func (np NodeProcedure) Apply(e *Evaluator, argVals *gol.NodeList) (gol.Node, error) {
if argVals.Len() != np.Args.Len() {
return nil, gol.NodeErrorf(argVals, "Arg mismatch")
}
f := gol.Frame{}
z := np.Args.Zip(argVals)
err := z.Foreach(func(n gol.Node) error {
pair, ok := n.(*gol.NodePair)
if !ok {
return gol.NodeErrorf(argVals, "Internal error - zip returns non-pair")
}
id := pair.Car
val := pair.Cdr
idStr := id.String()
f[idStr] = val
return nil
})
if err != nil {
return nil, err
}
oldEnv := e.Env
defer func() {
e.Env = oldEnv
}()
e.Env = np.Env.WithFrame(f)
value, err := e.Eval(np.Body)
return value, err
}
func (gb *GolangBackend) compileList(nl *gol.NodeList) (string, error) {
if nl.Len() == 0 {
return "", gol.NodeErrorf(nl, "empty application")
}
switch fst := nl.First().(type) {
case *gol.NodeIdentifier:
return gb.compileFuncCall(fst, nl.Rest())
case *gol.NodeLambda:
return gb.compileLambdaApplication(fst, nl.Rest())
default:
return "", fmt.Errorf("Non-applicable in head position: %T", fst)
}
}
func (e *Evaluator) Apply(nl *gol.NodeList) (gol.Node, error) {
if nl.Len() == 0 {
return nil, gol.NodeErrorf(nl, "Empty application")
}
applicable, ok := nl.First().(NodeApplicable)
if !ok {
return nil, gol.NodeErrorf(nl, "Can't evaluate list with non-applicable head: %T [%s]", nl.First(), nl)
}
node, err := applicable.Apply(e, nl.Rest())
if err != nil {
return nil, err
}
return node, nil
}
func (gb *GolangBackend) compileLambdaApplication(nl *gol.NodeLambda, vals *gol.NodeList) (string, error) {
bindings := make(map[string]gol.Node)
args := nl.Args
if args.Len() != vals.Len() {
return "", fmt.Errorf("Wrong number of args for lambda. [%s] != [%s]",
args.String(), vals.String())
}
for vals.Len() > 0 {
id := args.First().String()
bindings[id] = vals.First()
vals = vals.Rest()
args = args.Rest()
}
letForLambda := &gol.NodeLet{
// NodeList: nl.NodeList,
Bindings: bindings,
Body: nl.Body,
}
lambdaVarType, ok := nl.Type().(*typ.Var)
if !ok {
// Not an error if it's a functype, but we assign vars to all nodes....
return "", fmt.Errorf("Odd - not a var, instead a %T: %s\n", nl.Type(), nl.Type())
}
lambdaType, err := lambdaVarType.Lookup()
if err != nil {
return "", fmt.Errorf("Can't look up lambda var: %s [%T]\n", lambdaVarType, lambdaVarType)
}
funcType, ok := lambdaType.(typ.Func)
if !ok {
return "", fmt.Errorf("Lambda doesn't have function type: %s [%T]\n", nl.Type(), nl.Type())
}
letForLambda.NodeList = gol.NewNodeListType(funcType.Result)
return gb.compileLet(letForLambda)
}