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7f0ce0f0 VS |
1 | (import (scheme base)) |
2 | (import (scheme write)) | |
3 | (import (scheme process-context)) | |
4 | ||
5 | (import (lib util)) | |
6 | (import (lib reader)) | |
7 | (import (lib printer)) | |
8 | (import (lib types)) | |
9 | (import (lib env)) | |
10 | (import (lib core)) | |
11 | ||
12 | (define (READ input) | |
13 | (read-str input)) | |
14 | ||
15 | (define (eval-ast ast env) | |
16 | (let ((type (and (mal-object? ast) (mal-type ast))) | |
17 | (value (and (mal-object? ast) (mal-value ast)))) | |
18 | (case type | |
19 | ((symbol) (env-get env value)) | |
20 | ((list) (mal-list (map (lambda (item) (EVAL item env)) value))) | |
21 | ((vector) (mal-vector (vector-map (lambda (item) (EVAL item env)) value))) | |
22 | ((map) (mal-map (alist-map (lambda (key value) (cons key (EVAL value env))) value))) | |
23 | (else ast)))) | |
24 | ||
25 | (define (is-pair? ast) | |
26 | (let ((type (and (mal-object? ast) (mal-type ast)))) | |
27 | (if (memq type '(list vector)) | |
28 | (pair? (->list (mal-value ast))) | |
29 | #f))) | |
30 | ||
31 | (define (QUASIQUOTE ast) | |
32 | (if (not (is-pair? ast)) | |
33 | (mal-list (list (mal-symbol 'quote) ast)) | |
34 | (let* ((items (->list (mal-value ast))) | |
35 | (a0 (car items))) | |
36 | (if (and (mal-object? a0) | |
37 | (eq? (mal-type a0) 'symbol) | |
38 | (eq? (mal-value a0) 'unquote)) | |
39 | (cadr items) | |
40 | (if (and (is-pair? a0) | |
41 | (mal-object? (car (mal-value a0))) | |
42 | (eq? (mal-type (car (mal-value a0))) 'symbol) | |
43 | (eq? (mal-value (car (mal-value a0))) 'splice-unquote)) | |
44 | (mal-list (list (mal-symbol 'concat) | |
45 | (cadr (mal-value a0)) | |
46 | (QUASIQUOTE (mal-list (cdr items))))) | |
47 | (mal-list (list (mal-symbol 'cons) | |
48 | (QUASIQUOTE a0) | |
49 | (QUASIQUOTE (mal-list (cdr items)))))))))) | |
50 | ||
51 | (define (EVAL ast env) | |
52 | (let ((type (and (mal-object? ast) (mal-type ast)))) | |
53 | (if (not (eq? type 'list)) | |
54 | (eval-ast ast env) | |
55 | (let ((items (mal-value ast))) | |
56 | (if (null? items) | |
57 | ast | |
58 | (let ((a0 (car items))) | |
59 | (case (and (mal-object? a0) (mal-value a0)) | |
60 | ((def!) | |
61 | (let ((symbol (mal-value (cadr items))) | |
62 | (value (EVAL (list-ref items 2) env))) | |
63 | (env-set env symbol value) | |
64 | value)) | |
65 | ((let*) | |
66 | (let ((env* (make-env env)) | |
67 | (binds (->list (mal-value (cadr items)))) | |
68 | (form (list-ref items 2))) | |
69 | (let loop ((binds binds)) | |
70 | (when (pair? binds) | |
71 | (let ((key (mal-value (car binds)))) | |
72 | (when (null? (cdr binds)) | |
73 | (error "unbalanced list")) | |
74 | (let ((value (EVAL (cadr binds) env*))) | |
75 | (env-set env* key value) | |
76 | (loop (cddr binds)))))) | |
77 | (EVAL form env*))) ; TCO | |
78 | ((do) | |
79 | (let ((forms (cdr items))) | |
80 | (if (null? forms) | |
81 | mal-nil | |
82 | ;; the evaluation order of map is unspecified | |
83 | (let loop ((forms forms)) | |
84 | (let ((form (car forms)) | |
85 | (tail (cdr forms))) | |
86 | (if (null? tail) | |
87 | (EVAL form env) ; TCO | |
88 | (begin | |
89 | (EVAL form env) | |
90 | (loop tail)))))))) | |
91 | ((if) | |
92 | (let* ((condition (EVAL (cadr items) env)) | |
93 | (type (and (mal-object? condition) | |
94 | (mal-type condition)))) | |
95 | (if (memq type '(false nil)) | |
96 | (if (< (length items) 4) | |
97 | mal-nil | |
98 | (EVAL (list-ref items 3) env)) ; TCO | |
99 | (EVAL (list-ref items 2) env)))) ; TCO | |
100 | ((quote) (cadr items)) | |
101 | ((quasiquote) (EVAL (QUASIQUOTE (cadr items)) env)) ; TCO | |
102 | ((fn*) | |
103 | (let* ((binds (->list (mal-value (cadr items)))) | |
104 | (binds (map mal-value binds)) | |
105 | (body (list-ref items 2)) | |
106 | (fn (lambda args | |
107 | (let ((env* (make-env env binds args))) | |
108 | (EVAL body env*))))) | |
109 | (make-func body binds env fn))) | |
110 | (else | |
111 | (let* ((items (mal-value (eval-ast ast env))) | |
112 | (op (car items)) | |
113 | (ops (cdr items))) | |
114 | (if (func? op) | |
115 | (let* ((outer (func-env op)) | |
116 | (binds (func-params op)) | |
117 | (env* (make-env outer binds ops))) | |
118 | (EVAL (func-ast op) env*)) ; TCO | |
119 | (apply op ops))))))))))) | |
120 | ||
121 | (define (PRINT ast) | |
122 | (pr-str ast #t)) | |
123 | ||
124 | (define repl-env (make-env #f)) | |
125 | (for-each (lambda (kv) (env-set repl-env (car kv) (cdr kv))) ns) | |
126 | ||
127 | (define (rep input) | |
128 | (PRINT (EVAL (READ input) repl-env))) | |
129 | ||
130 | (define argv (cdr (command-line))) | |
131 | ||
132 | (env-set repl-env 'eval (lambda (ast) (EVAL ast repl-env))) | |
133 | (env-set repl-env '*ARGV* (mal-list (map mal-string (cdr-safe argv)))) | |
134 | ||
135 | (rep "(def! not (fn* (a) (if a false true)))") | |
136 | (rep "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))") | |
137 | ||
138 | (define (readline prompt) | |
139 | (display prompt) | |
140 | (flush-output-port) | |
141 | (let ((input (read-line))) | |
142 | (if (eof-object? input) | |
143 | #f | |
144 | input))) | |
145 | ||
146 | (define (main) | |
147 | (let loop () | |
148 | (let ((input (readline "user> "))) | |
149 | (when input | |
150 | (guard | |
151 | (ex ((error-object? ex) | |
152 | (when (not (memv 'empty-input (error-object-irritants ex))) | |
153 | (display "[error] ") | |
154 | (display (error-object-message ex)) | |
155 | (newline)))) | |
156 | (display (rep input)) | |
157 | (newline)) | |
158 | (loop)))) | |
159 | (newline)) | |
160 | ||
161 | (if (null? argv) | |
162 | (main) | |
163 | (rep (string-append "(load-file \"" (car argv) "\")"))) |