|
|
- #! /usr/bin/env crystal run
-
- require "./readline"
- require "./reader"
- require "./printer"
- require "./types"
- require "./env"
- require "./core"
- require "./error"
-
- # Note:
- # Employed downcase names because Crystal prohibits uppercase names for methods
-
- def func_of(env, binds, body)
- -> (args : Array(Mal::Type)) {
- new_env = Mal::Env.new(env, binds, args)
- eval(body, new_env)
- } as Mal::Func
- end
-
- def eval_ast(ast, env)
- return ast.map{|n| eval(n, env) as Mal::Type} if ast.is_a? Mal::List
-
- val = ast.unwrap
-
- Mal::Type.new case val
- when Mal::Symbol
- if e = env.get(val.str)
- e
- else
- eval_error "'#{val.str}' not found"
- end
- when Mal::List
- val.each_with_object(Mal::List.new){|n, l| l << eval(n, env)}
- when Mal::Vector
- val.each_with_object(Mal::Vector.new){|n, l| l << eval(n, env)}
- when Array(Mal::Type)
- val.map{|n| eval(n, env)}
- when Mal::HashMap
- val.each{|k, v| val[k] = eval(v, env)}
- val
- else
- val
- end
- end
-
- def read(str)
- read_str str
- end
-
- macro pair?(list)
- {{list}}.is_a?(Array) && !{{list}}.empty?
- end
-
- def quasiquote(ast)
- list = ast.unwrap
-
- unless pair?(list)
- return Mal::Type.new(
- Mal::List.new << gen_type(Mal::Symbol, "quote") << ast
- )
- end
-
- head = list.first.unwrap
-
- case
- # ("unquote" ...)
- when head.is_a?(Mal::Symbol) && head.str == "unquote"
- list[1]
- # (("splice-unquote" ...) ...)
- when pair?(head) && (arg0 = head.first.unwrap).is_a?(Mal::Symbol) && arg0.str == "splice-unquote"
- tail = Mal::Type.new list[1..-1].to_mal
- Mal::Type.new(
- Mal::List.new << gen_type(Mal::Symbol, "concat") << head[1] << quasiquote(tail)
- )
- else
- tail = Mal::Type.new list[1..-1].to_mal
- Mal::Type.new(
- Mal::List.new << gen_type(Mal::Symbol, "cons") << quasiquote(list.first) << quasiquote(tail)
- )
- end
- end
-
- def macro_call?(ast, env)
- list = ast.unwrap
- return false unless list.is_a? Mal::List
-
- sym = list.first.unwrap
- return false unless sym.is_a? Mal::Symbol
-
- func = env.find(sym.str).try(&.data[sym.str])
- return false unless func && func.macro?
-
- true
- end
-
- def macroexpand(ast, env)
- while macro_call?(ast, env)
-
- # Already checked in macro_call?
- list = ast.unwrap as Mal::List
- func_sym = list[0].unwrap as Mal::Symbol
- func = env.get(func_sym.str).unwrap
-
- case func
- when Mal::Func
- ast = func.call(list[1..-1])
- when Mal::Closure
- ast = func.fn.call(list[1..-1])
- else
- eval_error "macro '#{func_sym.str}' must be function: #{ast}"
- end
- end
-
- ast
- end
-
- macro invoke_list(l, env)
- f = eval({{l}}.first, {{env}}).unwrap
- args = eval_ast({{l}}[1..-1].to_mal, {{env}})
- case f
- when Mal::Closure
- ast = f.ast
- {{env}} = Mal::Env.new(f.env, f.params, args)
- next # TCO
- when Mal::Func
- return f.call args
- else
- eval_error "expected function as the first argument: #{f}"
- end
- end
-
- def eval(ast, env)
- # 'next' in 'do...end' has a bug in crystal 0.7.1
- # https://github.com/manastech/crystal/issues/659
- while true
- return eval_ast(ast, env) unless ast.unwrap.is_a? Mal::List
-
- ast = macroexpand(ast, env)
-
- list = ast.unwrap
-
- return ast unless list.is_a? Mal::List
- return ast if list.empty?
-
- head = list.first.unwrap
-
- return invoke_list(list, env) unless head.is_a? Mal::Symbol
-
- return Mal::Type.new case head.str
- when "def!"
- eval_error "wrong number of argument for 'def!'" unless list.size == 3
- a1 = list[1].unwrap
- eval_error "1st argument of 'def!' must be symbol: #{a1}" unless a1.is_a? Mal::Symbol
- env.set(a1.str, eval(list[2], env))
- when "let*"
- eval_error "wrong number of argument for 'def!'" unless list.size == 3
-
- bindings = list[1].unwrap
- eval_error "1st argument of 'let*' must be list or vector" unless bindings.is_a? Array
- eval_error "size of binding list must be even" unless bindings.size.even?
-
- new_env = Mal::Env.new env
- bindings.each_slice(2) do |binding|
- key, value = binding
- name = key.unwrap
- eval_error "name of binding must be specified as symbol #{name}" unless name.is_a? Mal::Symbol
- new_env.set(name.str, eval(value, new_env))
- end
-
- ast, env = list[2], new_env
- next # TCO
- when "do"
- if list.empty?
- ast = Mal::Type.new nil
- next
- end
-
- eval_ast(list[1..-2].to_mal, env)
- ast = list.last
- next # TCO
- when "if"
- ast = unless eval(list[1], env).unwrap
- list.size >= 4 ? list[3] : Mal::Type.new(nil)
- else
- list[2]
- end
- next # TCO
- when "fn*"
- params = list[1].unwrap
- unless params.is_a? Array
- eval_error "'fn*' parameters must be list or vector: #{params}"
- end
- Mal::Closure.new(list[2], params, env, func_of(env, params, list[2]))
- when "quote"
- list[1]
- when "quasiquote"
- ast = quasiquote list[1]
- next # TCO
- when "defmacro!"
- eval_error "wrong number of argument for 'defmacro!'" unless list.size == 3
- a1 = list[1].unwrap
- eval_error "1st argument of 'defmacro!' must be symbol: #{a1}" unless a1.is_a? Mal::Symbol
- env.set(a1.str, eval(list[2], env).tap{|n| n.is_macro = true})
- when "macroexpand"
- macroexpand(list[1], env)
- when "try*"
- catch_list = list[2].unwrap
- return eval(list[1], env) unless catch_list.is_a? Mal::List
-
- catch_head = catch_list.first.unwrap
- return eval(list[1], env) unless catch_head.is_a? Mal::Symbol
- return eval(list[1], env) unless catch_head.str == "catch*"
-
- begin
- eval(list[1], env)
- rescue e : Mal::RuntimeException
- new_env = Mal::Env.new(env, [catch_list[1]], [e.thrown])
- eval(catch_list[2], new_env)
- rescue e
- new_env = Mal::Env.new(env, [catch_list[1]], [Mal::Type.new e.message])
- eval(catch_list[2], new_env)
- end
- else
- invoke_list(list, env)
- end
- end
- end
-
- def print(result)
- pr_str(result, true)
- end
-
- def rep(str)
- print(eval(read(str), $repl_env))
- end
-
- $repl_env = Mal::Env.new nil
- Mal::NS.each{|k,v| $repl_env.set(k, Mal::Type.new(v))}
- $repl_env.set("eval", Mal::Type.new -> (args: Array(Mal::Type)){ eval(args[0], $repl_env) })
- rep "(def! not (fn* (a) (if a false true)))"
- rep "(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))"
- rep "(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)))))))"
- rep "(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))))))))"
-
- $argv = Mal::List.new
- $repl_env.set("*ARGV*", Mal::Type.new $argv)
-
- unless ARGV.empty?
- if ARGV.size > 1
- ARGV[1..-1].each do |a|
- $argv << Mal::Type.new(a)
- end
- end
-
- begin
- rep "(load-file \"#{ARGV[0]}\")"
- rescue e
- STDERR.puts e
- end
- exit
- end
-
- while line = my_readline("user> ")
- begin
- puts rep(line)
- rescue e
- STDERR.puts e
- end
- end
|