mirror of
https://github.com/kanaka/mal.git
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8a19f60386
- Reorder README to have implementation list after "learning tool" bullet. - This also moves tests/ and libs/ into impls. It would be preferrable to have these directories at the top level. However, this causes difficulties with the wasm implementations which need pre-open directories and have trouble with paths starting with "../../". So in lieu of that, symlink those directories to the top-level. - Move the run_argv_test.sh script into the tests directory for general hygiene.
121 lines
3.2 KiB
Crystal
Executable File
121 lines
3.2 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?(Int64) && y.is_a?(Int64)
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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 : Int64, y : Int64) { x + y }))
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REPL_ENV.set("-", Mal::Type.new num_func(->(x : Int64, y : Int64) { x - y }))
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REPL_ENV.set("*", Mal::Type.new num_func(->(x : Int64, y : Int64) { x * y }))
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REPL_ENV.set("/", Mal::Type.new num_func(->(x : Int64, y : Int64) { 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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return gen_type Mal::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 = Readline.readline("user> ", true)
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begin
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puts Mal.rep(line)
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rescue e : Mal::RuntimeException
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STDERR.puts "Error: #{pr_str(e.thrown, true)}"
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rescue e
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STDERR.puts "Error: #{e}"
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end
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end
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