X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=forth.jl.git;a=blobdiff_plain;f=src%2Fforth.jl;h=2bd68b9ab1475d5901645ba1fe67bedae223a1d0;hp=4b625bc146eb19cbcc36a51f6ab414789726645d;hb=40ee2b7687b038db08a7337fc1ca36cc70633167;hpb=03de266dbc3975cfa2f3b07de2d58ff642f4bf76

diff --git a/src/forth.jl b/src/forth.jl
index 4b625bc..2bd68b9 100644
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,53 +1,35 @@
 module forth
 
+import Base.REPLCompletions
+
 # VM mem size
-size_mem = 640*1024
+size_mem = 1000000 # 1 mega-int
 
 # Buffer sizes
-size_RS = 1024   # Return stack size
-size_PS = 1024   # Parameter stack size
-size_TIB = 1096  # Terminal input buffer size
-
-# The mem array constitutes the memory of the VM. It has the following geography:
-#
-# mem = +-----------------------+
-#       | Built-in Variables    |
-#       +-----------------------+
-#       | Return Stack          |
-#       +-----------------------+
-#       | Parameter Stack       |
-#       +-----------------------+
-#       | Terminal Input Buffer |
-#       +-----------------------+
-#       | Dictionary            |
-#       +-----------------------+
-#
-# Note that all words (user-defined, primitive, variables, etc) are included in
-# the dictionary.
-#
-# Simple linear addressing is used with one exception: references to primitive code
-# blocks, which are represented as anonymous functions, appear the negative index
-# into the primitives array which contains only these functions.
+size_RS = 1000   # Return stack size
+size_PS = 1000   # Parameter stack size
+size_TIB = 1000  # Terminal input buffer size
 
+# Memory arrays
 mem = Array{Int64,1}(size_mem)
 primitives = Array{Function,1}()
-primNames = Array{ASCIIString,1}()
+primNames = Array{AbstractString,1}()
 
-# Built-in variables
+# Memory geography and built-in variables
 
 nextVarAddr = 1
-RSP0 = nextVarAddr; nextVarAddr += 1
-PSP0 = nextVarAddr; nextVarAddr += 1
-HERE = nextVarAddr; nextVarAddr += 1
-LATEST = nextVarAddr; nextVarAddr += 1
+H = nextVarAddr; nextVarAddr += 1              # Next free memory address
+FORTH_LATEST = nextVarAddr; nextVarAddr += 1   # FORTH dict latest
+CURRENT = nextVarAddr; nextVarAddr += 1        # Current compilation dict
 
-mem[RSP0] = nextVarAddr              # bottom of RS
-mem[PSP0] = mem[RSP0] + size_RS      # bottom of PS
-TIB = mem[PSP0] + size_PS            # address of terminal input buffer
-mem[HERE] = TIB + size_TIB           # location of bottom of dictionary
-mem[LATEST] = 0                      # no previous definition
+RSP0 = nextVarAddr                  # bottom of RS
+PSP0 = RSP0 + size_RS               # bottom of PS
+TIB = PSP0 + size_PS                # address of terminal input buffer
+mem[H] = TIB + size_TIB             # location of bottom of dictionary
+mem[FORTH_LATEST] = 0               # zero FORTH dict latest (no previous def)
+mem[CURRENT] = FORTH_LATEST-1       # Compile words to system dict initially
 
-DICT = mem[HERE] # Save bottom of dictionary as constant
+DICT = mem[H] # Save bottom of dictionary as constant
 
 # VM registers
 type Reg
@@ -55,30 +37,37 @@ type Reg
     PSP::Int64  # Parameter/data stack pointer
     IP::Int64   # Instruction pointer
     W::Int64    # Working register
-    X::Int64    # Extra register
 end
-reg = Reg(mem[RSP0], mem[PSP0], 0, 0, 0)
-
-# Stack manipulation
-
-type StackUnderflow <: Exception end
+reg = Reg(RSP0, PSP0, 0, 0)
 
-getRSDepth() = reg.RSP - mem[RSP0]
-getPSDepth() = reg.PSP - mem[PSP0]
+# Stack manipulation functions
 
 function ensurePSDepth(depth::Int64)
-    if getPSDepth()<depth
-        throw(StackUnderflow())
+    if reg.PSP - PSP0 < depth
+        error("Parameter stack underflow.")
+    end
+end
+
+function ensurePSCapacity(toAdd::Int64)
+    if reg.PSP + toAdd >= PSP0 + size_PS
+        error("Parameter stack overflow.")
     end
 end
 
 function ensureRSDepth(depth::Int64)
-    if getRSDepth()<depth
-        throw(StackUnderflow())
+    if reg.RSP - RSP0 < depth
+        error("Return stack underflow.")
+    end
+end
+
+function ensureRSCapacity(toAdd::Int64)
+    if reg.RSP + toAdd >= RSP0 + size_RS
+        error("Return stack overflow.")
     end
 end
 
 function pushRS(val::Int64)
+    ensureRSCapacity(1)
     mem[reg.RSP+=1] = val
 end
 
@@ -91,6 +80,8 @@ function popRS()
 end
 
 function pushPS(val::Int64)
+    ensurePSCapacity(1)
+
     mem[reg.PSP += 1] = val
 end
 
@@ -104,789 +95,1139 @@ end
 
 # Handy functions for adding/retrieving strings to/from memory.
 
-getString(addr::Int64, len::Int64) = ASCIIString([Char(c) for c in mem[addr:(addr+len-1)]])
-function putString(str::ASCIIString, addr::Int64)
-    mem[addr:(addr+length(str)-1)] = [Int64(c) for c in str]
+getString(addr::Int64, len::Int64) = AbstractString([Char(c) for c in mem[addr:(addr+len-1)]])
+
+function putString(str::AbstractString, addr::Int64, maxLen::Int64)
+    len = min(length(str), maxLen)
+    mem[addr:(addr+len-1)] = [Int64(c) for c in str]
 end
 
+stringAsInts(str::AbstractString) = [Int(c) for c in collect(str)]
+
 # Primitive creation and calling functions
 
+function defPrim(f::Function; name="nameless")
+    push!(primitives, f)
+    push!(primNames, replace(name, "\004", "EOF"))
+
+    return -length(primitives)
+end
+
+function callPrim(addr::Int64)
+    if addr >=0 || -addr>length(primitives)
+        error("Attempted to execute non-existent primitive at address $addr.")
+    else
+        primitives[-addr]()
+    end
+end
+getPrimName(addr::Int64) = primNames[-addr]
+
+# Word creation functions
+
+F_LENMASK = 31
+F_IMMED = 32
+F_HIDDEN = 64
+NFA_MARK = 128
+
+function dictWrite(ints::Array{Int64,1})
+    mem[mem[H]:(mem[H]+length(ints)-1)] = ints
+    mem[H] += length(ints)
+end
+dictWrite(int::Int64) = dictWrite([int])
+dictWriteString(string::AbstractString) = dictWrite([Int64(c) for c in string])
+
 function createHeader(name::AbstractString, flags::Int64)
-    mem[mem[HERE]] = mem[LATEST]
-    mem[LATEST] = mem[HERE]
-    mem[HERE] += 1
+    mem[mem[H]] = mem[mem[CURRENT]+1]
+    mem[mem[CURRENT]+1] = mem[H]
+    mem[H] += 1
 
-    mem[mem[HERE]] = length(name) | flags; mem[HERE] += 1
-    putString(name, mem[HERE]); mem[HERE] += length(name)
+    dictWrite(length(name) | flags | NFA_MARK)
+    dictWriteString(name)
 end
 
-function defPrim(name::AbstractString, f::Function; flags::Int64=0)
+function defPrimWord(name::AbstractString, f::Function; flags::Int64=0)
     createHeader(name, flags)
 
-    codeWordAddr = mem[HERE]
-    push!(primitives, f)
-    mem[codeWordAddr] = -length(primitives)
-    mem[HERE] += 1
-
-    push!(primNames, name)
+    codeWordAddr = mem[H]
+    dictWrite(defPrim(f, name=name))
 
     return codeWordAddr
 end
 
-callPrim(addr::Int64) = primitives[-addr]()
+function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
+    createHeader(name, flags)
+
+    addr = mem[H]
+    dictWrite(DOCOL)
+
+    dictWrite(wordAddrs)
+
+    return addr
+end
+
+# Variable creation functions
 
 function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
-    defPrim(name, eval(:(() -> begin
+
+    defPrimWord(name, eval(:(() -> begin
         pushPS($(varAddr))
-        return mem[NEXT]
+        return NEXT
     end)))
 end
 
-function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
+function defNewVar(name::AbstractString, initial::Array{Int64,1}; flags::Int64=0)
     createHeader(name, flags)
     
-    codeWordAddr = mem[HERE]
-    varAddr = mem[HERE] + 1
-    push!(primitives, eval(:(() -> begin
-        pushPS($(varAddr))
-        return mem[NEXT]
-    end)))
-    mem[mem[HERE]] = -length(primitives); mem[HERE] += 1
+    codeWordAddr = mem[H]
+    varAddr = mem[H] + 1
 
-    mem[mem[HERE]] = initial; mem[HERE] += 1
+    dictWrite(DOVAR)
+    dictWrite(initial)
 
     return varAddr, codeWordAddr
 end
 
-function defConst(name::AbstractString, val::Int64; flags::Int64=0)
-    defPrim(name, eval(:(() -> begin
-        pushPS($(val))
-        return mem[NEXT]
-    end)))
+defNewVar(name::AbstractString, initial::Int64; flags::Int64=0) =
+    defNewVar(name, [initial]; flags=flags)
 
-    return val
-end
-
-function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
+function defConst(name::AbstractString, val::Int64; flags::Int64=0)
     createHeader(name, flags)
 
-    addr = mem[HERE]
-    mem[mem[HERE]] = mem[DOCOL]
-    mem[HERE] += 1
+    codeWordAddr = mem[H]
 
-    for wordAddr in wordAddrs
-        mem[mem[HERE]] = wordAddr
-        mem[HERE] += 1
-    end
+    dictWrite(DOCON)
+    dictWrite(val)
 
-    return addr
+    return codeWordAddr
 end
 
 # Threading Primitives (inner interpreter)
 
-NEXT = defPrim("NEXT", () -> begin
+NEXT = defPrim(() -> begin
     reg.W = mem[reg.IP]
     reg.IP += 1
     return mem[reg.W]
-end)
+end, name="NEXT")
 
-DOCOL = defPrim("DOCOL", () -> begin
+DOCOL = defPrim(() -> begin
     pushRS(reg.IP)
     reg.IP = reg.W + 1
-    return mem[NEXT]
-end)
+    return NEXT
+end, name="DOCOL")
+
+DOVAR = defPrim(() -> begin
+    pushPS(reg.W + 1)
+    return NEXT
+end, name="DOVAR")
 
-EXIT = defPrim("EXIT", () -> begin
+DOCON = defPrim(() -> begin
+    pushPS(mem[reg.W + 1])
+    return NEXT
+end, name="DOVAR")
+
+EXIT_CFA = defPrimWord("EXIT", () -> begin
     reg.IP = popRS()
-    return mem[NEXT]
+    return NEXT
 end)
 
+# Dictionary entries for core built-in variables, constants
+
+H_CFA = defExistingVar("H", H)
+
+PSP0_CFA = defConst("PSP0", PSP0)
+RSP0_CFA = defConst("RSP0", RSP0)
+
+defConst("DOCOL", DOCOL)
+defConst("DOCON", DOCON)
+defConst("DOVAR", DOVAR)
+
+defConst("DICT", DICT)
+defConst("MEMSIZE", size_mem)
+
+F_IMMED_CFA = defConst("F_IMMED", F_IMMED)
+F_HIDDEN_CFA = defConst("F_HIDDEN", F_HIDDEN)
+F_LENMASK_CFA = defConst("F_LENMASK", F_LENMASK)
+NFA_MARK_CFA = defConst("NFA_MARK", NFA_MARK)
+
 # Basic forth primitives
 
-DROP = defPrim("DROP", () -> begin
+DROP_CFA = defPrimWord("DROP", () -> begin
     popPS()
-    return mem[NEXT]
+    return NEXT
 end)
 
-SWAP = defPrim("SWAP", () -> begin
+SWAP_CFA = defPrimWord("SWAP", () -> begin
     a = popPS()
     b = popPS()
     pushPS(a)
     pushPS(b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-DUP = defPrim("DUP", () -> begin
+DUP_CFA = defPrimWord("DUP", () -> begin
+    ensurePSDepth(1)
     pushPS(mem[reg.PSP])
-    return mem[NEXT]
+    return NEXT
 end)
 
-OVER = defPrim("OVER", () -> begin
+OVER_CFA = defPrimWord("OVER", () -> begin
     ensurePSDepth(2)
     pushPS(mem[reg.PSP-1])
-    return mem[NEXT]
+    return NEXT
 end)
 
-ROT = defPrim("ROT", () -> begin
+ROT_CFA = defPrimWord("ROT", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
+    pushPS(b)
     pushPS(a)
     pushPS(c)
-    pushPS(b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-NROT = defPrim("-ROT", () -> begin
+NROT_CFA = defPrimWord("-ROT", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
-    pushPS(b)
     pushPS(a)
     pushPS(c)
-    return mem[NEXT]
+    pushPS(b)
+    return NEXT
 end)
 
-TWODROP = defPrim("2DROP", () -> begin
+
+TWODROP_CFA = defPrimWord("2DROP", () -> begin
     popPS()
     popPS()
-    return mem[NEXT]
+    return NEXT
 end)
 
-TWODUP = defPrim("2DUP", () -> begin
+TWODUP_CFA = defPrimWord("2DUP", () -> begin
     ensurePSDepth(2)
     a = mem[reg.PSP-1]
     b = mem[reg.PSP]
     pushPS(a)
     pushPS(b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-TWOSWAP = defPrim("2SWAP", () -> begin
+TWOSWAP_CFA = defPrimWord("2SWAP", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
     d = popPS()
     pushPS(b)
     pushPS(a)
-    pushPS(c)
     pushPS(d)
-    return mem[NEXT]
+    pushPS(c)
+    return NEXT
 end)
 
-QDUP = defPrim("?DUP", () -> begin
+TWOOVER_CFA = defPrimWord("2OVER", () -> begin
+    ensurePSDepth(4)
+    a = mem[reg.PSP-3]
+    b = mem[reg.PSP-2]
+    pushPS(a)
+    pushPS(b)
+    return NEXT
+end)
+
+QDUP_CFA = defPrimWord("?DUP", () -> begin
     ensurePSDepth(1)
     val = mem[reg.PSP]
     if val != 0
         pushPS(val)
     end
-    return mem[NEXT]
+    return NEXT
 end)
 
-INCR = defPrim("1+", () -> begin
+INCR_CFA = defPrimWord("1+", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] += 1
-    return mem[NEXT]
+    return NEXT
 end)
 
-DECR = defPrim("1-", () -> begin
+DECR_CFA = defPrimWord("1-", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] -= 1
-    return mem[NEXT]
+    return NEXT
 end)
 
-INCR2 = defPrim("2+", () -> begin
+INCR2_CFA = defPrimWord("2+", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] += 2
-    return mem[NEXT]
+    return NEXT
 end)
 
-DECR2 = defPrim("2-", () -> begin
+DECR2_CFA = defPrimWord("2-", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] -= 2
-    return mem[NEXT]
+    return NEXT
 end)
 
-ADD = defPrim("+", () -> begin
+ADD_CFA = defPrimWord("+", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a+b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-SUB = defPrim("-", () -> begin
+SUB_CFA = defPrimWord("-", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a-b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-MUL = defPrim("*", () -> begin
+MUL_CFA = defPrimWord("*", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a*b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-DIVMOD = defPrim("/MOD", () -> begin
+DIVMOD_CFA = defPrimWord("/MOD", () -> begin
     b = popPS()
     a = popPS()
     q,r = divrem(a,b)
     pushPS(r)
     pushPS(q)
-    return mem[NEXT]
+    return NEXT
+end)
+
+TWOMUL_CFA = defPrimWord("2*", () -> begin
+    pushPS(popPS() << 1)
+    return NEXT
+end)
+
+TWODIV_CFA = defPrimWord("2/", () -> begin
+    pushPS(popPS() >> 1)
+    return NEXT
 end)
 
-EQU = defPrim("=", () -> begin
+EQ_CFA = defPrimWord("=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a==b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-NEQU = defPrim("<>", () -> begin
+NE_CFA = defPrimWord("<>", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a!=b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-LT = defPrim("<", () -> begin
+LT_CFA = defPrimWord("<", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a<b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-GT = defPrim(">", () -> begin
+GT_CFA = defPrimWord(">", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a>b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-LE = defPrim("<=", () -> begin
+LE_CFA = defPrimWord("<=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a<=b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-GE = defPrim(">=", () -> begin
+GE_CFA = defPrimWord(">=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a>=b ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZEQU = defPrim("0=", () -> begin
+ZE_CFA = defPrimWord("0=", () -> begin
     pushPS(popPS() == 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZNEQU = defPrim("0<>", () -> begin
+ZNE_CFA = defPrimWord("0<>", () -> begin
     pushPS(popPS() != 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZLT = defPrim("0<", () -> begin
+ZLT_CFA = defPrimWord("0<", () -> begin
     pushPS(popPS() < 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZGT = defPrim("0>", () -> begin
+ZGT_CFA = defPrimWord("0>", () -> begin
     pushPS(popPS() > 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZLE = defPrim("0<=", () -> begin
+ZLE_CFA = defPrimWord("0<=", () -> begin
     pushPS(popPS() <= 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZGE = defPrim("0>=", () -> begin
+ZGE_CFA = defPrimWord("0>=", () -> begin
     pushPS(popPS() >= 0 ? -1 : 0)
-    return mem[NEXT]
+    return NEXT
 end)
 
-AND = defPrim("AND", () -> begin
+AND_CFA = defPrimWord("AND", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a & b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-OR = defPrim("OR", () -> begin
+OR_CFA = defPrimWord("OR", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a | b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-XOR = defPrim("XOR", () -> begin
+XOR_CFA = defPrimWord("XOR", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a $ b)
-    return mem[NEXT]
+    return NEXT
 end)
 
-INVERT = defPrim("INVERT", () -> begin
+INVERT_CFA = defPrimWord("INVERT", () -> begin
     pushPS(~popPS())
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Literals
 
-LIT = defPrim("LIT", () -> begin
+LIT_CFA = defPrimWord("LIT", () -> begin
     pushPS(mem[reg.IP])
     reg.IP += 1
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Memory primitives
 
-STORE = defPrim("!", () -> begin
+STORE_CFA = defPrimWord("!", () -> begin
     addr = popPS()
     dat = popPS()
     mem[addr] = dat
-    return mem[NEXT]
+    return NEXT
 end)
 
-FETCH = defPrim("@", () -> begin
+FETCH_CFA = defPrimWord("@", () -> begin
     addr = popPS()
     pushPS(mem[addr])
-    return mem[NEXT]
+    return NEXT
 end)
 
-ADDSTORE = defPrim("+!", () -> begin
+ADDSTORE_CFA = defPrimWord("+!", () -> begin
     addr = popPS()
     toAdd = popPS()
     mem[addr] += toAdd
-    return mem[NEXT]
+    return NEXT
 end)
 
-SUBSTORE = defPrim("-!", () -> begin
+SUBSTORE_CFA = defPrimWord("-!", () -> begin
     addr = popPS()
     toSub = popPS()
     mem[addr] -= toSub
-    return mem[NEXT]
+    return NEXT
 end)
 
 
-# Built-in variables
-
-HERE_CFA = defExistingVar("HERE", HERE)
-LATEST_CFA = defExistingVar("LATEST", LATEST)
-PSP0_CFA = defExistingVar("PSP0", PSP0)
-RSP0_CFA = defExistingVar("RSP0", RSP0)
-STATE, STATE_CFA = defNewVar("STATE", 0)
-BASE, BASE_CFA = defNewVar("BASE", 10)
-
-# Constants
-
-defConst("VERSION", 1)
-defConst("DOCOL", DOCOL)
-defConst("DICT", DICT)
-F_IMMED = defConst("F_IMMED", 128)
-F_HIDDEN = defConst("F_HIDDEN", 256)
-F_LENMASK = defConst("F_LENMASK", 127)
-
 # Return Stack
 
-TOR = defPrim(">R", () -> begin
+TOR_CFA = defPrimWord(">R", () -> begin
     pushRS(popPS())
-    return mem[NEXT]
+    return NEXT
 end)
 
-FROMR = defPrim("R>", () -> begin
+FROMR_CFA = defPrimWord("R>", () -> begin
     pushPS(popRS())
-    return mem[NEXT]
+    return NEXT
 end)
 
-RSPFETCH = defPrim("RSP@", () -> begin
+RFETCH_CFA = defPrimWord("R@", () -> begin
+    pushPS(mem[reg.RSP])
+    return NEXT
+end)
+
+RSPFETCH_CFA = defPrimWord("RSP@", () -> begin
     pushPS(reg.RSP)
-    return mem[NEXT]
+    return NEXT
 end)
 
-RSPSTORE = defPrim("RSP!", () -> begin
-    RSP = popPS()
-    return mem[NEXT]
+RSPSTORE_CFA = defPrimWord("RSP!", () -> begin
+    reg.RSP = popPS()
+    return NEXT
 end)
 
-RDROP = defPrim("RDROP", () -> begin
+RDROP_CFA = defPrimWord("RDROP", () -> begin
     popRS()
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Parameter Stack
 
-PSPFETCH = defPrim("PSP@", () -> begin
+PSPFETCH_CFA = defPrimWord("PSP@", () -> begin
     pushPS(reg.PSP)
-    return mem[NEXT]
+    return NEXT
+end)
+
+PSPSTORE_CFA = defPrimWord("PSP!", () -> begin
+    reg.PSP = popPS()
+    return NEXT
+end)
+
+# Working Register
+
+WFETCH_CFA = defPrimWord("W@", () -> begin
+    pushPS(reg.W)
+    return NEXT
 end)
 
-PSPSTORE = defPrim("PSP!", () -> begin
-    PSP = popPS()
-    return mem[NEXT]
+WSTORE_CFA = defPrimWord("W!", () -> begin
+    reg.W = popPS()
+    return NEXT
 end)
 
 # I/O
 
-defConst("TIB", TIB)
-NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
-TOIN, TOIN_CFA = defNewVar(">IN", 0)
+openFiles = Dict{Int64,IOStream}()
+nextFileID = 1
+SOURCE_ID, SOURCE_ID_CFA = defNewVar("SOURCE-ID", 0)
+
+
+## File access modes
+FAM_RO = 0
+FAM_WO = 1
+FAM_RO_CFA = defConst("R/O", FAM_RO)
+FAM_WO_CFA = defConst("W/O", FAM_WO)
+
+function fileOpener(create::Bool)
+    fnameLen = popPS()
+    fnameAddr = popPS()
+    fam = popPS()
+
+    fname = getString(fnameAddr, fnameLen)
+
+    if create && !isfile(fname)
+        pushPS(0)
+        pushPS(-1) # error
+        return NEXT
+    end
 
-KEY = defPrim("KEY", () -> begin
-    if mem[TOIN] >= mem[NUMTIB]
-        mem[TOIN] = 0
-        line = readline()
-        mem[NUMTIB] = length(line)
-        putString(line, TIB)
+    if (fam == FAM_RO)
+        mode = "r"
+    else
+        mode = "w"
     end
 
-    pushPS(mem[TIB + mem[TOIN]])
-    mem[TOIN] += 1
+    openFiles[nextFileID] = open(fname, mode)
+    pushPS(nextFileID)
+    pushPS(0)
+    
+    nextFileID += 1
+end
+
+OPEN_FILE_CFA = defPrimWord("OPEN-FILE", () -> begin
+    fileOpener(false)
+    return NEXT
+end);
+
+CREATE_FILE_CFA = defPrimWord("CREATE-FILE", () -> begin
+    fileOpener(true)
+    return NEXT
+end);
+
+CLOSE_FILE_CFA = defPrimWord("CLOSE-FILE", () -> begin
+    fid = popPS()
+    close(openFiles[fid])
+    delete!(openFiles, fid)
+    return NEXT
+end)
+
+CLOSE_FILES_CFA = defPrimWord("CLOSE-FILES", () -> begin
+    for fh in values(openFiles)
+        close(fh)
+    end
+    empty!(openFiles)
 
-    return mem[NEXT]
+    return NEXT
 end)
+                              
 
-EMIT = defPrim("EMIT", () -> begin
+EMIT_CFA = defPrimWord("EMIT", () -> begin
     print(Char(popPS()))
-    return mem[NEXT]
+    return NEXT
 end)
 
-WORD = defPrim("WORD", () -> begin
-    
-    c = -1
+function raw_mode!(mode::Bool)
+    if ccall(:jl_tty_set_mode, Int32, (Ptr{Void}, Int32), STDIN.handle, mode) != 0
+        throw("FATAL: Terminal unable to enter raw mode.")
+    end
+end
 
-    skip_to_end = false
-    while true
+function getKey()
+    raw_mode!(true)
+    byte = readbytes(STDIN, 1)[1]
+    raw_mode!(false)
 
-        callPrim(mem[KEY])
-        c = Char(popPS())
+    if byte == 0x0d
+        return 0x0a
+    elseif byte == 127
+        return 0x08
+    else
+        return byte
+    end
+end
 
-        if c == '\\'
-            skip_to_end = true
-            continue
-        end
+KEY_CFA = defPrimWord("KEY", () -> begin
+    pushPS(Int(getKey()))
+    return NEXT
+end)
 
-        if skip_to_end
-            if c == '\n'
-                skip_to_end = false
-            end
-            continue
-        end
+function getLineFromSTDIN()
 
-        if c == ' ' || c == '\t'
-            continue
+    function getFrag(s)
+        chars = collect(s)
+        slashIdx = findlast(chars, '\\')
+
+        if slashIdx > 0
+            return join(chars[slashIdx:length(chars)])
+        else
+            return nothing
         end
+    end
 
-        break
+    function backspaceStr(s, bsCount)
+        oldLen = length(s)
+        newLen = max(0, oldLen - bsCount)
+        return join(collect(s)[1:newLen])
     end
 
-    wordAddr = mem[HERE]
-    offset = 0
+    line = ""
+    while true
+        key = Char(getKey())
+
+        if key == '\n'
+            print(" ")
+            return AbstractString(line)
 
-    if c == '\n'
-        # Treat newline as a special word
+        elseif key == '\x04'
+            if isempty(line)
+                return string("\x04")
+            end
 
-        mem[wordAddr + offset] = Int64(c)
-        pushPS(wordAddr)
-        pushPS(1)
-        return mem[NEXT]
-    end
+        elseif key == '\b'
+            if !isempty(line)
+                print("\b\033[K")
+                line = backspaceStr(line, 1)
+            end
 
-    while true
-        mem[wordAddr + offset] = Int64(c)
-        offset += 1
+        elseif key == '\e'
+            # Strip ANSI escape sequence
+            nextKey = Char(getKey())
+            if nextKey == '['
+                while true
+                    nextKey = Char(getKey())
+                    if nextKey >= '@' || nextKey <= '~'
+                        break
+                    end
+                end
+            end
 
-        callPrim(mem[KEY])
-        c = Char(popPS())
+        elseif key == '\t'
+            # Currently do nothing
+
+            frag = getFrag(line)
+            if frag != nothing
+                if haskey(REPLCompletions.latex_symbols, frag)
+                    print(repeat("\b", length(frag)))
+                    print("\033[K")
+                    comp = REPLCompletions.latex_symbols[frag]
+                    line = string(backspaceStr(line, length(frag)), comp)
+                    print(comp)
+                end
+            end
 
-        if c == ' ' || c == '\t' || c == '\n'
-            # Rewind KEY
-            mem[TOIN] -= 1
-            break
+        else
+            print(key)
+            line = string(line, key)
         end
     end
+end
 
-    wordLen = offset
+SPAN, SPAN_CFA = defNewVar("SPAN", 0)
+EXPECT_CFA = defPrimWord("EXPECT", () -> begin
+    maxLen = popPS()
+    addr = popPS()
 
-    pushPS(wordAddr)
-    pushPS(wordLen)
+    line = getLineFromSTDIN()
 
-    return mem[NEXT]
-end)
+    mem[SPAN] = min(length(line), maxLen)
+    putString(line, addr, maxLen)
 
-NUMBER = defPrim("NUMBER", () -> begin
+    return NEXT
+end)
 
-    wordLen = popPS()
-    wordAddr = popPS()
+BASE, BASE_CFA = defNewVar("BASE", 10)
+NUMBER_CFA = defPrimWord("NUMBER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
 
     s = getString(wordAddr, wordLen)
 
-    try
-        pushPS(parse(Int64, s, mem[BASE]))
-        pushPS(0)
-    catch
-        pushPS(1) # Error indication
-    end
+    pushPS(parse(Int64, s, mem[BASE]))
 
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Dictionary searches
 
-FIND = defPrim("FIND", () -> begin
+FROMLINK_CFA = defPrimWord("LINK>", () -> begin
 
-    wordLen = popPS()
-    wordAddr = popPS()
+    addr = popPS()
+    lenAndFlags = mem[addr+1]
+    len = lenAndFlags & F_LENMASK
+
+    pushPS(addr + 2 + len)
+
+    return NEXT
+end)
+
+NUMCONTEXT, NUMCONTEXT_CFA = defNewVar("#CONTEXT", 1)
+
+createHeader("FORTH", 0)
+FORTH_CFA = mem[H]
+dictWrite(defPrim(() -> begin
+    mem[CONTEXT + mem[NUMCONTEXT] - 1] = reg.W
+    return NEXT
+end, name="FORTH"))
+dictWrite(0) # cell for latest
+
+CURRENT_CFA = defExistingVar("CURRENT", CURRENT)
+
+# Switch to new FORTH vocabulary cfa
+mem[FORTH_CFA+1] = mem[mem[CURRENT]+1]
+mem[CURRENT] = FORTH_CFA
+
+CONTEXT, CONTEXT_CFA = defNewVar("CONTEXT", zeros(Int64, 10))
+mem[CONTEXT] = FORTH_CFA
+
+FINDVOCAB_CFA = defPrimWord("FINDVOCAB", () -> begin
+    vocabCFA = popPS()
+    countedAddr = popPS()
+
+    wordAddr = countedAddr + 1
+    wordLen = mem[countedAddr]
     word = lowercase(getString(wordAddr, wordLen))
 
-    latest = LATEST
-    
-    i = 0
-    while (latest = mem[latest]) > 0
-        lenAndFlags = mem[latest+1]
+    lfa = vocabCFA+1
+    lenAndFlags = 0
+
+    while (lfa = mem[lfa]) > 0
+
+        lenAndFlags = mem[lfa+1]
         len = lenAndFlags & F_LENMASK
         hidden = (lenAndFlags & F_HIDDEN) == F_HIDDEN
 
         if hidden || len != wordLen
             continue
         end
-        
-        thisAddr = latest+2
-        thisWord = lowercase(getString(thisAddr, len))
 
-        if lowercase(thisWord) == lowercase(word)
+        thisWord = lowercase(getString(lfa+2, len))
+
+        if thisWord == word
             break
         end
     end
 
-    pushPS(latest)
-
-    return mem[NEXT]
-end)
-
-TOCFA = defPrim(">CFA", () -> begin
-
-    addr = popPS()
-    lenAndFlags = mem[addr+1]
-    len = lenAndFlags & F_LENMASK
-
-    pushPS(addr + 2 + len)
+    if lfa > 0
+        pushPS(lfa)
+        callPrim(mem[FROMLINK_CFA])
+        if (lenAndFlags & F_IMMED) == F_IMMED
+            pushPS(1)
+        else
+            pushPS(-1)
+        end
+    else
+        pushPS(countedAddr)
+        pushPS(0)
+    end
 
-    return mem[NEXT]
+    return NEXT
 end)
 
-TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
-
-# Compilation
-
-CREATE = defPrim("CREATE", () -> begin
+FIND_CFA = defPrimWord("FIND", () -> begin
 
-    wordLen = popPS()
-    wordAddr = popPS()
-    word = getString(wordAddr, wordLen)
+    countedAddr = popPS()
+    context = mem[CONTEXT:(CONTEXT+mem[NUMCONTEXT]-1)]
 
-    createHeader(word, 0)
+    for vocabCFA in reverse(context)
+        pushPS(countedAddr)
+        pushPS(vocabCFA)
+        callPrim(mem[FINDVOCAB_CFA])
 
-    return mem[NEXT]
-end)
+        callPrim(mem[DUP_CFA])
+        if popPS() != 0
+            return NEXT
+        else
+            popPS()
+            popPS()
+        end
+    end
 
-COMMA = defPrim(",", () -> begin
-    mem[mem[HERE]] = popPS()
-    mem[HERE] += 1
+    pushPS(countedAddr)
+    pushPS(0)
 
-    return mem[NEXT]
+    return NEXT
 end)
 
-LBRAC = defPrim("[", () -> begin
-    mem[STATE] = 0
-    return mem[NEXT]
-end, flags=F_IMMED)
-
-RBRAC = defPrim("]", () -> begin
-    mem[STATE] = 1
-    return mem[NEXT]
-end, flags=F_IMMED)
-
-HIDDEN = defPrim("HIDDEN", () -> begin
-    addr = popPS() + 1
-    mem[addr] = mem[addr] $ F_HIDDEN
-    return mem[NEXT]
-end)
-
-HIDE = defWord("HIDE",
-    [WORD,
-    FIND,
-    HIDDEN,
-    EXIT])
-
-COLON = defWord(":",
-    [WORD,
-    CREATE,
-    LIT, DOCOL, COMMA,
-    LATEST, FETCH, HIDDEN,
-    RBRAC,
-    EXIT])
-
-SEMICOLON = defWord(";",
-    [LIT, EXIT, COMMA,
-    LATEST, FETCH, HIDDEN,
-    LBRAC,
-    EXIT], flags=F_IMMED)
-
-IMMEDIATE = defPrim("IMMEDIATE", () -> begin
-    lenAndFlagsAddr = mem[LATEST] + 1
-    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
-    return mem[NEXT]
-end, flags=F_IMMED)
-
-TICK = defWord("'", [WORD, FIND, TOCFA, EXIT])
 
 # Branching
 
-BRANCH = defPrim("BRANCH", () -> begin
+BRANCH_CFA = defPrimWord("BRANCH", () -> begin
     reg.IP += mem[reg.IP]
-    return mem[NEXT]
+    return NEXT
 end)
 
-ZBRANCH = defPrim("0BRANCH", () -> begin
+ZBRANCH_CFA = defPrimWord("0BRANCH", () -> begin
     if (popPS() == 0)
         reg.IP += mem[reg.IP]
     else
         reg.IP += 1
     end
 
-    return mem[NEXT]
+    return NEXT
 end)
 
 # Strings
 
-LITSTRING = defPrim("LITSTRING", () -> begin
+LITSTRING_CFA = defPrimWord("LITSTRING", () -> begin
     len = mem[reg.IP]
     reg.IP += 1
     pushPS(reg.IP)
     pushPS(len)
     reg.IP += len
 
-    return mem[NEXT]
+    return NEXT
 end)
 
-TELL = defPrim("TELL", () -> begin
+TYPE_CFA = defPrimWord("TYPE", () -> begin
     len = popPS()
     addr = popPS()
     str = getString(addr, len)
     print(str)
-    return mem[NEXT]
+    return NEXT
 end)
 
-# Outer interpreter
+# Interpreter/Compiler-specific I/O
+
+TIB_CFA = defConst("TIB", TIB)
+NUMTIB, NUMTIB_CFA = defNewVar("#TIB", 0)
+TOIN, TOIN_CFA = defNewVar(">IN", 0)
+
+QUERY_CFA = defWord("QUERY",
+    [TIB_CFA, LIT_CFA, 160, EXPECT_CFA,
+    SPAN_CFA, FETCH_CFA, NUMTIB_CFA, STORE_CFA,
+    LIT_CFA, 0, TOIN_CFA, STORE_CFA,
+    EXIT_CFA])
 
-INTERPRET = defPrim("INTERPRET", () -> begin
+WORD_CFA = defPrimWord("WORD", () -> begin
+    delim = popPS()
 
-    callPrim(mem[WORD])
+    # Chew up initial occurrences of delim
+    while (mem[TOIN]<mem[NUMTIB] && mem[TIB+mem[TOIN]] == delim)
+        mem[TOIN] += 1
+    end
 
-    wordName = getString(mem[reg.PSP-1], mem[reg.PSP])
-    println("... ", replace(wordName, "\n", "\\n"), " ...")
+    countAddr = mem[H]
+    addr = mem[H]+1
 
-    callPrim(mem[TWODUP])
-    callPrim(mem[FIND])
+    # Start reading in word
+    count = 0
+    while (mem[TOIN]<mem[NUMTIB])
+        mem[addr] = mem[TIB+mem[TOIN]]
+        mem[TOIN] += 1
 
-    wordAddr = mem[reg.PSP]
+        if (mem[addr] == delim)
+            break
+        end
 
+        count += 1
+        addr += 1
+    end
 
-    if wordAddr>0
-        # Word in dictionary
+    # Record count
+    mem[countAddr] = count
+    pushPS(countAddr)
 
-        isImmediate = (mem[wordAddr+1] & F_IMMED) != 0
-        callPrim(mem[TOCFA])
+    return NEXT
+end)
 
-        callPrim(mem[ROT]) # get rid of extra copy of word string details
-        popPS()
-        popPS()
+# Compilation
 
-        if mem[STATE] == 0 || isImmediate
-            # Execute!
-            return mem[popPS()]
-        else
-            # Append CFA to dictionary
-            callPrim(mem[COMMA])
-        end
-    else
-        # Not in dictionary, assume number
+STATE, STATE_CFA = defNewVar("STATE", 0)
 
-        popPS()
+COMMA_CFA = defPrimWord(",", () -> begin
+    mem[mem[H]] = popPS()
+    mem[H] += 1
 
-        callPrim(mem[NUMBER])
+    return NEXT
+end)
 
-        if popPS() != 0
-            println("Parse error at word: '$wordName'")
-            return mem[NEXT]
-        else
+HERE_CFA = defWord("HERE",
+    [H_CFA, FETCH_CFA, EXIT_CFA])
+
+HEADER_CFA = defPrimWord("HEADER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
+    word = getString(wordAddr, wordLen)
+
+    createHeader(word, 0)
+
+    return NEXT
+end)
+
+CREATE_CFA = defWord("CREATE",
+    [LIT_CFA, 32, WORD_CFA, HEADER_CFA,
+    LIT_CFA, DOVAR, COMMA_CFA,
+    EXIT_CFA])
+
+DODOES = defPrim(() -> begin
+    pushRS(reg.IP)
+    reg.IP = popPS()
+    pushPS(reg.W + 1)
+    return NEXT
+end, name="DODOES")
+
+DOES_HELPER_CFA = defPrimWord("(DOES>)", () -> begin
+
+    pushPS(mem[mem[CURRENT]+1])
+    callPrim(mem[FROMLINK_CFA])
+    cfa = popPS()
+
+    runtimeAddr = popPS()
+
+    mem[cfa] = defPrim(eval(:(() -> begin
+        pushPS($(runtimeAddr))
+        return DODOES
+    end)), name="doesPrim")
+
+    return NEXT
+end, flags=F_IMMED | F_HIDDEN)
+
+DOES_CFA = defWord("DOES>",
+    [LIT_CFA, LIT_CFA, COMMA_CFA, HERE_CFA, LIT_CFA, 3, ADD_CFA, COMMA_CFA,
+    LIT_CFA, DOES_HELPER_CFA, COMMA_CFA, LIT_CFA, EXIT_CFA, COMMA_CFA, EXIT_CFA],
+    flags=F_IMMED)
+
+LBRAC_CFA = defPrimWord("[", () -> begin
+    mem[STATE] = 0
+    return NEXT
+end, flags=F_IMMED)
+
+RBRAC_CFA = defPrimWord("]", () -> begin
+    mem[STATE] = 1
+    return NEXT
+end, flags=F_IMMED)
+
+HIDDEN_CFA = defPrimWord("HIDDEN", () -> begin
+    lenAndFlagsAddr = mem[mem[CURRENT]+1] + 1
+    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_HIDDEN
+    return NEXT
+end)
+
+COLON_CFA = defWord(":",
+    [LIT_CFA, 32, WORD_CFA,
+    HEADER_CFA,
+    LIT_CFA, DOCOL, COMMA_CFA,
+    HIDDEN_CFA,
+    RBRAC_CFA,
+    EXIT_CFA])
+
+SEMICOLON_CFA = defWord(";",
+    [LIT_CFA, EXIT_CFA, COMMA_CFA,
+    HIDDEN_CFA,
+    LBRAC_CFA,
+    EXIT_CFA], flags=F_IMMED)
+
+IMMEDIATE_CFA = defPrimWord("IMMEDIATE", () -> begin
+    lenAndFlagsAddr = mem[mem[CURRENT]+1] + 1
+    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
+    return NEXT
+end, flags=F_IMMED)
+
+CODE_CFA = defPrimWord("CODE", () -> begin
+    pushPS(32)
+    callPrim(mem[WORD_CFA])
+    callPrim(mem[HEADER_CFA])
+
+    exprString = "() -> begin\n"
+    while true
+        if mem[TOIN] >= mem[NUMTIB]
+            exprString = string(exprString, "\n")
+            if currentSource() == STDIN
+                println()
+            end
+
+            pushPS(TIB)
+            pushPS(160)
+            callPrim(mem[EXPECT_CFA])
+            mem[NUMTIB] = mem[SPAN]
+            mem[TOIN] = 0
         end
 
-        if mem[STATE] == 0
-            # Number already on stack!
-        else
-            # Append literal to dictionary
-            pushPS(LIT)
-            callPrim(mem[COMMA])
-            callPrim(mem[COMMA])
+        pushPS(32)
+        callPrim(mem[WORD_CFA])
+        cAddr = popPS()
+        thisWord = getString(cAddr+1, mem[cAddr])
+
+        if uppercase(thisWord) == "END-CODE"
+            break
         end
+
+        exprString = string(exprString, " ", thisWord)
     end
+    exprString = string(exprString, "\nreturn NEXT\nend")
 
-    return mem[NEXT]
+    func = eval(parse(exprString))
+    dictWrite(defPrim(func))
+
+    return NEXT
 end)
 
-QUIT = defWord("QUIT",
-    [RSP0_CFA, RSPSTORE,
-    INTERPRET,
-    BRANCH,-2])
+# Outer Interpreter
 
-NL = defPrim("\n", () -> begin
-    if mem[STATE] == 0
-        println(" ok")
-    end
-    return mem[NEXT]
+EXECUTE_CFA = defPrimWord("EXECUTE", () -> begin
+    reg.W = popPS()
+    return mem[reg.W]
 end)
 
-# Odds and Ends
+INTERPRET_CFA = defWord("INTERPRET",
+    [LIT_CFA, 32, WORD_CFA, # Read next space-delimited word
 
-CHAR = defPrim("CHAR", () -> begin
-    callPrim(mem[WORD])
-    wordLen = popPS()
-    wordAddr = popPS()
-    word = getString(wordAddr, wordLen)
-    pushPS(Int64(word[1]))
+    DUP_CFA, FETCH_CFA, ZE_CFA, ZBRANCH_CFA, 3,
+        DROP_CFA, EXIT_CFA, # Exit if TIB is exhausted
 
-    return mem[NEXT]
-end)
+    STATE_CFA, FETCH_CFA, ZBRANCH_CFA, 24,
+        # Compiling
+        FIND_CFA, QDUP_CFA, ZBRANCH_CFA, 13,
+
+            # Found word. 
+            LIT_CFA, -1, EQ_CFA, INVERT_CFA, ZBRANCH_CFA, 4,
+
+                # Immediate: Execute!
+                EXECUTE_CFA, BRANCH_CFA, -26,
+
+                # Not immediate: Compile!
+                COMMA_CFA, BRANCH_CFA, -29,
+
+            # No word found, parse number
+            NUMBER_CFA, LIT_CFA, LIT_CFA, COMMA_CFA, COMMA_CFA, BRANCH_CFA, -36,
+        
+       # Interpreting
+        FIND_CFA, QDUP_CFA, ZBRANCH_CFA, 5,
 
-EXECUTE = defPrim("EXECUTE", () -> begin
-    return mem[popPS()]
+            # Found word. Execute!
+            DROP_CFA, EXECUTE_CFA, BRANCH_CFA, -44,
+
+            # No word found, parse number and leave on stack
+            NUMBER_CFA, BRANCH_CFA, -47,
+    EXIT_CFA])
+
+PROMPT_CFA = defPrimWord("PROMPT", () -> begin
+    if mem[STATE] == 0
+        print(" ok")
+    end
+    println()
+
+    return NEXT
 end)
 
-BYE = defPrim("BYE", () -> begin
+QUIT_CFA = defWord("QUIT",
+    [LIT_CFA, 0, STATE_CFA, STORE_CFA,
+    LIT_CFA, 0, NUMTIB_CFA, STORE_CFA,
+    RSP0_CFA, RSPSTORE_CFA,
+    QUERY_CFA,
+    INTERPRET_CFA, PROMPT_CFA,
+    BRANCH_CFA,-4])
+
+ABORT_CFA = defWord("ABORT",
+    [CLOSE_FILES_CFA, PSP0_CFA, PSPSTORE_CFA, QUIT_CFA])
+
+BYE_CFA = defPrimWord("BYE", () -> begin
+    println("\nBye!")
     return 0
 end)
 
 #### VM loop ####
-function runVM()
+
+initialized = false
+initFileName = nothing
+if isfile("lib.4th")
+    initFileName = "lib.4th"
+elseif isfile(Pkg.dir("forth","src", "lib.4th"))
+    initFileName = Pkg.dir("forth","src","lib.4th")
+end
+
+function run(;initialize=true)
+
+    global initialized, initFileName
+    if !initialized && initialize
+        if initFileName != nothing
+            print("Including definitions from $initFileName...")
+
+            # TODO
+
+            initialized = true
+        else
+            println("No library file found. Only primitive words available.")
+        end
+    end
+
     # Start with IP pointing to first instruction of outer interpreter
-    reg.IP = QUIT + 1
+    reg.IP = QUIT_CFA + 1
 
     # Primitive processing loop.
     # Everyting else is simply a consequence of this loop!
-    jmp = mem[NEXT]
-    while (jmp = callPrim(jmp)) != 0
-        println("Evaluating prim $jmp [$(primNames[-jmp])]")
+    jmp = NEXT
+    while jmp != 0
+        try
+            #println("Entering prim $(getPrimName(jmp))")
+            jmp = callPrim(jmp)
+
+        catch ex
+            showerror(STDOUT, ex)
+            println()
+
+            # QUIT
+            reg.IP = ABORT_CFA + 1
+            jmp = NEXT
+        end
     end
 end
 
 # Debugging tools
 
+TRACE_CFA = defPrimWord("TRACE", () -> begin
+    println("reg.W: $(reg.W) reg.IP: $(reg.IP)")
+    print("PS: "); printPS()
+    print("RS: "); printRS()
+    print("[paused]")
+    readline()
+
+    return NEXT
+end)
+
 function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
     chars = Array{Char,1}(cellsPerLine)
 
@@ -916,16 +1257,16 @@ function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
             i += 1
         end
 
-        println("\t", ASCIIString(chars))
+        println("\t", AbstractString(chars))
     end
 end
 
 function printPS()
-    count = reg.PSP - mem[PSP0]
+    count = reg.PSP - PSP0
 
     if count > 0
         print("<$count>")
-        for i in (mem[PSP0]+1):reg.PSP
+        for i in (PSP0+1):reg.PSP
             print(" $(mem[i])")
         end
         println()
@@ -935,11 +1276,11 @@ function printPS()
 end
 
 function printRS()
-    count = reg.RSP - mem[RSP0]
+    count = reg.RSP - RSP0
 
     if count > 0
         print("<$count>")
-        for i in (mem[RSP0]+1):reg.RSP
+        for i in (RSP0+1):reg.RSP
             print(" $(mem[i])")
         end
         println()
@@ -948,4 +1289,14 @@ function printRS()
     end
 end
 
+DUMP = defPrimWord("DUMP", () -> begin
+    count = popPS()
+    addr = popPS()
+
+    println()
+    dump(addr, count=count)
+
+    return NEXT
+end)
+
 end