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lang: Add function values and lambdas

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This adds a giant missing piece of the language: proper function values!
It is lovely to now understand why early programming language designers
didn't implement these, but a joy to now reap the benefits of them. In
adding these, many other changes had to be made to get them to "fit"
correctly. This improved the code and fixed a number of bugs.
Unfortunately this touched many areas of the code, and since I was
learning how to do all of this for the first time, I've squashed most of
my work into a single commit. Some more information:

* This adds over 70 new tests to verify the new functionality.

* Functions, global variables, and classes can all be implemented
natively in mcl and built into core packages.

* A new compiler step called "Ordering" was added. It is called by the
SetScope step, and determines statement ordering and shadowing
precedence formally. It helped remove at least one bug and provided the
additional analysis required to properly capture variables when
implementing function generators and closures.

* The type unification code was improved to handle the new cases.

* Light copying of Node's allowed our function graphs to be more optimal
and share common vertices and edges. For example, if two different
closures capture a variable $x, they'll both use the same copy when
running the function, since the compiler can prove if they're identical.

* Some areas still need improvements, but this is ready for mainstream
testing and use!
This commit is contained in:
James Shubin
2019-06-04 21:51:21 -04:00
parent 4f1c463bdd
commit f53376cea1
189 changed files with 7170 additions and 849 deletions
Download Patch File Download Diff File Expand all files Collapse all files

277
lang/unification/simplesolver.go
View File

@@ -28,6 +28,23 @@ import (
const (
// Name is the prefix for our solver log messages.
Name = "solver: simple"
// ErrAmbiguous means we couldn't find a solution, but we weren't
// inconsistent.
ErrAmbiguous = interfaces.Error("can't unify, no equalities were consumed, we're ambiguous")
// AllowRecursion specifies whether we're allowed to use the recursive
// solver or not. It uses an absurd amount of memory, and might hang
// your system if a simple solution doesn't exist.
AllowRecursion = false
// RecursionDepthLimit specifies the max depth that is allowed.
// FIXME: RecursionDepthLimit is not currently implemented
RecursionDepthLimit = 5 // TODO: pick a better value ?
// RecursionInvariantLimit specifies the max number of invariants we can
// recurse into.
RecursionInvariantLimit = 5 // TODO: pick a better value ?
)
// SimpleInvariantSolverLogger is a wrapper which returns a
@@ -44,74 +61,90 @@ func SimpleInvariantSolverLogger(logf func(format string, v ...interface{})) fun
// It is intended to be very simple, even if it's computationally inefficient.
func SimpleInvariantSolver(invariants []interfaces.Invariant, expected []interfaces.Expr, logf func(format string, v ...interface{})) (*InvariantSolution, error) {
debug := false // XXX: add to interface
process := func(invariants []interfaces.Invariant) ([]interfaces.Invariant, []*ExclusiveInvariant, error) {
equalities := []interfaces.Invariant{}
exclusives := []*ExclusiveInvariant{}
for _, x := range invariants {
switch invariant := x.(type) {
case *EqualsInvariant:
equalities = append(equalities, invariant)
case *EqualityInvariant:
equalities = append(equalities, invariant)
case *EqualityInvariantList:
// de-construct this list variant into a series
// of equality variants so that our solver can
// be implemented more simply...
if len(invariant.Exprs) < 2 {
return nil, nil, fmt.Errorf("list invariant needs at least two elements")
}
for i := 0; i < len(invariant.Exprs)-1; i++ {
invar := &EqualityInvariant{
Expr1: invariant.Exprs[i],
Expr2: invariant.Exprs[i+1],
}
equalities = append(equalities, invar)
}
case *EqualityWrapListInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapMapInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapStructInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapFuncInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapCallInvariant:
equalities = append(equalities, invariant)
// contains a list of invariants which this represents
case *ConjunctionInvariant:
for _, invar := range invariant.Invariants {
equalities = append(equalities, invar)
}
case *ExclusiveInvariant:
// these are special, note the different list
if len(invariant.Invariants) > 0 {
exclusives = append(exclusives, invariant)
}
case *AnyInvariant:
equalities = append(equalities, invariant)
default:
return nil, nil, fmt.Errorf("unknown invariant type: %T", x)
}
}
return equalities, exclusives, nil
}
logf("%s: invariants:", Name)
for i, x := range invariants {
logf("invariant(%d): %T: %s", i, x, x)
}
solved := make(map[interfaces.Expr]*types.Type)
equalities := []interfaces.Invariant{}
exclusives := []*ExclusiveInvariant{}
// iterate through all invariants, flattening and sorting the list...
for _, x := range invariants {
switch invariant := x.(type) {
case *EqualsInvariant:
equalities = append(equalities, invariant)
case *EqualityInvariant:
equalities = append(equalities, invariant)
case *EqualityInvariantList:
// de-construct this list variant into a series
// of equality variants so that our solver can
// be implemented more simply...
if len(invariant.Exprs) < 2 {
return nil, fmt.Errorf("list invariant needs at least two elements")
}
for i := 0; i < len(invariant.Exprs)-1; i++ {
invar := &EqualityInvariant{
Expr1: invariant.Exprs[i],
Expr2: invariant.Exprs[i+1],
}
equalities = append(equalities, invar)
}
case *EqualityWrapListInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapMapInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapStructInvariant:
equalities = append(equalities, invariant)
case *EqualityWrapFuncInvariant:
equalities = append(equalities, invariant)
// contains a list of invariants which this represents
case *ConjunctionInvariant:
for _, invar := range invariant.Invariants {
equalities = append(equalities, invar)
}
case *ExclusiveInvariant:
// these are special, note the different list
if len(invariant.Invariants) > 0 {
exclusives = append(exclusives, invariant)
}
case *AnyInvariant:
equalities = append(equalities, invariant)
default:
return nil, fmt.Errorf("unknown invariant type: %T", x)
}
equalities, exclusives, err := process(invariants)
if err != nil {
return nil, err
}
// XXX: if these partials all shared the same variable definition, would
// it all work??? Maybe we don't even need the first map prefix...
listPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
mapPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
structPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
funcPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
callPartials := make(map[interfaces.Expr]map[interfaces.Expr]*types.Type)
isSolved := func(solved map[interfaces.Expr]*types.Type) bool {
for _, x := range expected {
@@ -461,6 +494,42 @@ Loop:
continue
}
case *EqualityWrapCallInvariant:
// the logic is slightly different here, because
// we can only go from the func type to the call
// type as we can't do the reverse determination
if _, exists := callPartials[eq.Expr2Func]; !exists {
callPartials[eq.Expr2Func] = make(map[interfaces.Expr]*types.Type)
}
if typ, exists := solved[eq.Expr2Func]; exists {
// wow, now known, so tell the partials!
if typ.Kind != types.KindFunc {
return nil, fmt.Errorf("expected: %s, got: %s", types.KindFunc, typ.Kind)
}
callPartials[eq.Expr2Func][eq.Expr1] = typ.Out
}
typ, ready := callPartials[eq.Expr2Func][eq.Expr1]
if ready { // ready to solve
if t, exists := solved[eq.Expr1]; exists {
if err := t.Cmp(typ); err != nil {
return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with call")
}
}
// sub checks
if t, exists := solved[eq.Expr2Func]; exists {
if err := t.Out.Cmp(typ); err != nil {
return nil, errwrap.Wrapf(err, "can't unify, invariant illogicality with call out")
}
}
solved[eq.Expr1] = typ // yay, we learned something!
used = append(used, i) // mark equality as used up
logf("%s: solved call wrap partial", Name)
continue
}
// regular matching
case *EqualityInvariant:
typ1, exists1 := solved[eq.Expr1]
@@ -533,16 +602,21 @@ Loop:
logf("%s: solved early with %d exclusives left!", Name, len(exclusives))
} else {
logf("%s: unsolved with %d exclusives left!", Name, len(exclusives))
if debug {
for i, x := range exclusives {
logf("%s: exclusive(%d) left: %s", Name, i, x)
}
}
}
// check for consistency against remaining invariants
logf("%s: checking for consistency against %d exclusives...", Name, len(exclusives))
done := []int{}
for i, invar := range exclusives {
// test each one to see if at least one works
match, err := invar.Matches(solved)
if err != nil {
if debug {
logf("exclusive invar failed: %+v", invar)
}
logf("exclusive invar failed: %+v", invar)
return nil, errwrap.Wrapf(err, "inconsistent exclusive")
}
if !match {
@@ -550,30 +624,19 @@ Loop:
}
done = append(done, i)
}
logf("%s: removed %d consistent exclusives...", Name, len(done))
// remove exclusives that matched correctly
// Remove exclusives that matched correctly.
for i := len(done) - 1; i >= 0; i-- {
ix := done[i] // delete index that was marked as done!
exclusives = append(exclusives[:ix], exclusives[ix+1:]...)
}
if len(exclusives) == 0 {
break Loop
// If we removed any exclusives, then we can start over.
if len(done) > 0 {
continue Loop
}
// TODO: Lastly, we could loop through each exclusive
// and see if it only has a single, easy solution. For
// example, if we know that an exclusive is A or B or C
// and that B and C are inconsistent, then we can
// replace the exclusive with a single invariant and
// then run that through our solver. We can do this
// iteratively (recursively in our case) so that if
// we're lucky, we rarely need to run the raw exclusive
// combinatorial solver which is slow.
// TODO: We could try and replace our combinatorial
// exclusive solver with a real SAT solver algorithm.
// what have we learned for sure so far?
partialSolutions := []interfaces.Invariant{}
logf("%s: %d solved, %d unsolved, and %d exclusives left", Name, len(solved), len(equalities), len(exclusives))
@@ -595,6 +658,69 @@ Loop:
}
}
// Lastly, we could loop through each exclusive and see
// if it only has a single, easy solution. For example,
// if we know that an exclusive is A or B or C, and that
// B and C are inconsistent, then we can replace the
// exclusive with a single invariant and then run that
// through our solver. We can do this iteratively
// (recursively for accuracy, but in our case via the
// simplify method) so that if we're lucky, we rarely
// need to run the raw exclusive combinatorial solver,
// which is slow.
logf("%s: attempting to simplify %d exclusives...", Name, len(exclusives))
done = []int{} // clear for re-use
simplified := []interfaces.Invariant{}
for i, invar := range exclusives {
// The partialSolutions don't contain any other
// exclusives... We look at each individually.
s, err := invar.simplify(partialSolutions) // XXX: pass in the solver?
if err != nil {
logf("exclusive simplification failed: %+v", invar)
continue
}
done = append(done, i)
simplified = append(simplified, s...)
}
logf("%s: simplified %d exclusives...", Name, len(done))
// Remove exclusives that matched correctly.
for i := len(done) - 1; i >= 0; i-- {
ix := done[i] // delete index that was marked as done!
exclusives = append(exclusives[:ix], exclusives[ix+1:]...)
}
// Add new equalities and exclusives onto state globals.
eq, ex, err := process(simplified) // process like at the top
if err != nil {
// programming error?
return nil, errwrap.Wrapf(err, "processing error")
}
equalities = append(equalities, eq...)
exclusives = append(exclusives, ex...)
// If we removed any exclusives, then we can start over.
if len(done) > 0 {
continue Loop
}
// TODO: We could try and replace our combinatorial
// exclusive solver with a real SAT solver algorithm.
if !AllowRecursion || len(exclusives) > RecursionInvariantLimit {
logf("%s: %d solved, %d unsolved, and %d exclusives left", Name, len(solved), len(equalities), len(exclusives))
for i, eq := range equalities {
logf("%s: (%d) equality: %s", Name, i, eq)
}
for i, ex := range exclusives {
logf("%s: (%d) exclusive: %s", Name, i, ex)
}
// these can be very slow, so try to avoid them
return nil, fmt.Errorf("only recursive solutions left")
}
// let's try each combination, one at a time...
for i, ex := range exclusivesProduct(exclusives) { // [][]interfaces.Invariant
logf("%s: exclusive(%d):\n%+v", Name, i, ex)
@@ -605,6 +731,7 @@ Loop:
recursiveInvariants := []interfaces.Invariant{}
recursiveInvariants = append(recursiveInvariants, partialSolutions...)
recursiveInvariants = append(recursiveInvariants, ex...)
// FIXME: implement RecursionDepthLimit
logf("%s: recursing...", Name)
solution, err := SimpleInvariantSolver(recursiveInvariants, expected, logf)
if err != nil {
@@ -617,7 +744,7 @@ Loop:
}
// TODO: print ambiguity
return nil, fmt.Errorf("can't unify, no equalities were consumed, we're ambiguous")
return nil, ErrAmbiguous
}
// delete used equalities, in reverse order to preserve indexing!
for i := len(used) - 1; i >= 0; i-- {