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https://github.com/kanaka/mal.git
synced 2024-11-10 02:45:44 +03:00
120 lines
3.1 KiB
Crystal
Executable File
120 lines
3.1 KiB
Crystal
Executable File
#! /usr/bin/env crystal run
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require "./readline"
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require "./reader"
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require "./printer"
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require "./types"
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require "./env"
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# Note:
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# Employed downcase names because Crystal prohibits uppercase names for methods
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def eval_error(msg)
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raise Mal::EvalException.new msg
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end
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def num_func(func)
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-> (args : Array(Mal::Type)) {
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x, y = args[0].unwrap, args[1].unwrap
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eval_error "invalid arguments" unless x.is_a?(Int32) && y.is_a?(Int32)
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Mal::Type.new func.call(x, y)
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}
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end
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$repl_env = Mal::Env.new nil
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$repl_env.set("+", Mal::Type.new num_func(->(x : Int32, y : Int32){ x + y }))
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$repl_env.set("-", Mal::Type.new num_func(->(x : Int32, y : Int32){ x - y }))
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$repl_env.set("*", Mal::Type.new num_func(->(x : Int32, y : Int32){ x * y }))
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$repl_env.set("/", Mal::Type.new num_func(->(x : Int32, y : Int32){ x / y }))
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module Mal
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extend self
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def eval_ast(a, env)
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return a.map{|n| eval(n, env) } if a.is_a? Array
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Mal::Type.new case ast = a.unwrap
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when Mal::Symbol
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if e = env.get(ast.str)
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e
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else
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eval_error "'#{ast.str}' not found"
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end
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when Mal::List
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ast.each_with_object(Mal::List.new){|n, l| l << eval(n, env)}
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when Mal::Vector
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ast.each_with_object(Mal::Vector.new){|n, l| l << eval(n, env)}
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when Mal::HashMap
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new_map = Mal::HashMap.new
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ast.each{|k, v| new_map[k] = eval(v, env)}
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new_map
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else
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ast
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end
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end
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def read(str)
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read_str str
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end
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def eval(t, env)
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ast = t.unwrap
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return eval_ast(t, env) unless ast.is_a?(Mal::List)
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eval_error "empty list" if ast.empty?
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sym = ast.first.unwrap
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eval_error "first element of list must be a symbol" unless sym.is_a?(Mal::Symbol)
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Mal::Type.new case sym.str
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when "def!"
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eval_error "wrong number of argument for 'def!'" unless ast.size == 3
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a1 = ast[1].unwrap
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eval_error "1st argument of 'def!' must be symbol" unless a1.is_a?(Mal::Symbol)
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env.set(a1.str, eval(ast[2], env) as Mal::Type)
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when "let*"
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eval_error "wrong number of argument for 'def!'" unless ast.size == 3
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bindings = ast[1].unwrap
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eval_error "1st argument of 'let*' must be list or vector" unless bindings.is_a?(Array)
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eval_error "size of binding list must be even" unless bindings.size.even?
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new_env = Mal::Env.new env
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bindings.each_slice(2) do |binding|
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name, value = binding[0].unwrap, binding[1]
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eval_error "name of binding must be specified as symbol" unless name.is_a?(Mal::Symbol)
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new_env.set(name.str, eval(value, new_env))
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end
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eval(ast[2], new_env)
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else
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f = eval_ast(ast.first, env)
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ast.shift(1)
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args = eval_ast(ast, env)
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if f.is_a?(Mal::Type) && (f2 = f.unwrap).is_a?(Mal::Func)
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f2.call(args as Array(Mal::Type))
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else
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eval_error "expected function symbol as the first symbol of list"
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end
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end
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end
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def print(result)
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pr_str(result, true)
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end
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def rep(str)
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print(eval(read(str), $repl_env))
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end
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end
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while line = my_readline("user> ")
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begin
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puts Mal.rep(line)
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rescue e
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STDERR.puts e
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end
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end
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