lang: core, funcs, types: Add ctx to simple func

Plumb through the standard context.Context so that a function can be
cancelled if someone requests this. It makes it less awkward to write
simple functions that might depend on io or network access.

lang/core/concat_func.go

@@ -30,6 +30,8 @@
 package core
 
 import (
+	"context"
+
 	"github.com/purpleidea/mgmt/lang/funcs"
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
@@ -48,7 +50,7 @@ func init() {
 }
 
 // Concat concatenates two strings together.
-func Concat(input []types.Value) (types.Value, error) {
+func Concat(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: input[0].Str() + input[1].Str(),
 	}, nil

lang/core/convert/format_bool.go

@@ -30,6 +30,7 @@
 package convert
 
 import (
+	"context"
 	"strconv"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -45,7 +46,7 @@ func init() {
 
 // FormatBool converts a boolean to a string representation that can be consumed
 // by ParseBool. This value will be `"true"` or `"false"`.
-func FormatBool(input []types.Value) (types.Value, error) {
+func FormatBool(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: strconv.FormatBool(input[0].Bool()),
 	}, nil

lang/core/convert/parse_bool.go

@@ -30,6 +30,7 @@
 package convert
 
 import (
+	"context"
 	"fmt"
 	"strconv"
 
@@ -48,7 +49,7 @@ func init() {
 // it an invalid value. Valid values match what is accepted by the golang
 // strconv.ParseBool function. It's recommended to use the strings `true` or
 // `false` if you are undecided about what string representation to choose.
-func ParseBool(input []types.Value) (types.Value, error) {
+func ParseBool(ctx context.Context, input []types.Value) (types.Value, error) {
 	s := input[0].Str()
 	b, err := strconv.ParseBool(s)
 	if err != nil {

lang/core/convert/to_float.go

@@ -30,6 +30,8 @@
 package convert
 
 import (
+	"context"
+
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
 )
@@ -42,7 +44,7 @@ func init() {
 }
 
 // ToFloat converts an integer to a float.
-func ToFloat(input []types.Value) (types.Value, error) {
+func ToFloat(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.FloatValue{
 		V: float64(input[0].Int()),
 	}, nil

lang/core/convert/to_float_test.go

@@ -30,13 +30,14 @@
 package convert
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
 )
 
 func testToFloat(t *testing.T, input int64, expected float64) {
-	got, err := ToFloat([]types.Value{&types.IntValue{V: input}})
+	got, err := ToFloat(context.Background(), []types.Value{&types.IntValue{V: input}})
 	if err != nil {
 		t.Error(err)
 		return

lang/core/convert/to_int.go

@@ -30,6 +30,8 @@
 package convert
 
 import (
+	"context"
+
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
 )
@@ -42,7 +44,7 @@ func init() {
 }
 
 // ToInt converts a float to an integer.
-func ToInt(input []types.Value) (types.Value, error) {
+func ToInt(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.IntValue{
 		V: int64(input[0].Float()),
 	}, nil

lang/core/convert/to_int_test.go

@@ -30,6 +30,7 @@
 package convert
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
@@ -37,7 +38,7 @@ import (
 
 func testToInt(t *testing.T, input float64, expected int64) {
 
-	got, err := ToInt([]types.Value{&types.FloatValue{V: input}})
+	got, err := ToInt(context.Background(), []types.Value{&types.FloatValue{V: input}})
 	if err != nil {
 		t.Error(err)
 		return

lang/core/convert/to_str.go

@@ -30,6 +30,7 @@
 package convert
 
 import (
+	"context"
 	"strconv"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -49,7 +50,7 @@ func init() {
 }
 
 // IntToStr converts an integer to a string.
-func IntToStr(input []types.Value) (types.Value, error) {
+func IntToStr(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: strconv.Itoa(int(input[0].Int())),
 	}, nil

lang/core/datetime/format_func.go

@@ -30,6 +30,7 @@
 package coredatetime
 
 import (
+	"context"
 	"fmt"
 	"time"
 
@@ -48,7 +49,7 @@ func init() {
 // has to be defined like specified by the golang "time" package. The time is
 // the number of seconds since the epoch, and matches what comes from our Now
 // function. Golang documentation: https://golang.org/pkg/time/#Time.Format
-func Format(input []types.Value) (types.Value, error) {
+func Format(ctx context.Context, input []types.Value) (types.Value, error) {
 	epochDelta := input[0].Int()
 	if epochDelta < 0 {
 		return nil, fmt.Errorf("epoch delta must be positive")

lang/core/datetime/format_func_test.go

@@ -32,6 +32,7 @@
 package coredatetime
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
@@ -41,7 +42,7 @@ func TestFormat(t *testing.T) {
 	inputVal := &types.IntValue{V: 1443158163}
 	inputFormat := &types.StrValue{V: "2006"}
 
-	val, err := Format([]types.Value{inputVal, inputFormat})
+	val, err := Format(context.Background(), []types.Value{inputVal, inputFormat})
 	if err != nil {
 		t.Error(err)
 	}

lang/core/datetime/hour_func.go

@@ -30,6 +30,7 @@
 package coredatetime
 
 import (
+	"context"
 	"fmt"
 	"time"
 
@@ -47,7 +48,7 @@ func init() {
 // Hour returns the hour of the day corresponding to the input time. The time is
 // the number of seconds since the epoch, and matches what comes from our Now
 // function.
-func Hour(input []types.Value) (types.Value, error) {
+func Hour(ctx context.Context, input []types.Value) (types.Value, error) {
 	epochDelta := input[0].Int()
 	if epochDelta < 0 {
 		return nil, fmt.Errorf("epoch delta must be positive")

lang/core/datetime/print_func.go

@@ -30,6 +30,7 @@
 package coredatetime
 
 import (
+	"context"
 	"fmt"
 	"time"
 
@@ -41,7 +42,7 @@ func init() {
 	// FIXME: consider renaming this to printf, and add in a format string?
 	simple.ModuleRegister(ModuleName, "print", &types.FuncValue{
 		T: types.NewType("func(a int) str"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			epochDelta := input[0].Int()
 			if epochDelta < 0 {
 				return nil, fmt.Errorf("epoch delta must be positive")

lang/core/datetime/weekday_func.go

@@ -30,6 +30,7 @@
 package coredatetime
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"time"
@@ -48,7 +49,7 @@ func init() {
 // Weekday returns the lowercased day of the week corresponding to the input
 // time. The time is the number of seconds since the epoch, and matches what
 // comes from our Now function.
-func Weekday(input []types.Value) (types.Value, error) {
+func Weekday(ctx context.Context, input []types.Value) (types.Value, error) {
 	epochDelta := input[0].Int()
 	if epochDelta < 0 {
 		return nil, fmt.Errorf("epoch delta must be positive")

lang/core/embedded/provisioner/provisioner.go

@@ -418,11 +418,14 @@ func (obj *provisioner) Register(moduleName string) error {
 	// Build a few separately...
 	simple.ModuleRegister(moduleName, "cli_password", &types.FuncValue{
 		T: types.NewType("func() str"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			if obj.localArgs == nil {
 				// programming error
 				return nil, fmt.Errorf("could not convert/access our struct")
 			}
+
+			// TODO: plumb through the password lookup here instead?
+
 			//localArgs := *obj.localArgs // optional
 			return &types.StrValue{
 				V: obj.password,

lang/core/example/answer_func.go

@@ -30,6 +30,8 @@
 package coreexample
 
 import (
+	"context"
+
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
 )
@@ -40,7 +42,7 @@ const Answer = 42
 func init() {
 	simple.ModuleRegister(ModuleName, "answer", &types.FuncValue{
 		T: types.NewType("func() int"),
-		V: func([]types.Value) (types.Value, error) {
+		V: func(context.Context, []types.Value) (types.Value, error) {
 			return &types.IntValue{V: Answer}, nil
 		},
 	})

lang/core/example/errorbool_func.go

@@ -30,6 +30,7 @@
 package coreexample
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -39,7 +40,7 @@ import (
 func init() {
 	simple.ModuleRegister(ModuleName, "errorbool", &types.FuncValue{
 		T: types.NewType("func(a bool) str"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			if input[0].Bool() {
 				return nil, fmt.Errorf("we errored on request")
 			}

lang/core/example/int2str_func.go

@@ -30,6 +30,7 @@
 package coreexample
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -39,7 +40,7 @@ import (
 func init() {
 	simple.ModuleRegister(ModuleName, "int2str", &types.FuncValue{
 		T: types.NewType("func(a int) str"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.StrValue{
 				V: fmt.Sprintf("%d", input[0].Int()),
 			}, nil

lang/core/example/nested/hello_func.go

@@ -30,6 +30,8 @@
 package corenested
 
 import (
+	"context"
+
 	coreexample "github.com/purpleidea/mgmt/lang/core/example"
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
@@ -43,7 +45,7 @@ func init() {
 }
 
 // Hello returns some string. This is just to test nesting.
-func Hello(input []types.Value) (types.Value, error) {
+func Hello(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: "Hello!",
 	}, nil

lang/core/example/plus_func.go

@@ -30,6 +30,8 @@
 package coreexample
 
 import (
+	"context"
+
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
 )
@@ -42,7 +44,7 @@ func init() {
 }
 
 // Plus returns y + z.
-func Plus(input []types.Value) (types.Value, error) {
+func Plus(ctx context.Context, input []types.Value) (types.Value, error) {
 	y, z := input[0].Str(), input[1].Str()
 	return &types.StrValue{
 		V: y + z,

lang/core/example/str2int_func.go

@@ -30,6 +30,7 @@
 package coreexample
 
 import (
+	"context"
 	"strconv"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -39,7 +40,7 @@ import (
 func init() {
 	simple.ModuleRegister(ModuleName, "str2int", &types.FuncValue{
 		T: types.NewType("func(a str) int"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			var i int64
 			if val, err := strconv.ParseInt(input[0].Str(), 10, 64); err == nil {
 				i = val

lang/core/iter/map_func.go

@@ -766,7 +766,7 @@ func (obj *MapFunc) replaceSubGraph(subgraphInput interfaces.Func) error {
 	outputListFunc := structs.SimpleFnToDirectFunc(
 		"mapOutputList",
 		&types.FuncValue{
-			V: func(args []types.Value) (types.Value, error) {
+			V: func(_ context.Context, args []types.Value) (types.Value, error) {
 				listValue := &types.ListValue{
 					V: args,
 					T: obj.outputListType,
@@ -788,7 +788,7 @@ func (obj *MapFunc) replaceSubGraph(subgraphInput interfaces.Func) error {
 		inputElemFunc := structs.SimpleFnToDirectFunc(
 			fmt.Sprintf("mapInputElem[%d]", i),
 			&types.FuncValue{
-				V: func(args []types.Value) (types.Value, error) {
+				V: func(_ context.Context, args []types.Value) (types.Value, error) {
 					if len(args) != 1 {
 						return nil, fmt.Errorf("inputElemFunc: expected a single argument")
 					}

lang/core/len_func.go

@@ -30,6 +30,7 @@
 package core
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
@@ -56,7 +57,7 @@ func init() {
 
 // Len returns the number of elements in a list or the number of key pairs in a
 // map. It can operate on either of these types.
-func Len(input []types.Value) (types.Value, error) {
+func Len(ctx context.Context, input []types.Value) (types.Value, error) {
 	var length int
 	switch k := input[0].Type().Kind; k {
 	case types.KindStr:

lang/core/math/fortytwo_func.go

@@ -30,6 +30,7 @@
 package coremath
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
@@ -57,8 +58,8 @@ func init() {
 // in a sig field, like how we demonstrate in the implementation of FortyTwo. If
 // the API doesn't change, then this is an example of how to build this as a
 // wrapper.
-func fortyTwo(sig *types.Type) func([]types.Value) (types.Value, error) {
-	return func(input []types.Value) (types.Value, error) {
+func fortyTwo(sig *types.Type) func(context.Context, []types.Value) (types.Value, error) {
+	return func(ctx context.Context, input []types.Value) (types.Value, error) {
 		return FortyTwo(sig, input)
 	}
 }

lang/core/math/minus1_func.go

@@ -30,6 +30,8 @@
 package coremath
 
 import (
+	"context"
+
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
 	"github.com/purpleidea/mgmt/lang/types"
 )
@@ -42,7 +44,7 @@ func init() {
 }
 
 // Minus1 takes an int and subtracts one from it.
-func Minus1(input []types.Value) (types.Value, error) {
+func Minus1(ctx context.Context, input []types.Value) (types.Value, error) {
 	// TODO: check for overflow
 	return &types.IntValue{
 		V: input[0].Int() - 1,

lang/core/math/mod_func.go

@@ -30,6 +30,7 @@
 package coremath
 
 import (
+	"context"
 	"fmt"
 	"math"
 
@@ -54,7 +55,7 @@ func init() {
 // both of KindInt or both of KindFloat, and it will return the same kind. If
 // you pass in a divisor of zero, this will error, eg: mod(x, 0) = NaN.
 // TODO: consider returning zero instead of erroring?
-func Mod(input []types.Value) (types.Value, error) {
+func Mod(ctx context.Context, input []types.Value) (types.Value, error) {
 	var x, y float64
 	var float bool
 	k := input[0].Type().Kind

lang/core/math/pow_func.go

@@ -30,6 +30,7 @@
 package coremath
 
 import (
+	"context"
 	"fmt"
 	"math"
 
@@ -45,7 +46,7 @@ func init() {
 }
 
 // Pow returns x ^ y, the base-x exponential of y.
-func Pow(input []types.Value) (types.Value, error) {
+func Pow(ctx context.Context, input []types.Value) (types.Value, error) {
 	x, y := input[0].Float(), input[1].Float()
 	// FIXME: check for overflow
 	z := math.Pow(x, y)

lang/core/math/sqrt_func.go

@@ -30,6 +30,7 @@
 package coremath
 
 import (
+	"context"
 	"fmt"
 	"math"
 
@@ -45,7 +46,7 @@ func init() {
 }
 
 // Sqrt returns sqrt(x), the square root of x.
-func Sqrt(input []types.Value) (types.Value, error) {
+func Sqrt(ctx context.Context, input []types.Value) (types.Value, error) {
 	x := input[0].Float()
 	y := math.Sqrt(x)
 	if math.IsNaN(y) {

lang/core/math/sqrt_func_test.go

@@ -30,6 +30,7 @@
 package coremath
 
 import (
+	"context"
 	"fmt"
 	"math"
 	"testing"
@@ -40,7 +41,7 @@ import (
 func testSqrtSuccess(input, sqrt float64) error {
 	inputVal := &types.FloatValue{V: input}
 
-	val, err := Sqrt([]types.Value{inputVal})
+	val, err := Sqrt(context.Background(), []types.Value{inputVal})
 	if err != nil {
 		return err
 	}
@@ -52,7 +53,7 @@ func testSqrtSuccess(input, sqrt float64) error {
 
 func testSqrtError(input float64) error {
 	inputVal := &types.FloatValue{V: input}
-	_, err := Sqrt([]types.Value{inputVal})
+	_, err := Sqrt(context.Background(), []types.Value{inputVal})
 	if err == nil {
 		return fmt.Errorf("expected error for input %f, got nil", input)
 	}

lang/core/net/cidr_to_ip_func.go

@@ -30,6 +30,7 @@
 package corenet
 
 import (
+	"context"
 	"net"
 	"strings"
 
@@ -45,7 +46,7 @@ func init() {
 }
 
 // CidrToIP returns the IP from a CIDR address
-func CidrToIP(input []types.Value) (types.Value, error) {
+func CidrToIP(ctx context.Context, input []types.Value) (types.Value, error) {
 	cidr := input[0].Str()
 	ip, _, err := net.ParseCIDR(strings.TrimSpace(cidr))
 	if err != nil {

lang/core/net/cidr_to_ip_func_test.go

@@ -30,6 +30,7 @@
 package corenet
 
 import (
+	"context"
 	"fmt"
 	"testing"
 
@@ -61,7 +62,7 @@ func TestCidrToIP(t *testing.T) {
 	for _, ts := range cidrtests {
 		test := ts
 		t.Run(test.name, func(t *testing.T) {
-			output, err := CidrToIP([]types.Value{&types.StrValue{V: test.input}})
+			output, err := CidrToIP(context.Background(), []types.Value{&types.StrValue{V: test.input}})
 			expectedStr := &types.StrValue{V: test.expected}
 
 			if test.err != nil && err.Error() != test.err.Error() {

lang/core/net/macfmt_func.go

@@ -30,6 +30,7 @@
 package corenet
 
 import (
+	"context"
 	"fmt"
 	"net"
 	"strings"
@@ -51,7 +52,7 @@ func init() {
 
 // MacFmt takes a MAC address with hyphens and converts it to a format with
 // colons.
-func MacFmt(input []types.Value) (types.Value, error) {
+func MacFmt(ctx context.Context, input []types.Value) (types.Value, error) {
 	mac := input[0].Str()
 
 	// Check if the MAC address is valid.
@@ -70,7 +71,7 @@ func MacFmt(input []types.Value) (types.Value, error) {
 
 // OldMacFmt takes a MAC address with colons and converts it to a format with
 // hyphens. This is the old deprecated style that nobody likes.
-func OldMacFmt(input []types.Value) (types.Value, error) {
+func OldMacFmt(ctx context.Context, input []types.Value) (types.Value, error) {
 	mac := input[0].Str()
 
 	// Check if the MAC address is valid.

lang/core/net/macfmt_func_test.go

@@ -30,6 +30,7 @@
 package corenet
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
@@ -51,7 +52,7 @@ func TestMacFmt(t *testing.T) {
 	for _, tt := range tests {
 		tt := tt
 		t.Run(tt.name, func(t *testing.T) {
-			m, err := MacFmt([]types.Value{&types.StrValue{V: tt.in}})
+			m, err := MacFmt(context.Background(), []types.Value{&types.StrValue{V: tt.in}})
 			if (err != nil) != tt.wantErr {
 				t.Errorf("func MacFmt() error = %v, wantErr %v", err, tt.wantErr)
 				return
@@ -81,7 +82,7 @@ func TestOldMacFmt(t *testing.T) {
 	for _, tt := range tests {
 		tt := tt
 		t.Run(tt.name, func(t *testing.T) {
-			m, err := OldMacFmt([]types.Value{&types.StrValue{V: tt.in}})
+			m, err := OldMacFmt(context.Background(), []types.Value{&types.StrValue{V: tt.in}})
 			if (err != nil) != tt.wantErr {
 				t.Errorf("func MacFmt() error = %v, wantErr %v", err, tt.wantErr)
 				return

lang/core/os/args_func.go

@@ -30,6 +30,7 @@
 package coreos
 
 import (
+	"context"
 	"os"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -47,7 +48,7 @@ func init() {
 // return different values depending on how this is deployed, so don't expect a
 // result on your deploy client to behave the same as a server receiving code.
 // FIXME: Sanitize any command-line secrets we might pass in by cli.
-func Args([]types.Value) (types.Value, error) {
+func Args(context.Context, []types.Value) (types.Value, error) {
 	values := []types.Value{}
 	for _, s := range os.Args {
 		values = append(values, &types.StrValue{V: s})

lang/core/os/distro_func.go

@@ -30,6 +30,7 @@
 package coreos
 
 import (
+	"context"
 	"fmt"
 	"strings"
 
@@ -51,7 +52,7 @@ func init() {
 // ParseDistroUID parses a distro UID into its component values. If it cannot
 // parse correctly, all the struct fields have the zero values.
 // NOTE: The UID pattern is subject to change.
-func ParseDistroUID(input []types.Value) (types.Value, error) {
+func ParseDistroUID(ctx context.Context, input []types.Value) (types.Value, error) {
 	fn := func(distro, version, arch string) (types.Value, error) {
 		st := types.NewStruct(types.NewType(structDistroUID))
 		if err := st.Set("distro", &types.StrValue{V: distro}); err != nil {

lang/core/os/family_func.go

@@ -30,6 +30,7 @@
 package coreos
 
 import (
+	"context"
 	"os"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -54,8 +55,9 @@ func init() {
 
 // IsDebian detects if the os family is debian.
 // TODO: Detect OS changes.
-func IsDebian(input []types.Value) (types.Value, error) {
+func IsDebian(ctx context.Context, input []types.Value) (types.Value, error) {
 	exists := true
+	// TODO: use ctx around io operations
 	_, err := os.Stat("/etc/debian_version")
 	if os.IsNotExist(err) {
 		exists = false
@@ -67,8 +69,9 @@ func IsDebian(input []types.Value) (types.Value, error) {
 
 // IsRedHat detects if the os family is redhat.
 // TODO: Detect OS changes.
-func IsRedHat(input []types.Value) (types.Value, error) {
+func IsRedHat(ctx context.Context, input []types.Value) (types.Value, error) {
 	exists := true
+	// TODO: use ctx around io operations
 	_, err := os.Stat("/etc/redhat-release")
 	if os.IsNotExist(err) {
 		exists = false
@@ -80,8 +83,9 @@ func IsRedHat(input []types.Value) (types.Value, error) {
 
 // IsArchLinux detects if the os family is archlinux.
 // TODO: Detect OS changes.
-func IsArchLinux(input []types.Value) (types.Value, error) {
+func IsArchLinux(ctx context.Context, input []types.Value) (types.Value, error) {
 	exists := true
+	// TODO: use ctx around io operations
 	_, err := os.Stat("/etc/arch-release")
 	if os.IsNotExist(err) {
 		exists = false

lang/core/panic_func.go

@@ -30,6 +30,7 @@
 package core
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simplepoly"
@@ -52,7 +53,7 @@ func init() {
 // Panic returns an error when it receives a non-empty string or a true boolean.
 // The error should cause the function engine to shutdown. If there's no error,
 // it returns false.
-func Panic(input []types.Value) (types.Value, error) {
+func Panic(ctx context.Context, input []types.Value) (types.Value, error) {
 	switch k := input[0].Type().Kind; k {
 	case types.KindBool:
 		if input[0].Bool() {

lang/core/regexp/match_func.go

@@ -30,6 +30,7 @@
 package coreregexp
 
 import (
+	"context"
 	"regexp"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -45,7 +46,7 @@ func init() {
 }
 
 // Match matches whether a string matches the regexp pattern.
-func Match(input []types.Value) (types.Value, error) {
+func Match(ctx context.Context, input []types.Value) (types.Value, error) {
 	pattern := input[0].Str()
 	s := input[1].Str()
 

lang/core/regexp/match_func_test.go

@@ -30,6 +30,7 @@
 package coreregexp
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
@@ -76,7 +77,7 @@ func TestMatch0(t *testing.T) {
 	for i, x := range values {
 		pattern := &types.StrValue{V: x.pattern}
 		s := &types.StrValue{V: x.s}
-		val, err := Match([]types.Value{pattern, s})
+		val, err := Match(context.Background(), []types.Value{pattern, s})
 		if err != nil {
 			t.Errorf("test index %d failed with: %+v", i, err)
 		}

lang/core/strings/split_func.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"strings"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -45,7 +46,7 @@ func init() {
 
 // Split splits the input string using the separator and returns the segments as
 // a list.
-func Split(input []types.Value) (types.Value, error) {
+func Split(ctx context.Context, input []types.Value) (types.Value, error) {
 	str, sep := input[0].Str(), input[1].Str()
 
 	segments := strings.Split(str, sep)

lang/core/strings/split_func_test.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"fmt"
 	"testing"
 
@@ -40,7 +41,7 @@ import (
 func testSplit(input, sep string, output []string) error {
 	inputVal, sepVal := &types.StrValue{V: input}, &types.StrValue{V: sep}
 
-	val, err := Split([]types.Value{inputVal, sepVal})
+	val, err := Split(context.Background(), []types.Value{inputVal, sepVal})
 	if err != nil {
 		return err
 	}

lang/core/strings/to_lower_func.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"strings"
 
 	"github.com/purpleidea/mgmt/lang/funcs/simple"
@@ -44,7 +45,7 @@ func init() {
 }
 
 // ToLower turns a string to lowercase.
-func ToLower(input []types.Value) (types.Value, error) {
+func ToLower(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: strings.ToLower(input[0].Str()),
 	}, nil

lang/core/strings/to_lower_func_test.go

@@ -30,6 +30,7 @@
 package corestrings
 
 import (
+	"context"
 	"testing"
 
 	"github.com/purpleidea/mgmt/lang/types"
@@ -37,7 +38,7 @@ import (
 
 func testToLower(t *testing.T, input, expected string) {
 	inputStr := &types.StrValue{V: input}
-	value, err := ToLower([]types.Value{inputStr})
+	value, err := ToLower(context.Background(), []types.Value{inputStr})
 	if err != nil {
 		t.Error(err)
 		return

lang/core/sys/env_func.go

@@ -30,6 +30,7 @@
 package coresys
 
 import (
+	"context"
 	"os"
 	"strings"
 
@@ -58,7 +59,7 @@ func init() {
 
 // GetEnv gets environment variable by name or returns empty string if non
 // existing.
-func GetEnv(input []types.Value) (types.Value, error) {
+func GetEnv(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: os.Getenv(input[0].Str()),
 	}, nil
@@ -66,7 +67,7 @@ func GetEnv(input []types.Value) (types.Value, error) {
 
 // DefaultEnv gets environment variable by name or returns default if non
 // existing.
-func DefaultEnv(input []types.Value) (types.Value, error) {
+func DefaultEnv(ctx context.Context, input []types.Value) (types.Value, error) {
 	value, exists := os.LookupEnv(input[0].Str())
 	if !exists {
 		value = input[1].Str()
@@ -77,7 +78,7 @@ func DefaultEnv(input []types.Value) (types.Value, error) {
 }
 
 // HasEnv returns true if environment variable exists.
-func HasEnv(input []types.Value) (types.Value, error) {
+func HasEnv(ctx context.Context, input []types.Value) (types.Value, error) {
 	_, exists := os.LookupEnv(input[0].Str())
 	return &types.BoolValue{
 		V: exists,
@@ -85,7 +86,7 @@ func HasEnv(input []types.Value) (types.Value, error) {
 }
 
 // Env returns a map of all keys and their values.
-func Env(input []types.Value) (types.Value, error) {
+func Env(ctx context.Context, input []types.Value) (types.Value, error) {
 	environ := make(map[types.Value]types.Value)
 	for _, keyval := range os.Environ() {
 		if i := strings.IndexRune(keyval, '='); i != -1 {

lang/core/template_func.go

@@ -390,7 +390,7 @@ func (obj *TemplateFunc) Init(init *interfaces.Init) error {
 }
 
 // run runs a template and returns the result.
-func (obj *TemplateFunc) run(templateText string, vars types.Value) (string, error) {
+func (obj *TemplateFunc) run(ctx context.Context, templateText string, vars types.Value) (string, error) {
 	// see: https://golang.org/pkg/text/template/#FuncMap for more info
 	// note: we can override any other functions by adding them here...
 	funcMap := map[string]interface{}{
@@ -425,7 +425,7 @@ func (obj *TemplateFunc) run(templateText string, vars types.Value) (string, err
 		// parameter types. Functions meant to apply to arguments of
 		// arbitrary type can use parameters of type interface{} or of
 		// type reflect.Value.
-		f, err := wrap(name, fn) // wrap it so that it meets API expectations
+		f, err := wrap(ctx, name, fn) // wrap it so that it meets API expectations
 		if err != nil {
 			obj.init.Logf("warning, skipping function named: `%s`, err: %v", name, err)
 			continue
@@ -538,7 +538,7 @@ func (obj *TemplateFunc) Stream(ctx context.Context) error {
 				vars = nil
 			}
 
-			result, err := obj.run(tmpl, vars)
+			result, err := obj.run(ctx, tmpl, vars)
 			if err != nil {
 				return err // no errwrap needed b/c helper func
 			}
@@ -585,7 +585,7 @@ func safename(name string) string {
 // function API with what is expected from the reflection API. It returns a
 // version that includes the optional second error return value so that our
 // functions can return errors without causing a panic.
-func wrap(name string, fn *types.FuncValue) (_ interface{}, reterr error) {
+func wrap(ctx context.Context, name string, fn *types.FuncValue) (_ interface{}, reterr error) {
 	defer func() {
 		// catch unhandled panics
 		if r := recover(); r != nil {
@@ -633,8 +633,8 @@ func wrap(name string, fn *types.FuncValue) (_ interface{}, reterr error) {
 			innerArgs = append(innerArgs, v)
 		}
 
-		result, err := fn.Call(innerArgs) // call it
-		if err != nil {                   // function errored :(
+		result, err := fn.Call(ctx, innerArgs) // call it
+		if err != nil {                        // function errored :(
 			// errwrap is a better way to report errors, if allowed!
 			r := reflect.ValueOf(errwrap.Wrapf(err, "function `%s` errored", name))
 			if !r.Type().ConvertibleTo(errorType) { // for fun!

lang/core/test/oneinstance_fact.go

@@ -123,7 +123,7 @@ func init() {
 
 	simple.ModuleRegister(ModuleName, OneInstanceBFuncName, &types.FuncValue{
 		T: types.NewType("func() str"),
-		V: func([]types.Value) (types.Value, error) {
+		V: func(context.Context, []types.Value) (types.Value, error) {
 			oneInstanceBMutex.Lock()
 			if oneInstanceBFlag {
 				panic("should not get called twice")
@@ -135,7 +135,7 @@ func init() {
 	})
 	simple.ModuleRegister(ModuleName, OneInstanceDFuncName, &types.FuncValue{
 		T: types.NewType("func() str"),
-		V: func([]types.Value) (types.Value, error) {
+		V: func(context.Context, []types.Value) (types.Value, error) {
 			oneInstanceDMutex.Lock()
 			if oneInstanceDFlag {
 				panic("should not get called twice")
@@ -147,7 +147,7 @@ func init() {
 	})
 	simple.ModuleRegister(ModuleName, OneInstanceFFuncName, &types.FuncValue{
 		T: types.NewType("func() str"),
-		V: func([]types.Value) (types.Value, error) {
+		V: func(context.Context, []types.Value) (types.Value, error) {
 			oneInstanceFMutex.Lock()
 			if oneInstanceFFlag {
 				panic("should not get called twice")
@@ -159,7 +159,7 @@ func init() {
 	})
 	simple.ModuleRegister(ModuleName, OneInstanceHFuncName, &types.FuncValue{
 		T: types.NewType("func() str"),
-		V: func([]types.Value) (types.Value, error) {
+		V: func(context.Context, []types.Value) (types.Value, error) {
 			oneInstanceHMutex.Lock()
 			if oneInstanceHFlag {
 				panic("should not get called twice")

lang/funcs/funcgen/fixtures/func_base.tpl

@@ -30,6 +30,7 @@
 package core
 
 import (
+	"context"
 	"testpkg"
 
 	"github.com/purpleidea/mgmt/lang/funcs/funcgen/util"
@@ -65,25 +66,25 @@ func init() {
 
 }
 
-func TestpkgAllKind(input []types.Value) (types.Value, error) {
+func TestpkgAllKind(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.FloatValue{
 		V: testpkg.AllKind(input[0].Int(), input[1].Str()),
 	}, nil
 }
 
-func TestpkgToUpper(input []types.Value) (types.Value, error) {
+func TestpkgToUpper(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: testpkg.ToUpper(input[0].Str()),
 	}, nil
 }
 
-func TestpkgMax(input []types.Value) (types.Value, error) {
+func TestpkgMax(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.FloatValue{
 		V: testpkg.Max(input[0].Float(), input[1].Float()),
 	}, nil
 }
 
-func TestpkgWithError(input []types.Value) (types.Value, error) {
+func TestpkgWithError(ctx context.Context, input []types.Value) (types.Value, error) {
 	v, err := testpkg.WithError(input[0].Str())
 	if err != nil {
 		return nil, err
@@ -93,13 +94,13 @@ func TestpkgWithError(input []types.Value) (types.Value, error) {
 	}, nil
 }
 
-func TestpkgWithInt(input []types.Value) (types.Value, error) {
+func TestpkgWithInt(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: testpkg.WithInt(input[0].Float(), int(input[1].Int()), input[2].Int(), int(input[3].Int()), int(input[4].Int()), input[5].Bool(), input[6].Str()),
 	}, nil
 }
 
-func TestpkgSuperByte(input []types.Value) (types.Value, error) {
+func TestpkgSuperByte(ctx context.Context, input []types.Value) (types.Value, error) {
 	return &types.StrValue{
 		V: string(testpkg.SuperByte([]byte(input[0].Str()), input[1].Str())),
 	}, nil

lang/funcs/funcgen/templates/generated_funcs.go.tpl

@@ -30,6 +30,7 @@
 package core
 
 import (
+	"context"
 {{ range $i, $func := .Packages }}	{{ if not (eq .Alias "") }}{{.Alias}} {{end}}"{{.Name}}"
 {{ end }}
 	"github.com/purpleidea/mgmt/lang/funcs/funcgen/util"
@@ -45,7 +46,7 @@ func init() {
 {{ end }}
 }
 {{ range $i, $func := .Functions }}
-{{$func.Help}}func {{$func.InternalName}}(input []types.Value) (types.Value, error) {
+{{$func.Help}}func {{$func.InternalName}}(ctx context.Context, input []types.Value) (types.Value, error) {
 {{- if $func.Errorful }}
 	v, err := {{ if not (eq $func.GolangPackage.Alias "") }}{{$func.GolangPackage.Alias}}{{else}}{{$func.GolangPackage.Name}}{{end}}.{{$func.GolangFunc}}({{$func.MakeGolangArgs}})
 	if err != nil {

lang/funcs/operator_func.go

@@ -55,7 +55,7 @@ func init() {
 	// concatenation
 	RegisterOperator("+", &types.FuncValue{
 		T: types.NewType("func(a str, b str) str"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.StrValue{
 				V: input[0].Str() + input[1].Str(),
 			}, nil
@@ -64,7 +64,7 @@ func init() {
 	// addition
 	RegisterOperator("+", &types.FuncValue{
 		T: types.NewType("func(a int, b int) int"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			//if l := len(input); l != 2 {
 			//	return nil, fmt.Errorf("expected two inputs, got: %d", l)
 			//}
@@ -77,7 +77,7 @@ func init() {
 	// floating-point addition
 	RegisterOperator("+", &types.FuncValue{
 		T: types.NewType("func(a float, b float) float"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.FloatValue{
 				V: input[0].Float() + input[1].Float(),
 			}, nil
@@ -87,7 +87,7 @@ func init() {
 	// subtraction
 	RegisterOperator("-", &types.FuncValue{
 		T: types.NewType("func(a int, b int) int"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.IntValue{
 				V: input[0].Int() - input[1].Int(),
 			}, nil
@@ -96,7 +96,7 @@ func init() {
 	// floating-point subtraction
 	RegisterOperator("-", &types.FuncValue{
 		T: types.NewType("func(a float, b float) float"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.FloatValue{
 				V: input[0].Float() - input[1].Float(),
 			}, nil
@@ -106,7 +106,7 @@ func init() {
 	// multiplication
 	RegisterOperator("*", &types.FuncValue{
 		T: types.NewType("func(a int, b int) int"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// FIXME: check for overflow?
 			return &types.IntValue{
 				V: input[0].Int() * input[1].Int(),
@@ -116,7 +116,7 @@ func init() {
 	// floating-point multiplication
 	RegisterOperator("*", &types.FuncValue{
 		T: types.NewType("func(a float, b float) float"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.FloatValue{
 				V: input[0].Float() * input[1].Float(),
 			}, nil
@@ -127,7 +127,7 @@ func init() {
 	// division
 	RegisterOperator("/", &types.FuncValue{
 		T: types.NewType("func(a int, b int) float"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			divisor := input[1].Int()
 			if divisor == 0 {
 				return nil, fmt.Errorf("can't divide by zero")
@@ -140,7 +140,7 @@ func init() {
 	// floating-point division
 	RegisterOperator("/", &types.FuncValue{
 		T: types.NewType("func(a float, b float) float"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			divisor := input[1].Float()
 			if divisor == 0.0 {
 				return nil, fmt.Errorf("can't divide by zero")
@@ -154,7 +154,7 @@ func init() {
 	// string equality
 	RegisterOperator("==", &types.FuncValue{
 		T: types.NewType("func(a str, b str) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Str() == input[1].Str(),
 			}, nil
@@ -163,7 +163,7 @@ func init() {
 	// bool equality
 	RegisterOperator("==", &types.FuncValue{
 		T: types.NewType("func(a bool, b bool) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Bool() == input[1].Bool(),
 			}, nil
@@ -172,7 +172,7 @@ func init() {
 	// int equality
 	RegisterOperator("==", &types.FuncValue{
 		T: types.NewType("func(a int, b int) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Int() == input[1].Int(),
 			}, nil
@@ -181,7 +181,7 @@ func init() {
 	// floating-point equality
 	RegisterOperator("==", &types.FuncValue{
 		T: types.NewType("func(a float, b float) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// TODO: should we do an epsilon check?
 			return &types.BoolValue{
 				V: input[0].Float() == input[1].Float(),
@@ -192,7 +192,7 @@ func init() {
 	// string in-equality
 	RegisterOperator("!=", &types.FuncValue{
 		T: types.NewType("func(a str, b str) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Str() != input[1].Str(),
 			}, nil
@@ -201,7 +201,7 @@ func init() {
 	// bool in-equality
 	RegisterOperator("!=", &types.FuncValue{
 		T: types.NewType("func(a bool, b bool) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Bool() != input[1].Bool(),
 			}, nil
@@ -210,7 +210,7 @@ func init() {
 	// int in-equality
 	RegisterOperator("!=", &types.FuncValue{
 		T: types.NewType("func(a int, b int) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Int() != input[1].Int(),
 			}, nil
@@ -219,7 +219,7 @@ func init() {
 	// floating-point in-equality
 	RegisterOperator("!=", &types.FuncValue{
 		T: types.NewType("func(a float, b float) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// TODO: should we do an epsilon check?
 			return &types.BoolValue{
 				V: input[0].Float() != input[1].Float(),
@@ -230,7 +230,7 @@ func init() {
 	// less-than
 	RegisterOperator("<", &types.FuncValue{
 		T: types.NewType("func(a int, b int) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Int() < input[1].Int(),
 			}, nil
@@ -239,7 +239,7 @@ func init() {
 	// floating-point less-than
 	RegisterOperator("<", &types.FuncValue{
 		T: types.NewType("func(a float, b float) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// TODO: should we do an epsilon check?
 			return &types.BoolValue{
 				V: input[0].Float() < input[1].Float(),
@@ -249,7 +249,7 @@ func init() {
 	// greater-than
 	RegisterOperator(">", &types.FuncValue{
 		T: types.NewType("func(a int, b int) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Int() > input[1].Int(),
 			}, nil
@@ -258,7 +258,7 @@ func init() {
 	// floating-point greater-than
 	RegisterOperator(">", &types.FuncValue{
 		T: types.NewType("func(a float, b float) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// TODO: should we do an epsilon check?
 			return &types.BoolValue{
 				V: input[0].Float() > input[1].Float(),
@@ -268,7 +268,7 @@ func init() {
 	// less-than-equal
 	RegisterOperator("<=", &types.FuncValue{
 		T: types.NewType("func(a int, b int) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Int() <= input[1].Int(),
 			}, nil
@@ -277,7 +277,7 @@ func init() {
 	// floating-point less-than-equal
 	RegisterOperator("<=", &types.FuncValue{
 		T: types.NewType("func(a float, b float) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// TODO: should we do an epsilon check?
 			return &types.BoolValue{
 				V: input[0].Float() <= input[1].Float(),
@@ -287,7 +287,7 @@ func init() {
 	// greater-than-equal
 	RegisterOperator(">=", &types.FuncValue{
 		T: types.NewType("func(a int, b int) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Int() >= input[1].Int(),
 			}, nil
@@ -296,7 +296,7 @@ func init() {
 	// floating-point greater-than-equal
 	RegisterOperator(">=", &types.FuncValue{
 		T: types.NewType("func(a float, b float) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			// TODO: should we do an epsilon check?
 			return &types.BoolValue{
 				V: input[0].Float() >= input[1].Float(),
@@ -309,7 +309,7 @@ func init() {
 	// short-circuit operators, and does it matter?
 	RegisterOperator("and", &types.FuncValue{
 		T: types.NewType("func(a bool, b bool) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Bool() && input[1].Bool(),
 			}, nil
@@ -318,7 +318,7 @@ func init() {
 	// logical or
 	RegisterOperator("or", &types.FuncValue{
 		T: types.NewType("func(a bool, b bool) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: input[0].Bool() || input[1].Bool(),
 			}, nil
@@ -328,7 +328,7 @@ func init() {
 	// logical not (unary operator)
 	RegisterOperator("not", &types.FuncValue{
 		T: types.NewType("func(a bool) bool"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.BoolValue{
 				V: !input[0].Bool(),
 			}, nil
@@ -338,7 +338,7 @@ func init() {
 	// pi operator (this is an easter egg to demo a zero arg operator)
 	RegisterOperator("π", &types.FuncValue{
 		T: types.NewType("func() float"),
-		V: func(input []types.Value) (types.Value, error) {
+		V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 			return &types.FloatValue{
 				V: math.Pi,
 			}, nil
@@ -938,7 +938,7 @@ func (obj *OperatorFunc) Stream(ctx context.Context) error {
 			lastOp = op
 
 			var result types.Value
-			result, err := fn.Call(args) // run the function
+			result, err := fn.Call(ctx, args) // run the function
 			if err != nil {
 				return errwrap.Wrapf(err, "problem running function")
 			}

lang/funcs/simple/simple.go

@@ -173,7 +173,7 @@ func (obj *WrappedFunc) Stream(ctx context.Context) error {
 				values = append(values, x)
 			}
 
-			result, err := obj.Fn.Call(values) // (Value, error)
+			result, err := obj.Fn.Call(ctx, values) // (Value, error)
 			if err != nil {
 				return errwrap.Wrapf(err, "simple function errored")
 			}
@@ -244,7 +244,7 @@ func StructRegister(moduleName string, args interface{}) error {
 
 		ModuleRegister(moduleName, name, &types.FuncValue{
 			T: types.NewType(fmt.Sprintf("func() %s", typed.String())),
-			V: func(input []types.Value) (types.Value, error) {
+			V: func(ctx context.Context, input []types.Value) (types.Value, error) {
 				//if args == nil {
 				//	// programming error
 				//	return nil, fmt.Errorf("could not convert/access our struct")

lang/funcs/simplepoly/simplepoly.go

@@ -602,7 +602,7 @@ func (obj *WrappedFunc) Stream(ctx context.Context) error {
 			if obj.init.Debug {
 				obj.init.Logf("Calling function with: %+v", values)
 			}
-			result, err := obj.fn.Call(values) // (Value, error)
+			result, err := obj.fn.Call(ctx, values) // (Value, error)
 			if err != nil {
 				if obj.init.Debug {
 					obj.init.Logf("Function returned error: %+v", err)

lang/types/value.go

@@ -30,6 +30,7 @@
 package types
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"net"
@@ -230,7 +231,7 @@ func ValueOf(v reflect.Value) (Value, error) {
 			return nil, fmt.Errorf("cannot only represent functions with one output value")
 		}
 
-		f := func(args []Value) (Value, error) {
+		f := func(ctx context.Context, args []Value) (Value, error) {
 			in := []reflect.Value{}
 			for _, x := range args {
 				// TODO: should we build this method instead?
@@ -239,6 +240,7 @@ func ValueOf(v reflect.Value) (Value, error) {
 				in = append(in, v)
 			}
 
+			// FIXME: can we pass in ctx ?
 			// FIXME: can we trap panic's ?
 			out := value.Call(in) // []reflect.Value
 			if len(out) != 1 {    // TODO: panic, b/c already checked in TypeOf?
@@ -1207,7 +1209,7 @@ func (obj *StructValue) Lookup(k string) (value Value, exists bool) {
 // Func nodes.
 type FuncValue struct {
 	Base
-	V func([]Value) (Value, error)
+	V func(context.Context, []Value) (Value, error)
 	T *Type // contains ordered field types, arg names are a bonus part
 }
 
@@ -1217,7 +1219,7 @@ func NewFunc(t *Type) *FuncValue {
 	if t.Kind != KindFunc {
 		return nil // sanity check
 	}
-	v := func([]Value) (Value, error) {
+	v := func(context.Context, []Value) (Value, error) {
 		// You were not supposed to call the temporary function, you
 		// were supposed to replace it with a real implementation!
 		return nil, fmt.Errorf("nil function")
@@ -1301,7 +1303,7 @@ func (obj *FuncValue) Value() interface{} {
 // Call runs the function value and returns its result. It returns an error if
 // something goes wrong during execution, and panic's if you call this with
 // inappropriate input types, or if it returns an inappropriate output type.
-func (obj *FuncValue) Call(args []Value) (Value, error) {
+func (obj *FuncValue) Call(ctx context.Context, args []Value) (Value, error) {
 	// cmp input args type to obj.T
 	length := len(obj.T.Ord)
 	if length != len(args) {
@@ -1313,7 +1315,7 @@ func (obj *FuncValue) Call(args []Value) (Value, error) {
 		}
 	}
 
-	result, err := obj.V(args) // call it
+	result, err := obj.V(ctx, args) // call it
 	if result == nil {
 		if err == nil {
 			return nil, fmt.Errorf("function returned nil result")