lang: funcs: core: iter: Add map iterator function part2

This adds the Unify method to our map function and also switches the arg
order because I decided it would look nicer. Completely untested.

lang/funcs/core/iter/map_func.go

@@ -23,6 +23,7 @@ import (
 	"github.com/purpleidea/mgmt/lang/funcs"
 	"github.com/purpleidea/mgmt/lang/interfaces"
 	"github.com/purpleidea/mgmt/lang/types"
+	"github.com/purpleidea/mgmt/util"
 	"github.com/purpleidea/mgmt/util/errwrap"
 )
 
@@ -32,14 +33,18 @@ func init() {
 }
 
 const (
-	argNameFunction = "function"
 	argNameInputs   = "inputs"
+	argNameFunction = "function"
 )
 
 // MapFunc is the standard map iterator function that applies a function to each
 // element in a list. It returns a list with the same number of elements as the
 // input list. There is no requirement that the element output type be the same
-// as the input element type.
+// as the input element type. This implements the signature:
+// `func(inputs []T1, function func(T1) T2) []T2` instead of the alternate with
+// the two input args swapped, because while the latter is more common with
+// languages that support partial function application, the former variant that
+// we implemented is much more readable when using an inline lambda.
 // TODO: should we extend this to support iterating over map's and structs, or
 // should that be a different function? I think a different function is best.
 type MapFunc struct {
@@ -49,8 +54,8 @@ type MapFunc struct {
 	init *interfaces.Init
 	last types.Value // last value received to use for diff
 
-	function func([]types.Value) (types.Value, error)
 	inputs   types.Value
+	function func([]types.Value) (types.Value, error)
 
 	result types.Value // last calculated output
 
@@ -59,17 +64,291 @@ type MapFunc struct {
 
 // ArgGen returns the Nth arg name for this function.
 func (obj *MapFunc) ArgGen(index int) (string, error) {
-	seq := []string{argNameFunction, argNameInputs}
+	seq := []string{argNameInputs, argNameFunction} // inverted for pretty!
 	if l := len(seq); index >= l {
 		return "", fmt.Errorf("index %d exceeds arg length of %d", index, l)
 	}
 	return seq[index], nil
 }
 
+// Unify returns the list of invariants that this func produces.
+func (obj *MapFunc) Unify(expr interfaces.Expr) ([]interfaces.Invariant, error) {
+	var invariants []interfaces.Invariant
+	var invar interfaces.Invariant
+
+	// func(inputs []T1, function func(T1) T2) []T2
+
+	inputsName, err := obj.ArgGen(0)
+	if err != nil {
+		return nil, err
+	}
+	functionName, err := obj.ArgGen(1)
+	if err != nil {
+		return nil, err
+	}
+
+	dummyArgList := &interfaces.ExprAny{} // corresponds to the input list
+	dummyArgFunc := &interfaces.ExprAny{} // corresponds to the input func
+	dummyOutList := &interfaces.ExprAny{} // corresponds to the output list
+
+	// full function
+	mapped := make(map[string]interfaces.Expr)
+	ordered := []string{inputsName, functionName}
+	mapped[inputsName] = dummyArgList
+	mapped[functionName] = dummyArgFunc
+
+	invar = &interfaces.EqualityWrapFuncInvariant{
+		Expr1:    expr, // maps directly to us!
+		Expr2Map: mapped,
+		Expr2Ord: ordered,
+		Expr2Out: dummyOutList,
+	}
+	invariants = append(invariants, invar)
+
+	// generator function
+	fn := func(fnInvariants []interfaces.Invariant, solved map[interfaces.Expr]*types.Type) ([]interfaces.Invariant, error) {
+		for _, invariant := range fnInvariants {
+			// search for this special type of invariant
+			cfavInvar, ok := invariant.(*interfaces.CallFuncArgsValueInvariant)
+			if !ok {
+				continue
+			}
+			// did we find the mapping from us to ExprCall ?
+			if cfavInvar.Func != expr {
+				continue
+			}
+			// cfavInvar.Expr is the ExprCall! (the return pointer)
+			// cfavInvar.Args are the args that ExprCall uses!
+			if l := len(cfavInvar.Args); l != 2 {
+				return nil, fmt.Errorf("unable to build function with %d args", l)
+			}
+			// we must have exactly two args
+
+			var invariants []interfaces.Invariant
+			var invar interfaces.Invariant
+
+			t1Expr := &interfaces.ExprAny{} // corresponds to the t1 type
+			t2Expr := &interfaces.ExprAny{} // corresponds to the t2 type
+
+			// add the relationship to the returned value
+			invar = &interfaces.EqualityInvariant{
+				Expr1: cfavInvar.Expr,
+				Expr2: dummyOutList,
+			}
+			invariants = append(invariants, invar)
+
+			// add the relationships to the called args
+			invar = &interfaces.EqualityInvariant{
+				Expr1: cfavInvar.Args[0],
+				Expr2: dummyArgList,
+			}
+			invariants = append(invariants, invar)
+
+			invar = &interfaces.EqualityInvariant{
+				Expr1: cfavInvar.Args[1],
+				Expr2: dummyArgFunc,
+			}
+			invariants = append(invariants, invar)
+
+			var t1, t2 *types.Type                       // as seen in our sig's
+			var foundArgName string = util.NumToAlpha(0) // XXX: is this a hack?
+
+			// validateArg0 checks: inputs []T1
+			validateArg0 := func(typ *types.Type) error {
+				if typ == nil { // unknown so far
+					return nil
+				}
+				if typ.Kind != types.KindList {
+					return fmt.Errorf("input type must be of kind list")
+				}
+				if typ.Val == nil { // TODO: is this okay to add?
+					return nil // unknown so far
+				}
+				if t1 == nil { // t1 is not yet known, so done!
+					t1 = typ.Val // learn!
+					return nil
+				}
+				//if err := typ.Val.Cmp(t1); err != nil {
+				//	return errwrap.Wrapf(err, "input type was inconsistent")
+				//}
+				//return nil
+				return errwrap.Wrapf(typ.Val.Cmp(t1), "input type was inconsistent")
+			}
+
+			// validateArg1 checks: func(T1) T2
+			validateArg1 := func(typ *types.Type) error {
+				if typ == nil { // unknown so far
+					return nil
+				}
+				if typ.Kind != types.KindFunc {
+					return fmt.Errorf("input type must be of kind func")
+				}
+				if len(typ.Map) != 1 || len(typ.Ord) != 1 {
+					return fmt.Errorf("input type func must have only one input arg")
+				}
+				arg, exists := typ.Map[typ.Ord[0]]
+				if !exists {
+					// programming error
+					return fmt.Errorf("input type func first arg is missing")
+				}
+
+				if t1 != nil {
+					if err := arg.Cmp(t1); err != nil {
+						return errwrap.Wrapf(err, "input type func arg was inconsistent")
+					}
+				}
+				if t2 != nil {
+					if err := typ.Out.Cmp(t2); err != nil {
+						return errwrap.Wrapf(err, "input type func output was inconsistent")
+					}
+				}
+
+				// in case they weren't set already
+				t1 = arg
+				t2 = typ.Out
+				foundArgName = typ.Ord[0] // we found a name!
+				return nil
+			}
+
+			if typ, err := cfavInvar.Args[0].Type(); err == nil { // is it known?
+				// this sets t1 and t2 on success if it learned
+				if err := validateArg0(typ); err != nil {
+					return nil, errwrap.Wrapf(err, "first input arg type is inconsistent")
+				}
+			}
+			if typ, exists := solved[cfavInvar.Args[0]]; exists { // alternate way to lookup type
+				// this sets t1 and t2 on success if it learned
+				if err := validateArg0(typ); err != nil {
+					return nil, errwrap.Wrapf(err, "first input arg type is inconsistent")
+				}
+			}
+			// XXX: since we might not yet have association to this
+			// expression (dummyArgList) yet, we could consider
+			// returning some of the invariants and a new generator
+			// and hoping we get a hit on this one the next time.
+			if typ, exists := solved[dummyArgList]; exists { // alternate way to lookup type
+				// this sets t1 and t2 on success if it learned
+				if err := validateArg0(typ); err != nil {
+					return nil, errwrap.Wrapf(err, "first input arg type is inconsistent")
+				}
+			}
+
+			if typ, err := cfavInvar.Args[1].Type(); err == nil { // is it known?
+				// this sets t1 and t2 on success if it learned
+				if err := validateArg1(typ); err != nil {
+					return nil, errwrap.Wrapf(err, "second input arg type is inconsistent")
+				}
+			}
+			if typ, exists := solved[cfavInvar.Args[1]]; exists { // alternate way to lookup type
+				// this sets t1 and t2 on success if it learned
+				if err := validateArg1(typ); err != nil {
+					return nil, errwrap.Wrapf(err, "second input arg type is inconsistent")
+				}
+			}
+			// XXX: since we might not yet have association to this
+			// expression (dummyArgFunc) yet, we could consider
+			// returning some of the invariants and a new generator
+			// and hoping we get a hit on this one the next time.
+			if typ, exists := solved[dummyArgFunc]; exists { // alternate way to lookup type
+				// this sets t1 and t2 on success if it learned
+				if err := validateArg1(typ); err != nil {
+					return nil, errwrap.Wrapf(err, "second input arg type is inconsistent")
+				}
+			}
+
+			// XXX: look for t1 and t2 in other places?
+
+			if t1 != nil {
+				invar = &interfaces.EqualsInvariant{
+					Expr: t1Expr,
+					Type: t1,
+				}
+				invariants = append(invariants, invar)
+
+				invar = &interfaces.EqualityWrapListInvariant{
+					Expr1:    cfavInvar.Args[0],
+					Expr2Val: t1Expr,
+				}
+				invariants = append(invariants, invar)
+				// we already have the mapping, but add both in
+				// case we need to solve these from either side
+				invar = &interfaces.EqualityWrapListInvariant{
+					Expr1:    dummyArgList,
+					Expr2Val: t1Expr,
+				}
+				invariants = append(invariants, invar)
+			}
+
+			if t1 != nil && t2 != nil {
+				argName := foundArgName // XXX: is this a hack?
+				mapped := make(map[string]interfaces.Expr)
+				ordered := []string{argName}
+				mapped[argName] = t1Expr
+
+				invar = &interfaces.EqualityWrapFuncInvariant{
+					Expr1:    dummyArgFunc,
+					Expr2Map: mapped,
+					Expr2Ord: ordered,
+					Expr2Out: t2Expr,
+				}
+				invariants = append(invariants, invar)
+			}
+
+			// note, currently, we can't learn t2 without t1
+			if t2 != nil {
+				invar = &interfaces.EqualsInvariant{
+					Expr: t2Expr,
+					Type: t2,
+				}
+				invariants = append(invariants, invar)
+
+				invar = &interfaces.EqualityWrapListInvariant{
+					Expr1:    dummyOutList,
+					Expr2Val: t2Expr,
+				}
+				invariants = append(invariants, invar)
+				// we already have the mapping, but add both in
+				// case we need to solve these from either side
+				invar = &interfaces.EqualityWrapListInvariant{
+					Expr1:    cfavInvar.Expr,
+					Expr2Val: t2Expr,
+				}
+				invariants = append(invariants, invar)
+			}
+
+			// We need to require this knowledge to continue!
+			if t1 == nil || t2 == nil {
+				return nil, fmt.Errorf("not enough known about function signature")
+			}
+
+			// TODO: do we return this relationship with ExprCall?
+			invar = &interfaces.EqualityWrapCallInvariant{
+				// TODO: should Expr1 and Expr2 be reversed???
+				Expr1: cfavInvar.Expr,
+				//Expr2Func: cfavInvar.Func, // same as below
+				Expr2Func: expr,
+			}
+			invariants = append(invariants, invar)
+
+			// TODO: are there any other invariants we should build?
+			return invariants, nil // generator return
+		}
+		// We couldn't tell the solver anything it didn't already know!
+		return nil, fmt.Errorf("couldn't generate new invariants")
+	}
+	invar = &interfaces.GeneratorInvariant{
+		Func: fn,
+	}
+	invariants = append(invariants, invar)
+
+	return invariants, 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.
 func (obj *MapFunc) Polymorphisms(partialType *types.Type, partialValues []types.Value) ([]*types.Type, error) {
+	// XXX: double check that this works with `func([]int, func(int) str) []str` (when types change!)
 	// TODO: look at partialValues to gleam type information?
 	if partialType == nil {
 		return nil, fmt.Errorf("zero type information given")
@@ -100,22 +379,22 @@ func (obj *MapFunc) Polymorphisms(partialType *types.Type, partialValues []types
 			return nil, fmt.Errorf("must have two args in func")
 		}
 
-		if tInputs, exists := partialType.Map[ord[1]]; exists && tInputs != nil {
+		if tInputs, exists := partialType.Map[ord[0]]; exists && tInputs != nil {
 			if tInputs.Kind != types.KindList {
-				return nil, fmt.Errorf("second input arg must be of kind list")
+				return nil, fmt.Errorf("first input arg must be of kind list")
 			}
 			t1 = tInputs.Val // found (if not nil)
 		}
 
-		if tFunction, exists := partialType.Map[ord[0]]; exists && tFunction != nil {
+		if tFunction, exists := partialType.Map[ord[1]]; exists && tFunction != nil {
 			if tFunction.Kind != types.KindFunc {
-				return nil, fmt.Errorf("first input arg must be a func")
+				return nil, fmt.Errorf("second input arg must be a func")
 			}
 
 			fOrd := tFunction.Ord
 			if fMap := tFunction.Map; fMap != nil {
 				if len(fOrd) != 1 {
-					return nil, fmt.Errorf("first input arg func, must have only one arg")
+					return nil, fmt.Errorf("second input arg func, must have only one arg")
 				}
 				if fIn, exists := fMap[fOrd[0]]; exists && fIn != nil {
 					if err := fIn.Cmp(t1); t1 != nil && err != nil {
@@ -127,7 +406,7 @@ func (obj *MapFunc) Polymorphisms(partialType *types.Type, partialValues []types
 
 			if fOut := tFunction.Out; fOut != nil {
 				if err := fOut.Cmp(t2); t2 != nil && err != nil {
-					return nil, errwrap.Wrapf(err, "first arg function out type is inconsistent")
+					return nil, errwrap.Wrapf(err, "second arg function out type is inconsistent")
 				}
 				t2 = fOut // found
 			}
@@ -140,7 +419,7 @@ func (obj *MapFunc) Polymorphisms(partialType *types.Type, partialValues []types
 	tI := types.NewType(fmt.Sprintf("[]%s", t1.String())) // in
 	tO := types.NewType(fmt.Sprintf("[]%s", t2.String())) // out
 	tF := types.NewType(fmt.Sprintf("func(%s) %s", t1.String(), t2.String()))
-	s := fmt.Sprintf("func(%s %s, %s %s) %s", argNameFunction, tF, argNameInputs, tI, tO)
+	s := fmt.Sprintf("func(%s %s, %s %s) %s", argNameInputs, tI, argNameFunction, tF, tO)
 	typ := types.NewType(s) // yay!
 
 	// TODO: type check that the partialValues are compatible
@@ -166,20 +445,20 @@ func (obj *MapFunc) Build(typ *types.Type) error {
 		return fmt.Errorf("the map is nil")
 	}
 
-	tFunction, exists := typ.Map[typ.Ord[0]]
-	if !exists || tFunction == nil {
+	tInputs, exists := typ.Map[typ.Ord[0]]
+	if !exists || tInputs == nil {
 		return fmt.Errorf("first argument was missing")
 	}
-	tInputs, exists := typ.Map[typ.Ord[1]]
-	if !exists || tInputs == nil {
+	tFunction, exists := typ.Map[typ.Ord[1]]
+	if !exists || tFunction == nil {
 		return fmt.Errorf("second argument was missing")
 	}
 
-	if tFunction.Kind != types.KindFunc {
-		return fmt.Errorf("first argument must be of kind func")
-	}
 	if tInputs.Kind != types.KindList {
-		return fmt.Errorf("second argument must be of kind list")
+		return fmt.Errorf("first argument must be of kind list")
+	}
+	if tFunction.Kind != types.KindFunc {
+		return fmt.Errorf("second argument must be of kind func")
 	}
 
 	if typ.Out == nil {
@@ -242,7 +521,7 @@ func (obj *MapFunc) Info() *interfaces.Info {
 	// type of 1st arg (the function)
 	tF := types.NewType(fmt.Sprintf("func(%s) %s", tIi.String(), tOi.String()))
 
-	s := fmt.Sprintf("func(%s %s, %s %s) %s", argNameFunction, tF, argNameInputs, tI, tO)
+	s := fmt.Sprintf("func(%s %s, %s %s) %s", argNameInputs, tI, argNameFunction, tF, tO)
 	typ := types.NewType(s) // yay!
 
 	return &interfaces.Info{

lang/interpret_test/TestAstFunc2/map-iterator0.output

@@ -0,0 +1 @@
+Vertex: test[out1: [1 2 3 4 5]]

lang/interpret_test/TestAstFunc2/map-iterator0/main.mcl

@@ -0,0 +1,13 @@
+import "iter"
+
+$fn = func($x) { # notable because concrete type is fn(t1) t2, where t1 != t2
+	len($x)
+}
+
+$in1 = ["a", "bb", "ccc", "dddd", "eeeee",]
+
+$out1 = iter.xmap($in1, $fn) # XXX: change to map
+
+$t1 = template("out1: {{ . }}", $out1)
+
+test $t1 {}

lang/interpret_test/TestAstFunc2/map-iterator1/main.mcl

@@ -11,10 +11,10 @@ $fn = func($x) {
 $in1 = [5, 4, 3, 2, 1,]
 $in2 = ["a", "b", "c", "d", "e",]
 
-$out1 = iter.xmap($fn, $in1) # XXX: change to map
-$out2 = iter.xmap($fn, $in2) # XXX: change to map
-$out3 = iterxmap($fn, $in1) # XXX: change to map
-$out4 = iterxmap($fn, $in2) # XXX: change to map
+$out1 = iter.xmap($in1, $fn) # XXX: change to map
+$out2 = iter.xmap($in2, $fn) # XXX: change to map
+$out3 = iterxmap($in1, $fn) # XXX: change to map
+$out4 = iterxmap($in2, $fn) # XXX: change to map
 
 $t1 = template("out1: {{ . }}", $out1)
 $t2 = template("out2: {{ . }}", $out2)

lang/interpret_test/TestAstFunc2/map-iterator2/main.mcl

@@ -6,7 +6,7 @@ $fn = func($x) { # ignore arg
 
 $in = [5, 4, 3, 2, 1,]
 
-$out = iter.xmap($fn, $in) # XXX: change to map
+$out = iter.xmap($in, $fn) # XXX: change to map
 
 $t = template("out: {{ . }}", $out)
 

lang/interpret_test/TestAstFunc2/map-iterator3.output

@@ -0,0 +1 @@
+Vertex: test[out: [1 2 3 4 5]]

lang/interpret_test/TestAstFunc2/map-iterator3/main.mcl

@@ -0,0 +1,13 @@
+import "iter"
+
+$fn = func($x) { # type changes from str to int
+	len($x)
+}
+
+$in = ["a", "bb", "ccc", "dddd", "eeeee",]
+
+$out = iter.xmap($in, $fn) # XXX: change to map
+
+$t = template("out: {{ . }}", $out)
+
+test $t {}

lang/interpret_test/TestAstFunc2/map-iterator4.output

@@ -0,0 +1 @@
+Vertex: test[out: [1 2 3 4 5]]

lang/interpret_test/TestAstFunc2/map-iterator4/main.mcl

@@ -0,0 +1,13 @@
+import "iter"
+
+$in = ["a", "bb", "ccc", "dddd", "eeeee",]
+
+# the inline lambda format is more readable with the func as the second arg
+$out = iter.xmap($in, func($x) {
+	len($x)
+
+}) # XXX: change to map
+
+$t = template("out: {{ . }}", $out)
+
+test $t {}