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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

90
lang/funcs/operator_polyfunc.go
View File

@@ -33,8 +33,9 @@ const (
// starts with an underscore so that it cannot be used from the lexer.
OperatorFuncName = "_operator"
// operatorArgName is the edge and arg name used for the function's operator.
operatorArgName = "x" // something short and arbitrary
// operatorArgName is the edge and arg name used for the function's
// operator.
operatorArgName = "op" // something short and arbitrary
)
func init() {
@@ -356,6 +357,7 @@ func RegisterOperator(operator string, fn *types.FuncValue) {
panic(fmt.Sprintf("can't use `%s` as an argName for operator `%s` with type `%+v`", x, operator, fn.T))
}
// yes this limits the arg max to 24 (`x`) including operator
// if the operator is `x`...
if s := util.NumToAlpha(i); x != s {
panic(fmt.Sprintf("arg for operator `%s` (index `%d`) should be named `%s`, not `%s`", operator, i, s, x))
}
@@ -387,8 +389,7 @@ func LookupOperator(operator string, size int) ([]*types.Type, error) {
}
for _, fn := range fns {
typ := addOperatorArg(fn.T) // add in the `operatorArgName` arg
typ = unlabelOperatorArgNames(typ) // label in standard a..b..c
typ := addOperatorArg(fn.T) // add in the `operatorArgName` arg
if size >= 0 && len(typ.Ord) != size {
continue
@@ -414,7 +415,7 @@ type OperatorPolyFunc struct {
// argNames returns the maximum list of possible argNames. This can be truncated
// if needed. The first arg name is the operator.
func (obj *OperatorPolyFunc) argNames() []string {
func (obj *OperatorPolyFunc) argNames() ([]string, error) {
// we could just do this statically, but i did it dynamically so that I
// wouldn't ever have to remember to update this list...
max := 0
@@ -434,12 +435,12 @@ func (obj *OperatorPolyFunc) argNames() []string {
for i := 0; i < max; i++ {
s := util.NumToAlpha(i)
if s == operatorArgName {
panic(fmt.Sprintf("can't use `%s` as arg name", operatorArgName))
return nil, fmt.Errorf("can't use `%s` as arg name", operatorArgName)
}
args = append(args, s)
}
return args
return args, nil
}
// findFunc tries to find the first available registered operator function that
@@ -458,6 +459,18 @@ func (obj *OperatorPolyFunc) findFunc(operator string) *types.FuncValue {
return nil
}
// ArgGen returns the Nth arg name for this function.
func (obj *OperatorPolyFunc) ArgGen(index int) (string, error) {
seq, err := obj.argNames()
if err != nil {
return "", err
}
if l := len(seq); index >= l {
return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
}
return seq[index], nil
}
// Polymorphisms returns the list of possible function signatures available for
// this static polymorphic function. It relies on type and value hints to limit
// the number of returned possibilities.
@@ -507,11 +520,9 @@ func (obj *OperatorPolyFunc) Polymorphisms(partialType *types.Type, partialValue
// specific statically typed version. It is usually run after Unify completes,
// and must be run before Info() and any of the other Func interface methods are
// used. This function is idempotent, as long as the arg isn't changed between
// runs. It typically re-labels the input arg names to match what is actually
// used.
// runs.
func (obj *OperatorPolyFunc) Build(typ *types.Type) error {
// typ is the KindFunc signature we're trying to build...
if len(typ.Ord) < 1 {
return fmt.Errorf("the operator function needs at least 1 arg")
}
@@ -519,11 +530,7 @@ func (obj *OperatorPolyFunc) Build(typ *types.Type) error {
return fmt.Errorf("return type of function must be specified")
}
t, err := obj.relabelOperatorArgNames(typ)
if err != nil {
return fmt.Errorf("could not build function from type: %+v", typ)
}
obj.Type = t // func type
obj.Type = typ // func type
return nil
}
@@ -635,59 +642,6 @@ func (obj *OperatorPolyFunc) Close() error {
return nil
}
// relabelOperatorArgNames relabels the input type of kind func with arg names
// that match the expected ones for this operator (which are all standardized).
func (obj *OperatorPolyFunc) relabelOperatorArgNames(typ *types.Type) (*types.Type, error) {
if typ == nil {
return nil, fmt.Errorf("cannot re-label missing type")
}
if typ.Kind != types.KindFunc {
return nil, fmt.Errorf("specified type must be a func kind")
}
argNames := obj.argNames() // correct arg names...
if l := len(argNames); len(typ.Ord) > l {
return nil, fmt.Errorf("did not expect more than %d args", l)
}
m := make(map[string]*types.Type)
ord := []string{}
for pos, x := range typ.Ord { // function args in order
name := argNames[pos] // new arg name
m[name] = typ.Map[x] // n-th type stored with new arg name
ord = append(ord, name)
}
return &types.Type{
Kind: types.KindFunc,
Map: m,
Ord: ord,
Out: typ.Out,
}, nil
}
// unlabelOperatorArgNames unlabels the input type of kind func with arg names
// that match the default ones for all functions (which are all standardized).
func unlabelOperatorArgNames(typ *types.Type) *types.Type {
if typ == nil {
return nil
}
m := make(map[string]*types.Type)
ord := []string{}
for pos, x := range typ.Ord { // function args in order
name := util.NumToAlpha(pos) // default (unspecified) naming
m[name] = typ.Map[x] // n-th type stored with new arg name
ord = append(ord, name)
}
return &types.Type{
Kind: types.KindFunc,
Map: m,
Ord: ord,
Out: typ.Out,
}
}
// removeOperatorArg returns a copy of the input KindFunc type, without the
// operator arg which specifies which operator we're using. It *is* idempotent.
func removeOperatorArg(typ *types.Type) *types.Type {