/
plum.go
373 lines (354 loc) · 7.92 KB
/
plum.go
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package main
import (
"errors"
"fmt"
"os"
"strings"
)
import (
"github.com/sllt/plum/constants"
"github.com/sllt/plum/core"
. "github.com/sllt/plum/env"
"github.com/sllt/plum/printer"
"github.com/sllt/plum/reader"
"github.com/sllt/plum/readline"
. "github.com/sllt/plum/types"
)
// read
func READ(str string) (PlumType, error) {
return reader.Read_str(str)
}
// eval
func is_pair(x PlumType) bool {
slc, e := GetSlice(x)
if e != nil {
return false
}
return len(slc) > 0
}
func quasiquote(ast PlumType) PlumType {
if !is_pair(ast) {
return List{[]PlumType{Symbol{"quote"}, ast}, nil}
} else {
slc, _ := GetSlice(ast)
a0 := slc[0]
if Symbol_Q(a0) && (a0.(Symbol).Val == "unquote") {
return slc[1]
} else if is_pair(a0) {
slc0, _ := GetSlice(a0)
a00 := slc0[0]
if Symbol_Q(a00) && (a00.(Symbol).Val == "splice-unquote") {
return List{[]PlumType{Symbol{"concat"},
slc0[1],
quasiquote(List{slc[1:], nil})}, nil}
}
}
return List{[]PlumType{Symbol{"cons"},
quasiquote(a0),
quasiquote(List{slc[1:], nil})}, nil}
}
}
func is_macro_call(ast PlumType, env EnvType) bool {
if List_Q(ast) {
slc, _ := GetSlice(ast)
a0 := slc[0]
if Symbol_Q(a0) && env.Find(a0.(Symbol)) != nil {
mac, e := env.Get(a0.(Symbol))
if e != nil {
return false
}
if PlumFunc_Q(mac) {
return mac.(PlumFunc).GetMacro()
}
}
}
return false
}
func macroexpand(ast PlumType, env EnvType) (PlumType, error) {
var mac PlumType
var e error
for is_macro_call(ast, env) {
slc, _ := GetSlice(ast)
a0 := slc[0]
mac, e = env.Get(a0.(Symbol))
if e != nil {
return nil, e
}
fn := mac.(PlumFunc)
ast, e = Apply(fn, slc[1:])
if e != nil {
return nil, e
}
}
return ast, nil
}
func eval_ast(ast PlumType, env EnvType) (PlumType, error) {
//fmt.Printf("eval_ast: %#v\n", ast)
if Symbol_Q(ast) {
return env.Get(ast.(Symbol))
} else if List_Q(ast) {
lst := []PlumType{}
for _, a := range ast.(List).Val {
exp, e := EVAL(a, env)
if e != nil {
return nil, e
}
lst = append(lst, exp)
}
return List{lst, nil}, nil
} else if Vector_Q(ast) {
lst := []PlumType{}
for _, a := range ast.(Vector).Val {
exp, e := EVAL(a, env)
if e != nil {
return nil, e
}
lst = append(lst, exp)
}
return Vector{lst, nil}, nil
} else if HashMap_Q(ast) {
m := ast.(HashMap)
new_hm := HashMap{map[string]PlumType{}, nil}
for k, v := range m.Val {
ke, e1 := EVAL(k, env)
if e1 != nil {
return nil, e1
}
if _, ok := ke.(string); !ok {
return nil, errors.New("non string hash-map key")
}
kv, e2 := EVAL(v, env)
if e2 != nil {
return nil, e2
}
new_hm.Val[ke.(string)] = kv
}
return new_hm, nil
} else {
return ast, nil
}
}
func EVAL(ast PlumType, env EnvType) (PlumType, error) {
var e error
for {
//fmt.Printf("EVAL: %v\n", printer.Pr_str(ast, true))
switch ast.(type) {
case List: // continue
default:
return eval_ast(ast, env)
}
// apply list
ast, e = macroexpand(ast, env)
if e != nil {
return nil, e
}
if !List_Q(ast) {
return ast, nil
}
a0 := ast.(List).Val[0]
var a1 PlumType = nil
var a2 PlumType = nil
switch len(ast.(List).Val) {
case 1:
a1 = nil
a2 = nil
case 2:
a1 = ast.(List).Val[1]
a2 = nil
default:
a1 = ast.(List).Val[1]
a2 = ast.(List).Val[2]
}
a0sym := "__<*fn*>__"
if Symbol_Q(a0) {
a0sym = a0.(Symbol).Val
}
switch a0sym {
case constants.DEFINE:
res, e := EVAL(a2, env)
if e != nil {
return nil, e
}
return env.Set(a1.(Symbol), res), nil
case constants.LET:
let_env, e := NewEnv(env, nil, nil)
if e != nil {
return nil, e
}
arr1, e := GetSlice(a1)
if e != nil {
return nil, e
}
for i := 0; i < len(arr1); i += 2 {
if !Symbol_Q(arr1[i]) {
return nil, errors.New("non-symbol bind value")
}
exp, e := EVAL(arr1[i+1], let_env)
if e != nil {
return nil, e
}
let_env.Set(arr1[i].(Symbol), exp)
}
ast = a2
env = let_env
case constants.QUOTE:
return a1, nil
case constants.QUASIQUOTE:
ast = quasiquote(a1)
case constants.DEFMACRO:
fn, e := EVAL(a2, env)
fn = fn.(PlumFunc).SetMacro()
if e != nil {
return nil, e
}
return env.Set(a1.(Symbol), fn), nil
case constants.MACROEXPAND:
return macroexpand(a1, env)
case constants.TRY:
var exc PlumType
exp, e := EVAL(a1, env)
if e == nil {
return exp, nil
} else {
if a2 != nil && List_Q(a2) {
a2s, _ := GetSlice(a2)
if Symbol_Q(a2s[0]) && (a2s[0].(Symbol).Val == "catch*") {
switch e.(type) {
case PlumError:
exc = e.(PlumError).Obj
default:
exc = e.Error()
}
binds := NewList(a2s[1])
new_env, e := NewEnv(env, binds, NewList(exc))
if e != nil {
return nil, e
}
exp, e = EVAL(a2s[2], new_env)
if e == nil {
return exp, nil
}
}
}
return nil, e
}
case constants.DO:
lst := ast.(List).Val
_, e := eval_ast(List{lst[1 : len(lst)-1], nil}, env)
if e != nil {
return nil, e
}
if len(lst) == 1 {
return nil, nil
}
ast = lst[len(lst)-1]
case constants.IF:
cond, e := EVAL(a1, env)
if e != nil {
return nil, e
}
if cond == nil || cond == false {
if len(ast.(List).Val) >= 4 {
ast = ast.(List).Val[3]
} else {
return nil, nil
}
} else {
ast = a2
}
case "fn*":
fn := PlumFunc{EVAL, a2, env, a1, false, NewEnv, nil}
return fn, nil
default:
el, e := eval_ast(ast, env)
if e != nil {
return nil, e
}
f := el.(List).Val[0]
if PlumFunc_Q(f) {
fn := f.(PlumFunc)
ast = fn.Exp
env, e = NewEnv(fn.Env, fn.Params, List{el.(List).Val[1:], nil})
if e != nil {
return nil, e
}
} else {
fn, ok := f.(Func)
if !ok {
return nil, errors.New("attempt to call non-function")
}
return fn.Fn(el.(List).Val[1:])
}
}
} // TCO loop
}
// print
func PRINT(exp PlumType) (string, error) {
return printer.Pr_str(exp, true), nil
}
var repl_env, _ = NewEnv(nil, nil, nil)
// repl
func repl(str string) (PlumType, error) {
var exp PlumType
var res string
var e error
if exp, e = READ(str); e != nil {
return nil, e
}
if exp, e = EVAL(exp, repl_env); e != nil {
return nil, e
}
if res, e = PRINT(exp); e != nil {
return nil, e
}
return res, nil
}
func main() {
// core.go: defined using go
for k, v := range core.NS {
repl_env.Set(Symbol{k}, Func{v.(func([]PlumType) (PlumType, error)), nil})
}
repl_env.Set(Symbol{"eval"}, Func{func(a []PlumType) (PlumType, error) {
return EVAL(a[0], repl_env)
}, nil})
repl_env.Set(Symbol{"*ARGV*"}, List{})
// core.Plum: defined using the language itself
repl("(define not (fn* (a) (if a false true)))")
repl("(define load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))")
repl("(defmacro cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))")
repl("(defmacro or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_FIXME ~(first xs)) (if or_FIXME or_FIXME (or ~@(rest xs))))))))")
repl("(define not1 (fn* (a) (if a false true)))")
repl(`(load-file "lib/base.p")`)
// called with Plum script to load and eval
if len(os.Args) > 1 {
args := make([]PlumType, 0, len(os.Args)-2)
for _, a := range os.Args[2:] {
args = append(args, a)
}
repl_env.Set(Symbol{"*ARGV*"}, List{args, nil})
if _, e := repl("(load-file \"" + os.Args[1] + "\")"); e != nil {
fmt.Printf("Error: %v\n", e)
os.Exit(1)
}
os.Exit(0)
}
// repl loop
for {
text, err := readline.Readline("user> ")
text = strings.TrimRight(text, "\n")
// fmt.Println(text)
if err != nil {
return
}
var out PlumType
var e error
if out, e = repl(text); e != nil {
if e.Error() == "<empty line>" {
continue
}
fmt.Printf("Error: %v\n", e)
continue
}
fmt.Printf("%v\n", out)
}
}