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1 | ;; Copyright (C) 2015 |
2 | ;; "Mu Lei" known as "NalaGinrut" <NalaGinrut@gmail.com> | |
3 | ;; This file is free software: you can redistribute it and/or modify | |
4 | ;; it under the terms of the GNU General Public License as published by | |
5 | ;; the Free Software Foundation, either version 3 of the License, or | |
6 | ;; (at your option) any later version. | |
7 | ||
8 | ;; This file is distributed in the hope that it will be useful, | |
9 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | ;; GNU General Public License for more details. | |
12 | ||
13 | ;; You should have received a copy of the GNU General Public License | |
14 | ;; along with this program. If not, see <http://www.gnu.org/licenses/>. | |
15 | ||
16 | (import (readline) (reader) (printer) (ice-9 match) (srfi srfi-43) | |
17 | (srfi srfi-1) (ice-9 receive) (env) (core) (types)) | |
18 | ||
19 | (define *toplevel* | |
20 | (receive (b e) (unzip2 core.ns) | |
dcd15199 | 21 | (make-Env #:binds b #:exprs (map make-func e)))) |
e658ffd2 | 22 | |
dd7a4f55 JM |
23 | (define (READ str) |
24 | (read_str str)) | |
e658ffd2 NG |
25 | |
26 | (define (eval_ast ast env) | |
27 | (define (_eval x) (EVAL x env)) | |
28 | (match ast | |
29 | ((? _nil? obj) obj) | |
30 | ((? symbol? sym) (env-has sym env)) | |
31 | ((? list? lst) (map _eval lst)) | |
32 | ((? vector? vec) (vector-map (lambda (i x) (_eval x)) vec)) | |
33 | ((? hash-table? ht) | |
dd7a4f55 JM |
34 | ;; NOTE: we must allocate a new hashmap here to avoid any side-effects, or |
35 | ;; there'll be strange bugs!!! | |
36 | (list->hash-map (hash-fold (lambda (k v p) (cons k (cons (_eval v) p))) '() ht))) | |
e658ffd2 NG |
37 | (else ast))) |
38 | ||
e658ffd2 NG |
39 | (define (eval_seq ast env) |
40 | (cond | |
41 | ((null? ast) nil) | |
42 | ((null? (cdr ast)) (EVAL (car ast) env)) | |
43 | (else | |
44 | (EVAL (car ast) env) | |
45 | (eval_seq (cdr ast) env)))) | |
46 | ||
47 | (define (is_macro_call ast env) | |
48 | (and (list? ast) | |
81eabb99 | 49 | (> (length ast) 0) |
85657c96 | 50 | (and=> (env-check (car ast) env) is-macro))) |
e658ffd2 NG |
51 | |
52 | (define (_macroexpand ast env) | |
53 | (cond | |
54 | ((is_macro_call ast env) | |
55 | => (lambda (c) | |
e658ffd2 NG |
56 | ;; NOTE: Macros are normal-order, so we shouldn't eval args here. |
57 | ;; Or it's applicable-order. | |
58 | (_macroexpand (callable-apply c (cdr ast)) env))) | |
59 | (else ast))) | |
60 | ||
61 | (define (EVAL ast env) | |
62 | (define (%unzip2 kvs) | |
63 | (let lp((next kvs) (k '()) (v '())) | |
64 | (cond | |
65 | ;; NOTE: reverse is very important here! | |
66 | ((null? next) (values (reverse k) (reverse v))) | |
dd7a4f55 JM |
67 | ((null? (cdr next)) |
68 | (throw 'mal-error (format #f "let*: Invalid binding form '~a'" kvs))) | |
e658ffd2 NG |
69 | (else (lp (cddr next) (cons (car next) k) (cons (cadr next) v)))))) |
70 | (define (_quasiquote obj) | |
71 | (match obj | |
72 | ((('unquote unq) rest ...) `(cons ,unq ,(_quasiquote rest))) | |
73 | (('unquote unq) unq) | |
74 | ((('splice-unquote unqsp) rest ...) `(concat ,unqsp ,(_quasiquote rest))) | |
75 | ((head rest ...) (list 'cons (_quasiquote head) (_quasiquote rest))) | |
76 | (else `(quote ,obj)))) | |
77 | ;; NOTE: I wish I can use (while #t ...) for that, but this is not Lispy, which means | |
78 | ;; it'll bring some trouble in control flow. We have to use continuations to return | |
79 | ;; and use non-standard `break' feature. In a word, not elegant at all. | |
80 | ;; The named let loop is natural for Scheme, but it looks a bit cheating. But NO! | |
81 | ;; Such kind of loop is actually `while loop' in Scheme, I don't take advantage of | |
82 | ;; TCO in Scheme to implement TCO, but it's the same principle with normal loop. | |
83 | ;; If you're Lispy enough, there's no recursive at all while you saw named let loop. | |
84 | (let tco-loop((ast ast) (env env)) ; expand as possible | |
e658ffd2 NG |
85 | (let ((ast (_macroexpand ast env))) |
86 | (match ast | |
87 | ((? non-list?) (eval_ast ast env)) | |
81eabb99 | 88 | (() ast) |
e658ffd2 NG |
89 | (('defmacro! k v) |
90 | (let ((c (EVAL v env))) | |
91 | (callable-is_macro-set! c #t) | |
92 | ((env 'set) k c))) | |
93 | (('macroexpand obj) (_macroexpand obj env)) | |
94 | (('quote obj) obj) | |
95 | (('quasiquote obj) (EVAL (_quasiquote (->list obj)) env)) | |
96 | (('def! k v) ((env 'set) k (EVAL v env))) | |
97 | (('let* kvs body) | |
98 | (let* ((new-env (make-Env #:outer env)) | |
99 | (setter (lambda (k v) ((new-env 'set) k (EVAL v new-env))))) | |
100 | (receive (keys vals) (%unzip2 (->list kvs)) | |
101 | (for-each setter keys vals)) | |
102 | (tco-loop body new-env))) | |
103 | (('do rest ...) | |
104 | (cond | |
dd7a4f55 JM |
105 | ((null? rest) |
106 | (throw 'mal-error (format #f "do: Invalid form! '~a'" rest))) | |
e658ffd2 NG |
107 | ((= 1 (length rest)) (tco-loop (car rest) env)) |
108 | (else | |
109 | (let ((mexpr (take rest (1- (length rest)))) | |
110 | (tail-call (car (take-right rest 1)))) | |
111 | (eval_seq mexpr env) | |
112 | (tco-loop tail-call env))))) | |
113 | (('if cnd thn els ...) | |
114 | (cond | |
115 | ((and (not (null? els)) (not (null? (cdr els)))) | |
116 | ;; Invalid `if' form | |
dd7a4f55 JM |
117 | (throw 'mal-error |
118 | (format #f "if: failed to match any pattern in form '~a'" ast))) | |
e658ffd2 NG |
119 | ((cond-true? (EVAL cnd env)) (tco-loop thn env)) |
120 | (else (if (null? els) nil (tco-loop (car els) env))))) | |
121 | (('fn* params body ...) ; function definition | |
dd7a4f55 | 122 | (make-anonymous-func |
e658ffd2 NG |
123 | (lambda args |
124 | (let ((nenv (make-Env #:outer env #:binds (->list params) #:exprs args))) | |
125 | (cond | |
dd7a4f55 JM |
126 | ((null? body) |
127 | (throw 'mal-error (format #f "fn*: bad lambda in form '~a'" ast))) | |
e658ffd2 NG |
128 | ((= 1 (length body)) (tco-loop (car body) nenv)) |
129 | (else | |
130 | (let ((mexpr (take body (1- (length body)))) | |
131 | (tail-call (car (take-right body 1)))) | |
132 | (eval_seq mexpr nenv) | |
133 | (tco-loop tail-call nenv)))))))) | |
dd7a4f55 JM |
134 | (else |
135 | (let ((el (map (lambda (x) (EVAL x env)) ast))) | |
136 | (callable-apply (car el) (cdr el)))))))) | |
e658ffd2 NG |
137 | |
138 | (define (EVAL-string str) | |
139 | (EVAL (read_str str) *toplevel*)) | |
140 | ||
141 | (define (PRINT exp) | |
142 | (and (not (eof-object? exp)) | |
e658ffd2 NG |
143 | (format #t "~a~%" (pr_str exp #t)))) |
144 | ||
145 | (define (LOOP continue?) | |
146 | (and continue? (REPL))) | |
147 | ||
148 | (define (REPL) | |
149 | (LOOP | |
dd7a4f55 JM |
150 | (let ((line (_readline "user> "))) |
151 | (cond | |
152 | ((eof-object? line) #f) | |
153 | ((string=? line "") #t) | |
154 | (else | |
155 | (catch 'mal-error | |
156 | (lambda () (PRINT (EVAL (READ line) *toplevel*))) | |
157 | (lambda (k . e) | |
158 | (format #t "Error: ~a~%" (pr_str (car e) #t))))))))) | |
e658ffd2 NG |
159 | |
160 | ;; initialization | |
161 | ((*toplevel* 'set) 'eval (make-func (lambda (ast) (EVAL ast *toplevel*)))) | |
162 | ((*toplevel* 'set) '*ARGV* '()) | |
17fc310d | 163 | (EVAL-string "(def! not (fn* (x) (if x false true)))") |
e658ffd2 NG |
164 | (EVAL-string "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))") |
165 | (EVAL-string "(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)))))))") | |
166 | (EVAL-string "(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))))))))") | |
1ad90e2b NG |
167 | |
168 | (let ((args (cdr (command-line)))) | |
2f60d14c NG |
169 | (cond |
170 | ((> (length args) 0) | |
4b3eaa74 NG |
171 | ((*toplevel* 'set) '*ARGV* (cdr args)) |
172 | (EVAL-string (string-append "(load-file \"" (car args) "\")"))) | |
173 | (else (REPL)))) |