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janet/libs/bootstrap.gst

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# This file is executed without any macro expansion (macros are not
# yet defined). Cannot use macros or anything outside the stl.
# Helper for macro expansion
(def macroexpander (fn [x env f]
(if (= (type x) :tuple)
(if (> (length x) 0)
(do
(def first (get x 0))
(def macros (get env :macros))
(if macros
(do
(def macro (get macros first))
(if macro
(f (apply macro (slice x 1)))
x))
x)
x)
x)
x)))
# Macro expansion
(def macroexpand (fn [x env]
(macroexpander x (if env env (getenv)) macroexpander)))
# Function to create macros
(def global-macro (fn [name f]
(def env (getenv))
(def env-macros (get env :macros))
(def macros (if env-macros env-macros {}))
(set! env :macros macros)
(set! macros (symbol name) f)
f))
# Make defn
(global-macro "defn" (fn [name &]
(tuple 'def name (apply tuple 'fn &))))
# Make defmacro
(global-macro "defmacro" (fn [name &]
(tuple global-macro (string name) (apply tuple 'fn &))))
# Comment returns nil
(global-macro "comment" (fn [] nil))
# The source file to read from
(var *sourcefile* stdin)
# The *read* macro gets the next form from the source file, and
# returns it. It is a var and therefor can be overwritten.
(var *read* (fn []
(def b (buffer))
(def p (parser))
(while (not (parse-hasvalue p))
(read *sourcefile* 1 b)
(if (= (length b) 0)
(error "parse error: unexpected end of source"))
(parse-charseq p b)
(if (= (parse-status p) :error)
(error (string "parse error: " (parse-consume p))))
(clear b))
(parse-consume p)))
# Evaluates a form by macro-expanding it, compiling it, and
# then executing it.
(def eval (fn [x]
(def func (compile (macroexpand x)))
(if (= :function (type func))
(func)
(error (string "compiler error: " func)))))
# A simple repl for testing.
(while true
(def t (thread (fn []
(while true
(print (eval (*read*)))))))
(print (tran t)))