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03b6cfd45c
Neither keywords nor strings are modified by evaluation, so evaluating map keys is a no-op. Document this in the guide.
94 lines
2.4 KiB
Lua
Executable File
94 lines
2.4 KiB
Lua
Executable File
#!/usr/bin/env lua
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local table = require('table')
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local readline = require('readline')
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local utils = require('utils')
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local types = require('types')
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local reader = require('reader')
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local printer = require('printer')
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local Env = require('env')
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local List, Vector, HashMap = types.List, types.Vector, types.HashMap
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-- read
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function READ(str)
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return reader.read_str(str)
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end
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-- eval
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function eval_ast(ast, env)
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if types._symbol_Q(ast) then
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return env:get(ast)
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elseif types._list_Q(ast) then
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return List:new(utils.map(function(x) return EVAL(x,env) end,ast))
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elseif types._vector_Q(ast) then
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return Vector:new(utils.map(function(x) return EVAL(x,env) end,ast))
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elseif types._hash_map_Q(ast) then
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local new_hm = {}
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for k,v in pairs(ast) do
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new_hm[k] = EVAL(v, env)
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end
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return HashMap:new(new_hm)
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else
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return ast
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end
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end
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function EVAL(ast, env)
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--print("EVAL: "..printer._pr_str(ast,true))
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if not types._list_Q(ast) then return eval_ast(ast, env) end
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local a0,a1,a2 = ast[1], ast[2],ast[3]
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if not a0 then return ast end
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local a0sym = types._symbol_Q(a0) and a0.val or ""
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if 'def!' == a0sym then
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return env:set(a1, EVAL(a2, env))
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elseif 'let*' == a0sym then
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local let_env = Env:new(env)
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for i = 1,#a1,2 do
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let_env:set(a1[i], EVAL(a1[i+1], let_env))
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end
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return EVAL(a2, let_env)
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else
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local args = eval_ast(ast, env)
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local f = table.remove(args, 1)
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return f(table.unpack(args))
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end
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end
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-- print
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function PRINT(exp)
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return printer._pr_str(exp, true)
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end
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-- repl
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local repl_env = Env:new()
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function rep(str)
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return PRINT(EVAL(READ(str),repl_env))
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end
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repl_env:set(types.Symbol:new('+'), function(a,b) return a+b end)
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repl_env:set(types.Symbol:new('-'), function(a,b) return a-b end)
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repl_env:set(types.Symbol:new('*'), function(a,b) return a*b end)
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repl_env:set(types.Symbol:new('/'), function(a,b) return math.floor(a/b) end)
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if #arg > 0 and arg[1] == "--raw" then
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readline.raw = true
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end
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while true do
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line = readline.readline("user> ")
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if not line then break end
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xpcall(function()
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print(rep(line))
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end, function(exc)
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if exc then
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if types._malexception_Q(exc) then
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exc = printer._pr_str(exc.val, true)
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end
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print("Error: " .. exc)
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print(debug.traceback())
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end
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end)
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end
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