(w)]),
                 var, loop, heap, mode, kb1, kb0);
      return [`*`(op(map2(op,1,res))), `*`(op(map2(op,2,res)))]
    end if;
    if w :: 'specfunc(piecewise)' then
      kb := kb1;
      for i from 1 to nops(w) do
        if i :: even then
          kbThen := assert(    op(i-1,w) , kb);
          kb     := assert(Not(op(i-1,w)), kb);
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kbThen,kb0))
        elif i = nops(w) then
          w1[i], pp[i] := op(unproduct(op(i,w),var,loop,heap,mode,kb    ,kb0))
        end if
      end do;
      return [`*`(entries(w1,'nolist')), `*`(entries(pp,'nolist'))]
    end if;
    if mode = `*` then
      if w :: (anything^freeof(var)) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(`^`, [], [op(2,w)])], `*`, kb1, kb0)
      elif w :: exp(anything) then
        return unproduct(op(1,w), var, loop,
                         [op(heap), Stmt(exp, [], [])], `+`, kb1, kb0)
      elif w :: (freeof(var)^anything) then
        return unproduct(op(2,w), var, loop,
                         [op(heap), Stmt(`^`, [op(1,w)], [])], `+`, kb1, kb0)
      end if
    end if;
    if mode = `+` and w :: `*` then
      s, r := selectremove(depends, w, var);
      if s :: `*` then
        # Nonlinear %1 (time to reread kiselyov-lifted?)
      else
        return unproduct(s, var, loop,
                         [op(heap), Stmt(`*`, [], [r])], `+`, kb1, kb0)
      end if
    end if;
    if w :: And(specfunc(`if`(mode = `*`, {product, Product}, {sum, Sum})),
                anyfunc(anything, name=range(freeof(var)))) then
      x, kb := genType(op([2,1],w),
                       HInt(Bound(`>=`,op([2,2,1],w)),
                            Bound(`<=`,op([2,2,2],w))),
                       kb1,
                       w, var, loop, heap);
      return unproduct(eval(op(1,w), op([2,1],w)=x), var, loop,
                       [op(heap), Binder(op(0,w), kb1)], mode, kb, kb0)
    end if;
    return [wrap(heap, w, mode, kb1, kb0), 1]
  end proc;

  enter_piecewise := proc(ee, kb0::t_kb, mode::identical(`*`,`+`), $)
    local e, kb, mo;
    e  := ee;
    kb := kb0;
    mo := mode();
    while e :: 'specfunc(piecewise)' and nops(e) = 3 do
      if op(3,e) = mo then
        kb := assert(op(1,e), kb);
        e := op(2,e);
      elif op(2,e) = mo then
        kb := assert(Not(op(1,e)), kb);
        e := op(3,e);
      else
        break;
      end if;
    end do;
    e, kb
  end proc;

  piecewise_And := proc(cond::list, th, el, $)
    if nops(cond) = 0 or th = el then
      th
    else
      piecewise(And(op(cond)), th, el)
    end if
  end proc;

  wrap := proc(heap::list, e1, mode1::identical(`*`,`+`),
               kb1::t_kb, kb0::t_kb, $)
    local e, kb, mode, i, entry, rest, var, new_rng, make,
       dom_spec, w, arrrgs;
    e    := e1;
    kb   := kb1;
    mode := mode1;
    for i from nops(heap) to 1 by -1 do
      entry := op(i,heap);
      if entry :: t_binder then
        if not (op(1,entry) in `if`(mode=`+`, {sum,Sum},
                                              {product,Product})) then
          print("Warning: heap mode inconsistency", heap, mode1)
        end if;
        e := simplify_assuming(e, op(2,entry));
        e, kb := enter_piecewise(e, kb, mode);
        rest := kb_subtract(kb, op(2,entry));
        new_rng, rest := selectremove(type, rest,
          {[identical(genType), name, specfunc(HInt)],
           [identical(genLet), name, anything]});
        if not (new_rng :: [list]) then
          error "kb_subtract should return exactly one gen*"
        end if;
        new_rng := op(new_rng);
        var     := op(2,new_rng);
        if op(1,new_rng) = genType then
          make    := op(1,entry);
          new_rng := range_of_HInt(op(3,new_rng));
        else # op(1,new_rng) = genLet
          make    := eval;
          new_rng := op(3,new_rng);
        end if;
        dom_spec, rest := selectremove(depends,
          map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest),
          var);
        (e, w) := selectremove(depends, convert(e, 'list', `*`), var);
        w := `*`(op(w));
        if mode = `*` and not (w = 1) then
          w := w ^ `if`(make=eval,eval,sum)
                       (piecewise_And(dom_spec, 1, 0), var=new_rng);
        end if;
        e := w * make(piecewise_And(dom_spec, `*`(op(e)), mode()), var=new_rng);
        kb := foldr(assert, op(2,entry), op(rest));
      elif entry :: t_stmt then
        # We evaluate arrrgs first, in case op(1,stmt) is an operation (such as
        # piecewise) that looks ahead at how many arguments it is passed before
        # they are evaluated.
        arrrgs := op(op(2,entry)), e, op(op(3,entry));
        e      := op(1,entry)(arrrgs);
        if entry :: t_exp then
          if mode <> `+` then
            print("Warning: heap mode inconsistency?", heap, mode1)
          end if;
          mode := `*`;
        end if
      else error "Malformed heap entry %1", entry end if
    end do;
    if mode <> `*` then
      print("Warning: heap mode inconsistency??", heap, mode1)
    end if;
    e, kb := enter_piecewise(e, kb, mode);
    rest := kb_subtract(kb, kb0);
    rest := map(proc(a::[identical(assert),anything],$) op(2,a) end proc, rest);
    piecewise_And(rest,e,mode())
  end proc;

  # Rewrite product(piecewise(i=lo,th,el),i=lo..hi)
  # to eval(th,i=lo)*product(el,i=lo+1..hi)
  peel := proc(ee, $)
    evalindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(And(specfunc(piecewise),
                                    patfunc(name=anything,anything,anything)),
                                name=range))',
    proc(e, $)
      local body, x, r, make, rest;
      body := op(1,e);
      x, r := op(op(2,e));
      if op([1,1],body)=x and not depends(op([1,2],body),x) then
        if op(0,e) in {sum,Sum} then
          make := `+`;
        elif op(0,e) in {product,Product} then
          make := `*`;
        end if;
        if nops(body)=2 then
          rest := 0;
        elif nops(body)=3 then
          rest := op(3,body);
        else
          rest := subsop(1=NULL,2=NULL,body);
        end if;
        if op([1,2],body)=lhs(r) then
          return make(eval(op(2,body),x=lhs(r)),
                      subsop(1=rest, [2,2,1]=lhs(r)+1, e));
        elif op([1,2],body)=rhs(r) then
          return make(eval(op(2,body),x=rhs(r)),
                      subsop(1=rest, [2,2,2]=rhs(r)-1, e));
        end if
      end if;
      e
    end proc);
  end proc:

  # Expand sum(a*(b-c),q) to sum(a*b,q)-sum(a*c,q)
  split := proc(ee, $)
    evalindets(ee, 'And(specfunc({sum,Sum}),
                        anyfunc(And(`*`,Not(`*`(Not(`+`)))),name=anything))',
    proc(e, $)
      local terms, x;
      terms := convert(expand(op(1,e), op(indets(op(1,e), function))),
                       'list', `+`);
      x := op([2,1],e);
      `+`(op(map(proc(term, $)
        local s, r;
        s, r := selectremove(depends, convert(term, 'list', `*`), x);
        `*`(op(r), subsop(1=`*`(op(s)),e))
      end proc, terms)))
    end proc)
  end proc:

  # Simplify f(lo-1)*product(f(i),i=lo..hi) to product(f(i),i=lo-1..hi)
  graft := proc(ee, $)
    evalindets(ee, 'Or(And(`*`,Not(`*`(Not(specfunc({product,Product}))))),
                       And(`+`,Not(`+`(Not(specfunc({sum    ,Sum    }))))))',
    proc(e, $)
      local produce, factors, i, j;
      produce := `if`(e::`*`, '{product,Product}',
                              '{sum    ,Sum    }');
      factors := sort(convert(e,'list'),
                      key = (factor -> -numboccur(factor,produce)));
      for i from nops(factors) to 2 by -1 do
        for j from i-1 to 1 by -1 do
          if op(j,factors) :: 'And'('specfunc'(produce),
                                    'anyfunc(anything,name=range)') then
            if Testzero(op(i,factors) - eval(op([j,1],factors),
                 op([j,2,1],factors)=op([j,2,2,1],factors)-1)) then
              factors := subsop(i=NULL,applyop(`-`,[j,2,2,1],factors,1))
            elif Testzero(op(i,factors) - eval(op([j,1],factors),
                   op([j,2,1],factors)=op([j,2,2,2],factors)+1)) then
              factors := subsop(i=NULL,applyop(`+`,[j,2,2,2],factors,1))
            end if
          end if
        end do
      end do;
      op(0,e)(op(factors))
    end proc)
  end proc:

  # Normalize sum(f(i),i=2..hi) to sum(f(i+2),i=0..hi-2)
  rebase := proc(ee, $)
    evalindets(ee, 'And(specfunc({sum,Sum,product,Product}),
                        anyfunc(anything,name=Or(posint,negint)..anything))',
    proc(e, $)
      subsop([2,2,1]=0,
             applyop(`-`,
                     [2,2,2],
                     applyop(eval, 1, e, op([2,1],e)=op([2,1],e)+op([2,2,1],e)),
                     op([2,2,1],e)))
    end proc)
  end proc:

  ModuleLoad := proc($)
    # Override csgn to work a little bit harder on piecewise and sum
    # (to get rid of csgn(1/2+1/2*sum(piecewise(...,1,0),...))
    #  produced by int on a Gaussian mixture model)
    unprotect(csgn);
    csgn := overload([
      # Handle if the csgn of a piecewise doesn't depend on which branch
      proc(a :: specfunc(piecewise), $)
        option overload;
        local r, i;
        r := {seq(`if`(i::even or i=nops(a), csgn(op(i,a)), NULL),
                  i=1..nops(a))};
        if nops(r)=1 then return op(r) end if;
        if not assigned(_Envsignum0) then
          r := r minus {0};
          if nops(r)=1 then return op(r) end if;
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      # Handle if the csgn of a sum doesn't depend on the bound variable
      proc(a :: And(specfunc({sum, Sum}), anyfunc(anything, name=range)), $)
        option overload;
        local r;
        r := csgn(op(1,a));
        if not depends(r,op([2,1],a)) then
          return signum(op([2,2,2],a)+1-op([2,2,1],a)) * r
        end if;
        error "invalid input: cannot csgn %1", a;
      end proc,
      csgn]);
    protect(csgn);
  end proc;

  ModuleLoad();

end module; # Loop


More general interface to RoundTrip

More general interface to RoundTrip

# This module forms part of NewSLO and is `$include`d there

RoundTrip := proc(e, t::t_type, {_ret_type := {'print'}})
  local result, ret_type; ret_type := _ret_type;
  if not(ret_type::set) then ret_type := {ret_type}; end if;

  interface(screenwidth=9999, prettyprint=0, warnlevel=0,
    showassumed=0,quiet=true);
  kernelopts(assertlevel=0);
  result := eval(ToInert(Simplify(e,t,_rest)), _Inert_ATTRIBUTE=NULL);
  result := sprintf("%a",result);
  if 'print' in ret_type then printf("%s\n",result); end if;
  if 'string' in ret_type then
    result;
  else
    NULL;
  end if;
end proc;

Simplify := proc(e, t::t_type, {ctx :: list := []}, $)
  subsindets(SimplifyKB(e, t, build_kb(ctx, "Simplify")),
             And({t_sum, t_product}, anyfunc(anything, anything=range)),
             e -> subsop(0 = `if`(e::t_sum, SumIE, ProductIE),
                         applyop(`+`, [2,2,2], e, 1)))
end proc;

SimplifyKB_ := proc(leaf, e, t::t_type, kb::t_kb, $)
  local patterns, x, kb1, ex;
  if t :: HFunction(anything, anything) then
    patterns := htype_patterns(op(1,t));
    if patterns :: Branches(Branch(PVar(name),anything)) then
      # Eta-expand the function type
      x := `if`(e::lam(name,anything,anything), op(1,e),
                op([1,1,1],patterns));
      x, kb1 := genType(x, op(1,t), kb, e);
      ex := app(e,x);
      lam(x, op(1,t), SimplifyKB_(leaf,ex, op(2,t), kb1))
    else
      # Eta-expand the function type and the sum-of-product argument-type
      x := `if`(e::lam(name,anything,anything), op(1,e), d);
      if depends([e,t,kb], x) then x := gensym(x) end if;
      ex := app(e,x);
      lam(x, op(1,t), 'case'(x,
        map(proc(branch)
            local eSubst, pSubst, p1, binds, y, kb1, i, pSubst1;
              eSubst, pSubst := pattern_match([x,e], x, op(1,branch));
              p1 := subs(pSubst, op(1,branch));
              binds := [pattern_binds(p1)];
              kb1 := kb;
              pSubst1 := table();
              for i from 1 to nops(binds) do
                y, kb1 := genType(op(i,binds), op([2,i],branch), kb1);
                pSubst1[op(i,binds)] := y;
              end do;
              pSubst1 := op(op(pSubst1));
              Branch(subs(pSubst1, p1),
                     SimplifyKB_(leaf,eval(eval(ex,eSubst),pSubst1), op(2,t), kb1))
            end proc,
            patterns)))
    end if
  else
    leaf(e,t,kb)
  end if
end proc;

SimplifyKB := curry(SimplifyKB_,
  proc(e0,t,kb)
    local e := eval_for_Simplify(e0,kb);
    if t :: HMeasure(anything) then
      fromLO(improve(toLO(e), _ctx=kb), _ctx=kb);
    else
      simplify_assuming(e,kb);
    end if;
  end proc);

eval_for_Simplify_tbl := table(
  [ `Int`=`int`
  , `Sum`=`sum`
  , `Product`=`product`
  ]);

eval_for_Simplify := proc(e,kb,$)
  eval_in_ctx(
    proc(x,kb1)
      subsindets(x, {seq(specfunc(q),q=[indices(eval_for_Simplify_tbl, nolist)])},
                 y -> KB:-kb_eval_mb(eval_for_Simplify_tbl[op(0,y)],y,kb1));
    end proc, e, kb);
end proc;

eval_in_ctx_tbl := table(
  [ `PARTITION` = ((e,kb,ev)->KB:-kb_Partition(e,kb,a->a,ev))
  , `piecewise` = ((e,kb,ev)->KB:-kb_piecewise(e,kb,a->a,ev))
  ]);

eval_in_ctx := proc(ev, e, kb, $)
  if assigned(eval_in_ctx_tbl[op(0,e)]) then
    eval_in_ctx_tbl[op(0,e)](e,kb,curry(eval_in_ctx, ev));
  elif has(e, {indices(eval_in_ctx_tbl,nolist)}) then
    map(x->eval_in_ctx(ev,x,kb),e);
  else
    ev(e,kb);
  end if;
end proc;

# Testing

TestSimplify := proc(m, t, n::algebraic:=m, {verify:=simplify})
  local s, r;
  # How to pass keyword argument {ctx::list:=[]} on to Simplify?
  s, r := selectremove(type, [_rest], 'identical(ctx)=anything');
  CodeTools[Test](Simplify(m,t,op(s)), n, measure(verify), op(r))
end proc;

TestHakaru := proc(m, n::{set(algebraic),algebraic}:=m,
                   {simp:=improve, verify:=simplify, ctx::list:=[]})
  local kb := build_kb(ctx, "TestHakaru"), ver := measure(verify);
  ver := `if`(n::set, 'member'(ver), ver);

  CodeTools[Test](fromLO(simp(toLO(m), _ctx=kb), _ctx=kb), n,
    ver, _rest)
end proc;

TestDisint := module()
    export ModuleApply := proc(
      M::{t_Hakaru, list(anything)}, #args to disint, or just 1st arg
      n::set({t_Hakaru, identical(NULL)}), #desired return
      ctx::t_kb_atoms:= [], #context: assumptions, "knowledge"
      TLim::{positive, identical(-1)}:= 80 #timelimit
    )
      local disint_args, disint_var, expected := n;
      if M :: list then
        disint_args := [op(M),ctx];
      else
        disint_var := gensym('t');
        disint_args := [M,disint_var,ctx];
        expected := subs(:-`t`=disint_var,expected);
      end if;
      try
        do_test(disint_args, copy(expected), TLim, _rest);
      catch "time expired":
        error "Time expired while running: disint(%1)", disint_args;
      end try;
    end proc;

    # This is necessary because CodeTools seems to forgot the value
    # of our local variables (but only the `expected result' arg)
    # unless that arg is precisely a formal parameter, and we `copy' the
    # input to this function.
    local do_test := proc(disint_args, expected, tlim)
      timelimit( tlim, CodeTools[Test]
                 ( {disint(op(disint_args))}
                 , expected
                 , '`subset`(measure(simplify))'
                 , _rest));
    end proc;
end module;

TestEfficient := proc(e, t::t_type, t_kb := KB:-empty, {label::string := "Test" })
  local out, result;
  out := SimplifyKB(args[1..3]);

  _Env_TestTools_Try_printf := false;
  result := TestTools[Try](label, Efficient(out),true);
  if result = NULL then
    printf("%s passed.\n", label);
  else
    error sprintf("%s FAILED.\n"
                  "The result of\n\t%a\n\tis not efficient.\n"
                 , label, todo );
  end if;
end proc;

# Test roughly for "efficient" Hakaru measure terms,
# i.e., those we want simplification to produce.
Efficient := proc(mm, $)
  local m, n;
  m := mm;
  if has(m, 'undefined') then
    return false;
  end if;
  while m :: '{lam(name, anything, anything),
               Context(anything, anything),
               case(anything, Branches(Branch(anything, anything))),
               And(specfunc(piecewise)
                  ,{anyfunc(anything, anything, Msum())
                   ,anyfunc(anything, anything, anything, Msum())})}' do
    m := op(`if`(op(0,m)='lam',3,`if`(op(0,m)='case',[2,1,2],2)),m);
  end do;
  if m :: 'Weight(anything, anything)' then m := op(2,m) end if;
  if has(m, '{infinity, Lebesgue, int, Int, Beta, GAMMA}') then
    return false;
  end if;
  for n in `if`(m :: 'specfunc(Msum)', m, [m]) do
    if n :: 'Weight(anything, anything)' then n := op(2,n) end if;
    if has(subsindets(n, 'specfunc(Weight(anything, anything), Msum)',
                      s -> `if`(Testzero(`+`(op(map2(op, 1, s))) - 1),
                                map2(op, 2, s), s)),
           '{Msum, Weight}') then
      return false;
    end if;
  end do;
  return true;
end proc;

Profile := module()
  option package;
  export ModuleApply, GetProf, PPrProf, modules_to_profile, names_to_profile;
  local ModuleLoad, cl, profile_flag_to_ord, name_to_string, take;

  modules_to_profile := proc()
    kernelopts(opaquemodules=false):
    { 'BindingTools', 'Hakaru', 'KB', 'Partition', 'Loop'
    , 'Domain', 'NewSLO', 'Summary'
    , entries(Domain:-Improve:-Simplifiers, nolist)
    };
  end proc();

  cl := proc(f,x,$)
    local rs := f(x) minus x;
    if rs={} then x else cl(f,rs) end if;
  end proc;

  take := proc(xs,n,$)
    op(1,[ListTools[LengthSplit](xs,n)]);
  end proc;

  names_to_profile := proc()
    local ns;
    kernelopts(opaquemodules=false):
    ns := cl(curry(map,x->CodeTools:-Profiling:-getMemberFuncs(x,true)), modules_to_profile);
    map(proc(n)
          if n::`module`('ModuleApply') then 'n[ModuleApply]' elif n::procedure then n else NULL end if
        end proc, ns);
  end proc();

  name_to_string := (x->convert(x,'string'));

  profile_flag_to_ord := table(
     ['alpha' = (proc (a, b) lexorder(a[1],b[1]) end proc)
     ,'ralpha' = (proc (a, b) not lexorder(a[1],b[1]) end proc)
     ,'time' = (proc (a, b) evalb(a[4] < b[4]) end proc)
     ,'rtime' = (proc (a, b) evalb(b[4] < a[4]) end proc)
     ,'bytes' = (proc (a, b) evalb(a[6] < b[6]) end proc)
     ,'rbytes' = (proc (a, b) evalb(b[6] < a[6]) end proc)
     ,'load' = (proc (a, b) evalb(a[6]*a[6]*a[4] < b[6]*b[6]*b[4]) end proc)
     ,'rload' = (proc (a, b) evalb(b[6]*b[6]*b[4] < a[6]*a[6]*a[4]) end proc)
     ]);

  GetProf := proc(fns::({list,set})(satisfies(x->member(x,:-profile_profiled)))
                 ,{_flag:='rload'}
                 )
    local i, totaltime, totalbytes, totaldepth, totalcalls, timepc, bytespc, numargs, displist, totaltimepc, totalbytespc
         , ix, get_timepc, get_bytespc, get_nm, nm, flag ;
    global profile_time, profile_bytes, profile_maxdepth, profile_calls, profile_profiled;

    flag := _flag;
    totaltime, totalbytes, totalcalls, totaldepth := 0$4;
    numargs := nops(fns);

    for i to nops(profile_profiled) do
      ix := name_to_string(profile_profiled[i]);
      totaltime := totaltime+profile_time[ix];
      totalbytes := totalbytes+profile_bytes[ix];
      totalcalls := totalcalls+profile_calls[ix];
      totaldepth := totaldepth+profile_maxdepth[ix];
    end do;

    if totaltime = 0 then
      get_timepc := i->0;
      totaltimepc := 0;
    else
      get_timepc := i->100*profile_time[name_to_string(profile_profiled[i])]/totaltime;
      totaltimepc := 100;
    end if;
    for i to nops(profile_profiled) do
      timepc[name_to_string(profile_profiled[i])] := get_timepc(i);
    end do;

    if totalbytes = 0 then
      get_bytespc := i->0;
      totalbytespc := 0;
    else
      get_bytespc := i->100*profile_bytes[name_to_string(profile_profiled[i])]/totalbytes;
      totalbytespc := 100;
    end if;
    for i to nops(profile_profiled) do
      bytespc[name_to_string(profile_profiled[i])] := get_bytespc(i);
    end do;

    displist := [];
    if 0 < numargs then
      get_nm := i->op(i,fns);
    else
      numargs := nops(profile_profiled);
      get_nm := i->profile_profiled[i];
    end if;
    for i to numargs do
      nm := get_nm(i); ix := name_to_string(nm);
      displist := [op(displist),
                   [nm, map(q->q[ix],[profile_maxdepth, profile_calls,
                                      profile_time, timepc, profile_bytes, bytespc])[]  ]];
    end do;

    displist := sort(displist, profile_flag_to_ord[flag]);
    displist, [totaldepth,totalcalls,totaltime,totaltimepc,totalbytes,totalbytespc];
  end proc;

  PPrProf := proc(dat,tot,{_max_name_len:=55,_prof_name:=`function`})
    local i, k, pr_nm;
    k := _max_name_len; pr_nm := _prof_name;

    printf(cat(pr_nm,(" "$k-3),`depth    calls     time    time%%     `));
    printf(`    bytes   bytes%%\n`);
    printf(cat("--"$k+1,`\n`));
    for i from 1 to nops(dat)-1 do
      printf(cat(`%-`,convert(k,string),`a%7d%9d%9.3f%9.2f%14d%9.2f\n`),
             op(1..7,dat[i]));
    end do;
    printf(cat("--"$k+1,`\n`));
    printf(cat(`%-`,convert(k,string),`a%7d%9d%9.3f%9.2f%14d%9.2f\n\n`),
           `total:`,op(1..6,tot));
    return NULL
  end proc;

  ModuleApply := proc(f,{_args:=[]})
    local res, nppr, rm_ppr, prf, tot, as; as := _args;
    if assigned(_Env_Profile_count_ppr) then
      nppr := _Env_Profile_count_ppr;
    else nppr := 25; end if;
    if assigned(_Env_Profile_remove_ppr) then
      rm_ppr := _Env_Profile_remove_ppr;
    else rm_ppr := (x->andmap(q->op(q,x)<0.001,[3,4,6])); end if;

    unprofile(); profile(op(names_to_profile));
    if   f::string then res := NULL; read(f);
    else                res := f(op(as)); end if;
    prf, tot := GetProf(names_to_profile,_rest);
    unprofile();
    prf := remove(rm_ppr, prf);
    PPrProf(take(prf,nppr),tot,_rest);
    res;
  end proc;

  ModuleLoad := proc($)
    unprotect(:-convert);
    :-convert := overload([proc(x::name,_::identical(string),$) option overload(callseq_only); sprintf("%a",x) end proc
                          ,:-convert]);
    protect(:-convert);
    map(unprotect,[modules_to_profile, names_to_profile]);
    NULL;
  end proc;
  ModuleLoad();
end module;

# Load a file in concrete Hakaru syntax (using the "momiji" command)
# and return its term (in which Sum and Product are inert) and type.
Concrete := proc(path::string, $)
  local cmd, res, dangerous_chars;
  cmd := FileTools:-AbsolutePath(path,
    (FileTools:-ParentDirectory@@2)(LibraryTools:-FindLibrary(Hakaru)));
  dangerous_chars := [ " ", "'", """", `if`(kernelopts(platform)="windows", [], ["\\"])[] ];
  if ormap((c->StringTools:-Has(cmd,c)), dangerous_chars) then
    error "Dangerous characters in path: %1", cmd;
  end if;
  cmd := cat("momiji ", cmd);
  res := ssystem(cmd);
  if res :: [0, string] then
    parse(cat("use Hakaru in ", op(2,res), " end use"));
  else
    error "ssystem %1: %2", cmd, res;
  end if;
end proc;

# This module forms part of NewSLO and is `$include`d there

RoundTrip := proc(e, t::t_type)
  local result;
  interface(screenwidth=9999, prettyprint=0, warnlevel=0,
    showassumed=0,quiet=true);
  kernelopts(assertlevel=0);
  result := eval(ToInert(Simplify(_passed)), _Inert_ATTRIBUTE=NULL);
  lprint(result)
end proc;

Simplify := proc(e, t::t_type, {ctx :: list := []}, $)
  subsindets(SimplifyKB(e, t, build_kb(ctx, "Simplify")),
             And({t_sum, t_product}, anyfunc(anything, anything=range)),
             e -> subsop(0 = `if`(e::t_sum, SumIE, ProductIE),
                         applyop(`+`, [2,2,2], e, 1)))
end proc;

SimplifyKB_ := proc(leaf, e, t::t_type, kb::t_kb, $)
  local patterns, x, kb1, ex;
  if t :: HFunction(anything, anything) then
    patterns := htype_patterns(op(1,t));
    if patterns :: Branches(Branch(PVar(name),anything)) then
      # Eta-expand the function type
      x := `if`(e::lam(name,anything,anything), op(1,e),
                op([1,1,1],patterns));
      x, kb1 := genType(x, op(1,t), kb, e);
      ex := app(e,x);
      lam(x, op(1,t), SimplifyKB_(leaf,ex, op(2,t), kb1))
    else
      # Eta-expand the function type and the sum-of-product argument-type
      x := `if`(e::lam(name,anything,anything), op(1,e), d);
      if depends([e,t,kb], x) then x := gensym(x) end if;
      ex := app(e,x);
      lam(x, op(1,t), 'case'(x,
        map(proc(branch)
            local eSubst, pSubst, p1, binds, y, kb1, i, pSubst1;
              eSubst, pSubst := pattern_match([x,e], x, op(1,branch));
              p1 := subs(pSubst, op(1,branch));
              binds := [pattern_binds(p1)];
              kb1 := kb;
              pSubst1 := table();
              for i from 1 to nops(binds) do
                y, kb1 := genType(op(i,binds), op([2,i],branch), kb1);
                pSubst1[op(i,binds)] := y;
              end do;
              pSubst1 := op(op(pSubst1));
              Branch(subs(pSubst1, p1),
                     SimplifyKB_(leaf,eval(eval(ex,eSubst),pSubst1), op(2,t), kb1))
            end proc,
            patterns)))
    end if
  else
    leaf(e,t,kb)
  end if
end proc;

SimplifyKB := curry(SimplifyKB_,
  proc(e0,t,kb)
    local e := eval_for_Simplify(e0,kb);
    if t :: HMeasure(anything) then
      fromLO(improve(toLO(e), _ctx=kb), _ctx=kb);
    else
      simplify_assuming(e,kb);
    end if;
  end proc);

eval_for_Simplify_tbl := table(
  [ `Int`=`int`
  , `Sum`=`sum`
  , `Product`=`product`
  ]);

eval_for_Simplify := proc(e,kb,$)
  eval_in_ctx(
    proc(x,kb1)
      subsindets(x, {seq(specfunc(q),q=[indices(eval_for_Simplify_tbl, nolist)])},
                 y -> KB:-kb_eval_mb(eval_for_Simplify_tbl[op(0,y)],y,kb1));
    end proc, e, kb);
end proc;

eval_in_ctx_tbl := table(
  [ `PARTITION` = ((e,kb,ev)->KB:-kb_Partition(e,kb,a->a,ev))
  , `piecewise` = ((e,kb,ev)->KB:-kb_piecewise(e,kb,a->a,ev))
  ]);

eval_in_ctx := proc(ev, e, kb, $)
  if assigned(eval_in_ctx_tbl[op(0,e)]) then
    eval_in_ctx_tbl[op(0,e)](e,kb,curry(eval_in_ctx, ev));
  elif has(e, {indices(eval_in_ctx_tbl,nolist)}) then
    map(x->eval_in_ctx(ev,x,kb),e);
  else
    ev(e,kb);
  end if;
end proc;

# Testing

TestSimplify := proc(m, t, n::algebraic:=m, {verify:=simplify})
  local s, r;
  # How to pass keyword argument {ctx::list:=[]} on to Simplify?
  s, r := selectremove(type, [_rest], 'identical(ctx)=anything');
  CodeTools[Test](Simplify(m,t,op(s)), n, measure(verify), op(r))
end proc;

TestHakaru := proc(m, n::{set(algebraic),algebraic}:=m,
                   {simp:=improve, verify:=simplify, ctx::list:=[]})
  local kb := build_kb(ctx, "TestHakaru"), ver := measure(verify);
  ver := `if`(n::set, 'member'(ver), ver);

  CodeTools[Test](fromLO(simp(toLO(m), _ctx=kb), _ctx=kb), n,
    ver, _rest)
end proc;

TestDisint := module()
    export ModuleApply := proc(
      M::{t_Hakaru, list(anything)}, #args to disint, or just 1st arg
      n::set({t_Hakaru, identical(NULL)}), #desired return
      ctx::t_kb_atoms:= [], #context: assumptions, "knowledge"
      TLim::{positive, identical(-1)}:= 80 #timelimit
    )
      local disint_args, disint_var, expected := n;
      if M :: list then
        disint_args := [op(M),ctx];
      else
        disint_var := gensym('t');
        disint_args := [M,disint_var,ctx];
        expected := subs(:-`t`=disint_var,expected);
      end if;
      try
        do_test(disint_args, copy(expected), TLim, _rest);
      catch "time expired":
        error "Time expired while running: disint(%1)", disint_args;
      end try;
    end proc;

    # This is necessary because CodeTools seems to forgot the value
    # of our local variables (but only the `expected result' arg)
    # unless that arg is precisely a formal parameter, and we `copy' the
    # input to this function.
    local do_test := proc(disint_args, expected, tlim)
      timelimit( tlim, CodeTools[Test]
                 ( {disint(op(disint_args))}
                 , expected
                 , '`subset`(measure(simplify))'
                 , _rest));
    end proc;
end module;

TestEfficient := proc(e, t::t_type, t_kb := KB:-empty, {label::string := "Test" })
  local out, result;
  out := SimplifyKB(args[1..3]);

  _Env_TestTools_Try_printf := false;
  result := TestTools[Try](label, Efficient(out),true);
  if result = NULL then
    printf("%s passed.\n", label);
  else
    error sprintf("%s FAILED.\n"
                  "The result of\n\t%a\n\tis not efficient.\n"
                 , label, todo );
  end if;
end proc;

# Test roughly for "efficient" Hakaru measure terms,
# i.e., those we want simplification to produce.
Efficient := proc(mm, $)
  local m, n;
  m := mm;
  if has(m, 'undefined') then
    return false;
  end if;
  while m :: '{lam(name, anything, anything),
               Context(anything, anything),
               case(anything, Branches(Branch(anything, anything))),
               And(specfunc(piecewise)
                  ,{anyfunc(anything, anything, Msum())
                   ,anyfunc(anything, anything, anything, Msum())})}' do
    m := op(`if`(op(0,m)='lam',3,`if`(op(0,m)='case',[2,1,2],2)),m);
  end do;
  if m :: 'Weight(anything, anything)' then m := op(2,m) end if;
  if has(m, '{infinity, Lebesgue, int, Int, Beta, GAMMA}') then
    return false;
  end if;
  for n in `if`(m :: 'specfunc(Msum)', m, [m]) do
    if n :: 'Weight(anything, anything)' then n := op(2,n) end if;
    if has(subsindets(n, 'specfunc(Weight(anything, anything), Msum)',
                      s -> `if`(Testzero(`+`(op(map2(op, 1, s))) - 1),
                                map2(op, 2, s), s)),
           '{Msum, Weight}') then
      return false;
    end if;
  end do;
  return true;
end proc;

Profile := module()
  option package;
  export ModuleApply, GetProf, PPrProf, modules_to_profile, names_to_profile;
  local ModuleLoad, cl, profile_flag_to_ord, name_to_string, take;

  modules_to_profile := proc()
    kernelopts(opaquemodules=false):
    { 'BindingTools', 'Hakaru', 'KB', 'Partition', 'Loop'
    , 'Domain', 'NewSLO', 'Summary'
    , entries(Domain:-Improve:-Simplifiers, nolist)
    };
  end proc();

  cl := proc(f,x,$)
    local rs := f(x) minus x;
    if rs={} then x else cl(f,rs) end if;
  end proc;

  take := proc(xs,n,$)
    op(1,[ListTools[LengthSplit](xs,n)]);
  end proc;

  names_to_profile := proc()
    local ns;
    kernelopts(opaquemodules=false):
    ns := cl(curry(map,x->CodeTools:-Profiling:-getMemberFuncs(x,true)), modules_to_profile);
    map(proc(n)
          if n::`module`('ModuleApply') then 'n[ModuleApply]' elif n::procedure then n else NULL end if
        end proc, ns);
  end proc();

  name_to_string := (x->convert(x,'string'));

  profile_flag_to_ord := table(
     ['alpha' = (proc (a, b) lexorder(a[1],b[1]) end proc)
     ,'ralpha' = (proc (a, b) not lexorder(a[1],b[1]) end proc)
     ,'time' = (proc (a, b) evalb(a[4] < b[4]) end proc)
     ,'rtime' = (proc (a, b) evalb(b[4] < a[4]) end proc)
     ,'bytes' = (proc (a, b) evalb(a[6] < b[6]) end proc)
     ,'rbytes' = (proc (a, b) evalb(b[6] < a[6]) end proc)
     ,'load' = (proc (a, b) evalb(a[6]*a[6]*a[4] < b[6]*b[6]*b[4]) end proc)
     ,'rload' = (proc (a, b) evalb(b[6]*b[6]*b[4] < a[6]*a[6]*a[4]) end proc)
     ]);

  GetProf := proc(fns::({list,set})(satisfies(x->member(x,:-profile_profiled)))
                 ,{_flag:='rload'}
                 )
    local i, totaltime, totalbytes, totaldepth, totalcalls, timepc, bytespc, numargs, displist, totaltimepc, totalbytespc
         , ix, get_timepc, get_bytespc, get_nm, nm, flag ;
    global profile_time, profile_bytes, profile_maxdepth, profile_calls, profile_profiled;

    flag := _flag;
    totaltime, totalbytes, totalcalls, totaldepth := 0$4;
    numargs := nops(fns);

    for i to nops(profile_profiled) do
      ix := name_to_string(profile_profiled[i]);
      totaltime := totaltime+profile_time[ix];
      totalbytes := totalbytes+profile_bytes[ix];
      totalcalls := totalcalls+profile_calls[ix];
      totaldepth := totaldepth+profile_maxdepth[ix];
    end do;

    if totaltime = 0 then
      get_timepc := i->0;
      totaltimepc := 0;
    else
      get_timepc := i->100*profile_time[name_to_string(profile_profiled[i])]/totaltime;
      totaltimepc := 100;
    end if;
    for i to nops(profile_profiled) do
      timepc[name_to_string(profile_profiled[i])] := get_timepc(i);
    end do;

    if totalbytes = 0 then
      get_bytespc := i->0;
      totalbytespc := 0;
    else
      get_bytespc := i->100*profile_bytes[name_to_string(profile_profiled[i])]/totalbytes;
      totalbytespc := 100;
    end if;
    for i to nops(profile_profiled) do
      bytespc[name_to_string(profile_profiled[i])] := get_bytespc(i);
    end do;

    displist := [];
    if 0 < numargs then
      get_nm := i->op(i,fns);
    else
      numargs := nops(profile_profiled);
      get_nm := i->profile_profiled[i];
    end if;
    for i to numargs do
      nm := get_nm(i); ix := name_to_string(nm);
      displist := [op(displist),
                   [nm, map(q->q[ix],[profile_maxdepth, profile_calls,
                                      profile_time, timepc, profile_bytes, bytespc])[]  ]];
    end do;

    displist := sort(displist, profile_flag_to_ord[flag]);
    displist, [totaldepth,totalcalls,totaltime,totaltimepc,totalbytes,totalbytespc];
  end proc;

  PPrProf := proc(dat,tot,{_max_name_len:=55,_prof_name:=`function`})
    local i, k, pr_nm;
    k := _max_name_len; pr_nm := _prof_name;

    printf(cat(pr_nm,(" "$k-3),`depth    calls     time    time%%     `));
    printf(`    bytes   bytes%%\n`);
    printf(cat("--"$k+1,`\n`));
    for i from 1 to nops(dat)-1 do
      printf(cat(`%-`,convert(k,string),`a%7d%9d%9.3f%9.2f%14d%9.2f\n`),
             op(1..7,dat[i]));
    end do;
    printf(cat("--"$k+1,`\n`));
    printf(cat(`%-`,convert(k,string),`a%7d%9d%9.3f%9.2f%14d%9.2f\n\n`),
           `total:`,op(1..6,tot));
    return NULL
  end proc;

  ModuleApply := proc(f,{_args:=[]})
    local res, nppr, rm_ppr, prf, tot, as; as := _args;
    if assigned(_Env_Profile_count_ppr) then
      nppr := _Env_Profile_count_ppr;
    else nppr := 25; end if;
    if assigned(_Env_Profile_remove_ppr) then
      rm_ppr := _Env_Profile_remove_ppr;
    else rm_ppr := (x->andmap(q->op(q,x)<0.001,[3,4,6])); end if;

    unprofile(); profile(op(names_to_profile));
    if   f::string then res := NULL; read(f);
    else                res := f(op(as)); end if;
    prf, tot := GetProf(names_to_profile,_rest);
    unprofile();
    prf := remove(rm_ppr, prf);
    PPrProf(take(prf,nppr),tot,_rest);
    res;
  end proc;

  ModuleLoad := proc($)
    unprotect(:-convert);
    :-convert := overload([proc(x::name,_::identical(string),$) option overload(callseq_only); sprintf("%a",x) end proc
                          ,:-convert]);
    protect(:-convert);
    map(unprotect,[modules_to_profile, names_to_profile]);
    NULL;
  end proc;
  ModuleLoad();
end module;

# Load a file in concrete Hakaru syntax (using the "momiji" command)
# and return its term (in which Sum and Product are inert) and type.
Concrete := proc(path::string, $)
  local cmd, res, dangerous_chars;
  cmd := FileTools:-AbsolutePath(path,
    (FileTools:-ParentDirectory@@2)(LibraryTools:-FindLibrary(Hakaru)));
  dangerous_chars := [ " ", "'", """", `if`(kernelopts(platform)="windows", [], ["\\"])[] ];
  if ormap((c->StringTools:-Has(cmd,c)), dangerous_chars) then
    error "Dangerous characters in path: %1", cmd;
  end if;
  cmd := cat("momiji ", cmd);
  res := ssystem(cmd);
  if res :: [0, string] then
    parse(cat("use Hakaru in ", op(2,res), " end use"));
  else
    error "ssystem %1: %2", cmd, res;
  end if;
end proc;


at least generate AST for piecewise

at least generate AST for piecewise

# SLO = Simplify Linear Operator.
#
#  This assumes that the input is the output of Language.Hakaru.Syntax.tester
# No checking is done that this is actually the case.
#
# SLO : simplifier
# AST : takes simplified form and transform to AST
#

SLO := module ()
  export ModuleApply, AST, simp, c; # very important: this c is "global".
  local ToAST, t_binds, t_pw, into_pw, myprod, gensym, gs_counter, do_pw;

  t_binds := 'specfunc(anything, {int, Int, sum, Sum})';
  t_pw := 'specfunc(anything, piecewise)';

  ModuleApply := proc(inp::anything)
    local e;
    try
      simp(inp(c));
    catch "Wrong kind of parameters in piecewise":
      error "Bug in Hakaru -> Maple translation, piecewise used incorrectly.";
    end try;
  end proc;

  # AST transforms the Maple to a representation of the mochastic AST
  AST := proc(inp::anything)
    local cs;
    cs := indets(inp, 'specfunc'(anything,c));
    # deal with trivial input first
    if inp=0 then
        0
    # then deal with 'bad' input
    elif nops(cs) = 0 then
      error "the constant", inp, " is not a measure."
    elif type(inp, `+`) then
      map(AST, SUM(op(inp)))
    else
      ToAST(inp, []);
    end if;
  end proc;

  # recursive function which does the main translation
  ToAST := proc(e, ctx)
    local a0, a1, var, vars, rng, ee, cof, d, ld, weight, binders,
      v, subst, ivars, ff, newvar, rest;
    if type(e, specfunc(name, c)) then
        return Return(op(e))
    # we might have recursively encountered a hidden 0
    elif (e = 0) then
       return 0
    # we might have done something odd, and there is no x anymore (and not 0)
    elif type(e, 'numeric') then
      error "the constant", e, "is not a measure"
    # invariant: we depend on c
    else
      binders := indets(e, t_binds);
      vars := indets(e, specfunc(anything, c));
      subst := map(x-> x = op(0,x)[op(x)], vars);
      ivars := map2(op, 2, subst);
      if binders = {} then
        # this is a 'raw' measure, with no integrals
        ee := subs(subst, e);
        if type(ee, 'polynom'(anything,ivars)) then
          ee := collect(ee, ivars);
          d := degree(ee, ivars);
          ld := ldegree(ee, ivars);
          cof := [coeffs(ee, ivars, 'v')]; # cof and v are lists
          if (d = 1) and (ld = 1) then
            # WM = Weight-Measure pair
            ff := (x,y) -> WM(simplify(x), Return(op(y)));
            Superpose(op(zip(ff, cof, v)));
            # `if`(cof=1, rest, Bind_(Factor(simplify(cof)), rest))
          else
            if (ld = 0) then
              error "non-zero constant encountered as a measure", ee
            else
              error "polynomial in c:", ee
            end if;
          end if;
        elif type(ee, t_pw) then
          # for now, don't simplify, just pass through
          return do_pw([op(e)], ctx);
        else
          error "no binders, but still not a polynomial?", ee
        end if;
      else
        if type(e, 'specfunc'(anything, {'int','Int'})) then
          var, rng := op(op(2,e));
          ee := op(1,e);
          weight := simplify(op(2,rng)-op(1,rng));
          if type(weight, 'SymbolicInfinity') then
            rest := ToAST(ee, [op(2,e), op(ctx)]);
            # should recognize densities here
            Bind(Lebesgue, var = rng, rest)
          else
            rest := ToAST(weight*ee, [op(2,e), op(ctx)]);
            # process the rest, and then recognize
            # recognize 'raw' uniform
            if type(rest, specfunc(identical(var), 'Return')) then
              Uniform(op(rng));
            elif type(rest, 'Superpose'('WM'(anything, anything))) then
              # finite range.
              weight := simplify(op([1,1], rest));
              ee := op([1,2], rest);
              if ctx=[] and type(ee, Return(anything)) then
                Bind(Uniform(op(1, rng), op(2, rng)), var,
                    Superpose(WM(weight, simplify(ee))))
              else
                error "almost uniform but not quite?", e
              end if;
            else
              Bind(Lebesgue, var = rng, rest)
            end if;
          end if;
        elif type(e, 'specfunc'(anything, {'sum','Sum'})) then
            error "sums not handled yet"
        else
            error "constants should have been pushed inside already", e
        end if;
      end if;
    end if;
  end proc;

  # simp mostly pushes things in.
  simp := proc(e)
    local a, b, d;
    if type(e, `+`) then
      map(simp, e)
    elif type(e, `*`) then
      a, b := selectremove(type, e, t_binds);
      # now casesplit on what a is
      if a=1 then  # no binders
        a, b := selectremove(type, e, t_pw);
        if a=1 then # and no piecewise either
          d := expand(b); # probably need to write something less brutal
          if b=d then # nothing happened
            simplify(b)
          else # this might be better
            simp(d)
          end if
        elif type(a, `*`) then
          error "do not know how to multiply 2 pw:", a
        elif type(a, t_pw) then
          into_pw(b, a)
        else
          error "something weird happened:", a, " was supposed to be pw"
        end if
      elif type(a, `*`) then
        error "product of 2 binders?!?", a
      else
        subsop(1=myprod(simp(b),simp(op(1,a))), a)
      end if
    elif type(e, t_binds) then
      subsop(1=simp(op(1,e)), e)
    # need to go into pw even if there is no factor to push in
    elif type(e, t_pw) then
      into_pw(1, e)
    else
      simplify(e)
    end if;
  end;

  into_pw := proc(fact, pw)
    local n, f;

    n := nops(pw);
    f := proc(j)
      if j=n then # last one is special, always a value
        simp(myprod(fact, simp(op(j, pw))))
      elif type(j,'odd') then # a condition
        op(j, pw)
      else # j even
        simp(myprod(fact , simp(op(j, pw))))
      end if;
    end proc;
    piecewise(seq(f(i),i=1..n))
  end proc;

  # myprod takes care of pushing a product inside a `+`
  myprod := proc(a, b)
    if type(b,`+`) then
      map2(myprod, a, b)
    else
      a*b
    end if;
  end proc;

  gs_counter := 0;
  gensym := proc(x::name) gs_counter := gs_counter + 1; x || gs_counter; end proc;

  do_pw := proc(l, ctx)
    local len;
    len := nops(l);
    if len = 0 then 0
    elif len = 1 then ToAST(l[1], ctx)
    else # l>=2. Note how conditions go through straight
      If(l[1], ToAST(l[2], ctx), do_pw(l[3..-1], ctx))
    end if;
  end;
end;

# this has to be global!
unsafeProb := proc(v)
  if signum(0, v, 1) = 1 then v else 'unsafeProb'(v) end if;
end proc;

# will get called with 'unsafeProb(...)'
`simplify/unsafeProb` := proc(a) local b;
  b := op(1,a);
  if type(b, 'exp'(anything)) then exp_(op(1, b)) else a end if;
end proc;

# SLO = Simplify Linear Operator.
#
#  This assumes that the input is the output of Language.Hakaru.Syntax.tester
# No checking is done that this is actually the case.
#
# SLO : simplifier
# AST : takes simplified form and transform to AST
#

SLO := module ()
  export ModuleApply, AST, simp, c; # very important: this c is "global".
  local ToAST, t_binds, t_pw, into_pw, myprod, gensym, gs_counter;

  t_binds := 'specfunc(anything, {int, Int, sum, Sum})';
  t_pw := 'specfunc(anything, piecewise)';

  ModuleApply := proc(inp::anything)
    local e;
    try
      simp(inp(c));
    catch "Wrong kind of parameters in piecewise":
      error "Bug in Hakaru -> Maple translation, piecewise used incorrectly.";
    end try;
  end proc;

  # AST transforms the Maple to a representation of the mochastic AST
  AST := proc(inp::anything)
    local cs;
    cs := indets(inp, 'specfunc'(anything,c));
    # deal with trivial input first
    if inp=0 then
        0
    # then deal with 'bad' input
    elif nops(cs) = 0 then
      error "the constant", inp, " is not a measure."
    elif type(inp, `+`) then
      map(AST, SUM(op(inp)))
    else
      ToAST(inp, []);
    end if;
  end proc;

  # recursive function which does the main translation
  ToAST := proc(e, ctx)
    local a0, a1, var, vars, rng, ee, cof, d, ld, weight, binders,
      v, subst, ivars, ff, newvar, rest;
    if type(e, specfunc(name, c)) then
        return Return(op(e))
    # we might have recursively encountered a hidden 0
    elif (e = 0) then
       return 0
    # we might have done something odd, and there is no x anymore (and not 0)
    elif type(e, 'numeric') then
      error "the constant", e, "is not a measure"
    # invariant: we depend on c
    else
      binders := indets(e, t_binds);
      vars := indets(e, specfunc(anything, c));
      subst := map(x-> x = op(0,x)[op(x)], vars);
      ivars := map2(op, 2, subst);
      if binders = {} then
        # this is a 'raw' measure, with no integrals
        ee := subs(subst, e);
        if type(ee, 'polynom'(anything,ivars)) then
          ee := collect(ee, ivars);
          d := degree(ee, ivars);
          ld := ldegree(ee, ivars);
          cof := [coeffs(ee, ivars, 'v')]; # cof and v are lists
          if (d = 1) and (ld = 1) then
            # WM = Weight-Measure pair
            ff := (x,y) -> WM(simplify(x), Return(op(y)));
            Superpose(op(zip(ff, cof, v)));
            # `if`(cof=1, rest, Bind_(Factor(simplify(cof)), rest))
          else
            if (ld = 0) then
              error "non-zero constant encountered as a measure", ee
            else
              error "polynomial in c:", ee
            end if;
          end if;
        elif type(ee, t_pw) then
          error "encountered piecewise, case not done yet"
        else
          error "no binders, but still not a polynomial?", ee
        end if;
      else
        if type(e, 'specfunc'(anything, {'int','Int'})) then
          var, rng := op(op(2,e));
          ee := op(1,e);
          weight := simplify(op(2,rng)-op(1,rng));
          if type(weight, 'SymbolicInfinity') then
            rest := ToAST(ee, [op(2,e), op(ctx)]);
            # should recognize densities here
            Bind(Lebesgue, var = rng, rest)
          else
            rest := ToAST(weight*ee, [op(2,e), op(ctx)]);
            # process the rest, and then recognize
            # recognize 'raw' uniform
            if type(rest, specfunc(identical(var), 'Return')) then
              Uniform(op(rng));
            elif type(rest, 'Superpose'('WM'(anything, anything))) then
              # finite range.
              weight := simplify(op([1,1], rest));
              ee := op([1,2], rest);
              if ctx=[] and type(ee, Return(anything)) then
                Bind(Uniform(op(1, rng), op(2, rng)), var,
                    Superpose(WM(weight, simplify(ee))))
              else
                error "almost uniform but not quite?", e
              end if;
            else
              Bind(Lebesgue, var = rng, rest)
            end if;
          end if;
        elif type(e, 'specfunc'(anything, {'sum','Sum'})) then
            error "sums not handled yet"
        else
            error "constants should have been pushed inside already", e
        end if;
      end if;
    end if;
  end proc;

  # simp mostly pushes things in.
  simp := proc(e)
    local a, b, d;
    if type(e, `+`) then
      map(simp, e)
    elif type(e, `*`) then
      a, b := selectremove(type, e, t_binds);
      # now casesplit on what a is
      if a=1 then  # no binders
        a, b := selectremove(type, e, t_pw);
        if a=1 then # and no piecewise either
          d := expand(b); # probably need to write something less brutal
          if b=d then # nothing happened
            simplify(b)
          else # this might be better
            simp(d)
          end if
        elif type(a, `*`) then
          error "do not know how to multiply 2 pw:", a
        elif type(a, t_pw) then
          into_pw(b, a)
        else
          error "something weird happened:", a, " was supposed to be pw"
        end if
      elif type(a, `*`) then
        error "product of 2 binders?!?", a
      else
        subsop(1=myprod(simp(b),simp(op(1,a))), a)
      end if
    elif type(e, t_binds) then
      subsop(1=simp(op(1,e)), e)
    # need to go into pw even if there is no factor to push in
    elif type(e, t_pw) then
      into_pw(1, e)
    else
      simplify(e)
    end if;
  end;

  into_pw := proc(fact, pw)
    local n, f;

    n := nops(pw);
    f := proc(j)
      if j=n then # last one is special, always a value
        simp(myprod(fact, simp(op(j, pw))))
      elif type(j,'odd') then # a condition
        op(j, pw)
      else # j even
        simp(myprod(fact , simp(op(j, pw))))
      end if;
    end proc;
    piecewise(seq(f(i),i=1..n))
  end proc;

  # myprod takes care of pushing a product inside a `+`
  myprod := proc(a, b)
    if type(b,`+`) then
      map2(myprod, a, b)
    else
      a*b
    end if;
  end proc;

  gs_counter := 0;
  gensym := proc(x::name) gs_counter := gs_counter + 1; x || gs_counter; end proc;

end;

# this has to be global!
unsafeProb := proc(v)
  if signum(0, v, 1) = 1 then v else 'unsafeProb'(v) end if;
end proc;

# will get called with 'unsafeProb(...)'
`simplify/unsafeProb` := proc(a) local b;
  b := op(1,a);
  if type(b, 'exp'(anything)) then exp_(op(1, b)) else a end if;
end proc;