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130 lines
3.2 KiB
130 lines
3.2 KiB
#! /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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require "./core"
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require "./error"
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# Note:
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# Employed downcase names because Crystal prohibits uppercase names for methods
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def func_of(env, binds, body)
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-> (args : Array(Mal::Type)) {
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new_env = Mal::Env.new(env, binds, args)
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eval(body, new_env)
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} as Mal::Func
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end
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def eval_ast(ast, env)
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return ast.map{|n| eval(n, env) as Mal::Type} if ast.is_a? Mal::List
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val = ast.unwrap
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Mal::Type.new case val
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when Mal::Symbol
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if e = env.get(val.str)
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e
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else
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eval_error "'#{val.str}' not found"
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end
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when Mal::List
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val.each_with_object(Mal::List.new){|n, l| l << eval(n, env)}
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when Mal::Vector
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val.each_with_object(Mal::Vector.new){|n, l| l << eval(n, env)}
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when Mal::HashMap
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val.each{|k, v| val[k] = eval(v, env)}
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val
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else
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val
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end
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end
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def eval_invocation(list, env)
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f = eval(list.first, env).unwrap
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eval_error "expected function symbol as the first symbol of list" unless f.is_a? Mal::Func
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f.call eval_ast(list[1..-1].each_with_object(Mal::List.new){|i, l| l << i}, env)
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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(ast, env)
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list = ast.unwrap
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return eval_ast(ast, env) unless list.is_a? Mal::List
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return gen_type Mal::List if list.empty?
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head = list.first.unwrap
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Mal::Type.new case head
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when Mal::Symbol
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case head.str
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when "def!"
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eval_error "wrong number of argument for 'def!'" unless list.size == 3
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a1 = list[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(list[2], env))
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when "let*"
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eval_error "wrong number of argument for 'def!'" unless list.size == 3
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bindings = list[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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key, value = binding
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name = key.unwrap
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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(list[2], new_env)
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when "do"
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list.shift 1
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eval_ast(list, env).last
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when "if"
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cond = eval(list[1], env).unwrap
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case cond
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when Nil
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list.size >= 4 ? eval(list[3], env) : nil
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when false
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list.size >= 4 ? eval(list[3], env) : nil
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else
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eval(list[2], env)
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end
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when "fn*"
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# Note:
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# If writing lambda expression here directly, compiler will fail to infer type of 'list'. (Error 'Nil for empty?')
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func_of(env, list[1].unwrap, list[2])
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else
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eval_invocation(list, env)
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end
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else
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eval_invocation(list, env)
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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), $repl_env))
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end
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$repl_env = Mal::Env.new nil
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Mal::NS.each{|k,v| $repl_env.set(k, Mal::Type.new(v))}
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rep "(def! not (fn* (a) (if a false true)))"
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while line = my_readline("user> ")
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begin
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puts 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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