vimscript/step4_if_fn_do.vim

   1 source readline.vim
   2 source types.vim
   3 source reader.vim
   4 source printer.vim
   5 source env.vim
   6 source core.vim
   7
   8 function READ(str)
   9   return ReadStr(a:str)
  10 endfunction
  11
  12 function EvalAst(ast, env)
  13   if SymbolQ(a:ast)
  14     let varname = a:ast.val
  15     return a:env.get(varname)
  16   elseif ListQ(a:ast)
  17     return ListNew(map(copy(a:ast.val), {_, e -> EVAL(e, a:env)}))
  18   elseif VectorQ(a:ast)
  19     return VectorNew(map(copy(a:ast.val), {_, e -> EVAL(e, a:env)}))
  20   elseif HashQ(a:ast)
  21     let ret = {}
  22     for [k,v] in items(a:ast.val)
  23       let keyobj = HashParseKey(k)
  24       let newkey = EVAL(keyobj, a:env)
  25       let newval = EVAL(v, a:env)
  26       let keystring = HashMakeKey(newkey)
  27       let ret[keystring] = newval
  28     endfor
  29     return HashNew(ret)
  30   else
  31     return a:ast
  32   end
  33 endfunction
  34
  35 function EVAL(ast, env)
  36   if !ListQ(a:ast)
  37     return EvalAst(a:ast, a:env)
  38   end
  39   if EmptyQ(a:ast)
  40     return a:ast
  41   endif
  42
  43   let first = ListFirst(a:ast)
  44   let first_symbol = SymbolQ(first) ? first.val : ""
  45   if first_symbol == "def!"
  46     let a1 = a:ast.val[1]
  47     let a2 = a:ast.val[2]
  48     let ret = a:env.set(a1.val, EVAL(a2, a:env))
  49     return ret
  50   elseif first_symbol == "let*"
  51     let a1 = a:ast.val[1]
  52     let a2 = a:ast.val[2]
  53     let let_env = NewEnv(a:env)
  54     let let_binds = a1.val
  55     let i = 0
  56     while i < len(let_binds)
  57       call let_env.set(let_binds[i].val, EVAL(let_binds[i+1], let_env))
  58       let i = i + 2
  59     endwhile
  60     return EVAL(a2, let_env)
  61   elseif first_symbol == "if"
  62     let condvalue = EVAL(a:ast.val[1], a:env)
  63     if FalseQ(condvalue) || NilQ(condvalue)
  64       if len(a:ast.val) < 4
  65         return g:MalNil
  66       else
  67         return EVAL(a:ast.val[3], a:env)
  68       endif
  69     else
  70       return EVAL(a:ast.val[2], a:env)
  71     endif
  72   elseif first_symbol == "do"
  73     let el = EvalAst(ListRest(a:ast), a:env)
  74     return el.val[-1]
  75   elseif first_symbol == "fn*"
  76     let fn = NewFn(ListNth(a:ast, 2), a:env, ListNth(a:ast, 1))
  77     return fn
  78   else
  79     " apply list
  80     let el = EvalAst(a:ast, a:env)
  81     let funcobj = ListFirst(el)
  82     let args = ListRest(el)
  83     if NativeFunctionQ(funcobj)
  84       return NativeFuncInvoke(funcobj, args)
  85     elseif FunctionQ(funcobj)
  86       return FuncInvoke(funcobj, args)
  87     else
  88       throw "Not a function"
  89     endif
  90   endif
  91 endfunction
  92
  93 function PRINT(exp)
  94   return PrStr(a:exp, 1)
  95 endfunction
  96
  97 function REP(str, env)
  98   return PRINT(EVAL(READ(a:str), a:env))
  99 endfunction
 100
 101 let repl_env = NewEnv("")
 102
 103 for [k, Fn] in items(CoreNs)
 104   call repl_env.set(k, Fn)
 105 endfor
 106
 107 call REP("(def! not (fn* (a) (if a false true)))", repl_env)
 108
 109 while 1
 110   let [eof, line] = Readline("user> ")
 111   if eof
 112     break
 113   endif
 114   if line == ""
 115     continue
 116   endif
 117   try
 118     call PrintLn(REP(line, repl_env))
 119   catch
 120     call PrintLn("Error: " . v:exception)
 121   endtry
 122 endwhile
 123 qall!