func div(s *scheme.Scope, args []scheme.Sexpr) (scheme.Sexpr, error) {
if len(args) != 2 {
return nil, scheme.ProcError("/ requires exactly 2 arguments")
}
if !scheme.IsNumber(args[0]) || !scheme.IsNumber(args[1]) {
return nil, scheme.ProcError("/ requires all number arguments")
}
left := args[0].(*scheme.Number).Val
right := args[1].(*scheme.Number).Val
return scheme.NumberFromInt(left / right), nil
}
func plus(s *scheme.Scope, args []scheme.Sexpr) (scheme.Sexpr, error) {
if len(args) < 2 {
return nil, scheme.ProcError("+ requires at least 2 arguments")
}
var sum int64 = 0
for _, a := range args {
if scheme.IsNumber(a) {
sum += a.(*scheme.Number).Val
} else {
return nil, scheme.ProcError("+ requires all number arguments")
}
}
return scheme.NumberFromInt(sum), nil
}
func mul(s *scheme.Scope, args []scheme.Sexpr) (scheme.Sexpr, error) {
if len(args) < 2 {
return nil, scheme.ProcError("* requires at least 2 arguments")
}
var product int64 = 1
for _, a := range args {
if scheme.IsNumber(a) {
product *= a.(*scheme.Number).Val
} else {
return nil, scheme.ProcError("* requires all number arguments")
}
}
return scheme.NumberFromInt(product), nil
}
func parseAtom(tok lexer.Token) scheme.Sexpr {
if isString(tok) {
return scheme.StringFromString(string(tok.Val[1 : len(tok.Val)-1]))
} else if isBoolean(tok) {
return scheme.BooleanFromString(tok.Val)
} else if isNumber(tok) {
n, _ := strconv.ParseInt(tok.Val, 10, 64)
return scheme.NumberFromInt(n)
} else if isChar(tok) {
n, _ := strconv.ParseInt(tok.Val[3:], 16, 64)
return scheme.CharFromRune(rune(n))
}
return scheme.SymbolFromString(tok.Val)
}