julia/env.jl

   1 module env
   2
   3 export Env, env_set, env_find, env_get
   4
   5 type Env
   6     outer::Any
   7     data::Dict{Symbol,Any}
   8 end
   9
  10 function Env()
  11     Env(nothing, Dict())
  12 end
  13
  14 function Env(outer)
  15     Env(outer, Dict())
  16 end
  17
  18 function Env(outer, binds, exprs)
  19     e = Env(outer, Dict())
  20     for i=1:length(binds)
  21         if binds[i] == :&
  22             e.data[binds[i+1]] = exprs[i:end]
  23             break
  24         else
  25             e.data[binds[i]] = exprs[i]
  26         end
  27     end
  28     e
  29 end
  30
  31
  32 function env_set(env::Env, k::Symbol, v)
  33     env.data[k] = v
  34 end
  35
  36 function env_find(env::Env, k::Symbol)
  37     if haskey(env.data, k)
  38         env
  39     elseif env.outer != nothing
  40         env_find(env.outer, k)
  41     else
  42         nothing
  43     end
  44 end
  45
  46 function env_get(env::Env, k::Symbol)
  47     e = env_find(env, k)
  48     if e != nothing
  49         e.data[k]
  50     else
  51         error("'$(string(k))' not found")
  52     end
  53 end
  54
  55 end