X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=forth.jl.git;a=blobdiff_plain;f=src%2Fforth.jl;h=9439dead46913871d9255834a9272713cad19433;hp=1ed96c85458612623a8faffc22372f1c5cdaba22;hb=6cb12b03e2a154214fc60d7c437e650e79fb42e5;hpb=3502b666bc5c477f928d71f84049b7e5ef43ca0d

diff --git a/src/forth.jl b/src/forth.jl
index 1ed96c8..9439dea 100644
--- a/src/forth.jl
+++ b/src/forth.jl
@@ -1,34 +1,14 @@
 module forth
 
 # 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 as negative indicies
-# into the primitives array which contains 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}()
@@ -36,18 +16,16 @@ primNames = Array{ASCIIString,1}()
 # Built-in variables
 
 nextVarAddr = 1
-RSP0 = nextVarAddr; nextVarAddr += 1
-PSP0 = nextVarAddr; nextVarAddr += 1
-HERE = nextVarAddr; nextVarAddr += 1
+H = nextVarAddr; nextVarAddr += 1
 LATEST = nextVarAddr; nextVarAddr += 1
 
-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[LATEST] = 0                     # no previous definition
 
-DICT = mem[HERE] # Save bottom of dictionary as constant
+DICT = mem[H] # Save bottom of dictionary as constant
 
 # VM registers
 type Reg
@@ -55,27 +33,20 @@ type Reg
     PSP::Int64  # Parameter/data stack pointer
     IP::Int64   # Instruction pointer
     W::Int64    # Working register
-
-    source::Any # Input stream in use
 end
-reg = Reg(mem[RSP0], mem[PSP0], 0, 0, STDIN)
+reg = Reg(RSP0, PSP0, 0, 0)
 
 # Stack manipulation functions
 
-type StackUnderflow <: Exception end
-
-getRSDepth() = reg.RSP - mem[RSP0]
-getPSDepth() = reg.PSP - mem[PSP0]
-
 function ensurePSDepth(depth::Int64)
-    if getPSDepth()<depth
-        throw(StackUnderflow())
+    if reg.PSP - PSP0 < depth
+        error("Parameter stack underflow.")
     end
 end
 
 function ensureRSDepth(depth::Int64)
-    if getRSDepth()<depth
-        throw(StackUnderflow())
+    if reg.RSP - RSP0 < depth
+        error("Return stack underflow.")
     end
 end
 
@@ -106,6 +77,7 @@ 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]
 end
@@ -114,30 +86,42 @@ end
 
 function defPrim(f::Function; name="nameless")
     push!(primitives, f)
-    push!(primNames, name)
+    push!(primNames, replace(name, "\004", "EOF"))
 
     return -length(primitives)
 end
 
-callPrim(addr::Int64) = primitives[-addr]()
+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
+# Word creation functions
+
+F_LENMASK = 31
+F_IMMED = 32
+F_HIDDEN = 64
+NFA_MARK = 128
 
 function createHeader(name::AbstractString, flags::Int64)
-    mem[mem[HERE]] = mem[LATEST]
-    mem[LATEST] = mem[HERE]
-    mem[HERE] += 1
+    mem[mem[H]] = mem[LATEST]
+    mem[LATEST] = mem[H]
+    mem[H] += 1
 
-    mem[mem[HERE]] = length(name) | flags; mem[HERE] += 1
-    putString(name, mem[HERE]); mem[HERE] += length(name)
+    mem[mem[H]] = length(name) | flags | NFA_MARK; mem[H] += 1
+    putString(name, mem[H]); mem[H] += length(name)
 end
 
 function defPrimWord(name::AbstractString, f::Function; flags::Int64=0)
     createHeader(name, flags)
 
-    codeWordAddr = mem[HERE]
+    codeWordAddr = mem[H]
     mem[codeWordAddr] = defPrim(f, name=name)
-    mem[HERE] += 1
+    mem[H] += 1
 
     return codeWordAddr
 end
@@ -145,19 +129,19 @@ end
 function defWord(name::AbstractString, wordAddrs::Array{Int64,1}; flags::Int64=0)
     createHeader(name, flags)
 
-    addr = mem[HERE]
-    mem[mem[HERE]] = DOCOL
-    mem[HERE] += 1
+    addr = mem[H]
+    mem[mem[H]] = DOCOL
+    mem[H] += 1
 
     for wordAddr in wordAddrs
-        mem[mem[HERE]] = wordAddr
-        mem[HERE] += 1
+        mem[mem[H]] = wordAddr
+        mem[H] += 1
     end
 
     return addr
 end
 
-# Variable creation
+# Variable creation functions
 
 function defExistingVar(name::AbstractString, varAddr::Int64; flags::Int64=0)
 
@@ -170,27 +154,24 @@ end
 function defNewVar(name::AbstractString, initial::Int64; flags::Int64=0)
     createHeader(name, flags)
     
-    codeWordAddr = mem[HERE]
-    varAddr = mem[HERE] + 1
+    codeWordAddr = mem[H]
+    varAddr = mem[H] + 1
 
-    f = eval(:(() -> begin
-        pushPS($(varAddr))
-        return NEXT
-    end))
-
-    mem[mem[HERE]] = defPrim(f, name=name); mem[HERE] += 1
-    mem[mem[HERE]] = initial; mem[HERE] += 1
+    mem[mem[H]] = DOVAR; mem[H] += 1
+    mem[mem[H]] = initial; mem[H] += 1
 
     return varAddr, codeWordAddr
 end
 
 function defConst(name::AbstractString, val::Int64; flags::Int64=0)
-    defPrimWord(name, eval(:(() -> begin
-        pushPS($(val))
-        return NEXT
-    end)))
+    createHeader(name, flags)
 
-    return val
+    codeWordAddr = mem[H]
+
+    mem[mem[H]] = DOCON; mem[H] += 1
+    mem[mem[H]] = val; mem[H] += 1
+
+    return codeWordAddr
 end
 
 # Threading Primitives (inner interpreter)
@@ -207,19 +188,49 @@ DOCOL = defPrim(() -> begin
     return NEXT
 end, name="DOCOL")
 
-EXIT = defPrimWord("EXIT", () -> begin
+DOVAR = defPrim(() -> begin
+    pushPS(reg.W + 1)
+    return NEXT
+end, name="DOVAR")
+
+DOCON = defPrim(() -> begin
+    pushPS(mem[reg.W + 1])
+    return NEXT
+end, name="DOVAR")
+
+EXIT_CFA = defPrimWord("EXIT", () -> begin
     reg.IP = popRS()
     return NEXT
 end)
 
+# Dictionary entries for core built-in variables, constants
+
+H_CFA = defExistingVar("H", H)
+LATEST_CFA = defExistingVar("LATEST", LATEST)
+
+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 = defPrimWord("DROP", () -> begin
+DROP_CFA = defPrimWord("DROP", () -> begin
     popPS()
     return NEXT
 end)
 
-SWAP = defPrimWord("SWAP", () -> begin
+SWAP_CFA = defPrimWord("SWAP", () -> begin
     a = popPS()
     b = popPS()
     pushPS(a)
@@ -227,44 +238,46 @@ SWAP = defPrimWord("SWAP", () -> begin
     return NEXT
 end)
 
-DUP = defPrimWord("DUP", () -> begin
+DUP_CFA = defPrimWord("DUP", () -> begin
+    ensurePSDepth(1)
     pushPS(mem[reg.PSP])
     return NEXT
 end)
 
-OVER = defPrimWord("OVER", () -> begin
+OVER_CFA = defPrimWord("OVER", () -> begin
     ensurePSDepth(2)
     pushPS(mem[reg.PSP-1])
     return NEXT
 end)
 
-ROT = defPrimWord("ROT", () -> begin
+ROT_CFA = defPrimWord("ROT", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
+    pushPS(b)
     pushPS(a)
     pushPS(c)
-    pushPS(b)
     return NEXT
 end)
 
-NROT = defPrimWord("-ROT", () -> begin
+NROT_CFA = defPrimWord("-ROT", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
-    pushPS(b)
     pushPS(a)
     pushPS(c)
+    pushPS(b)
     return NEXT
 end)
 
-TWODROP = defPrimWord("2DROP", () -> begin
+
+TWODROP_CFA = defPrimWord("2DROP", () -> begin
     popPS()
     popPS()
     return NEXT
 end)
 
-TWODUP = defPrimWord("2DUP", () -> begin
+TWODUP_CFA = defPrimWord("2DUP", () -> begin
     ensurePSDepth(2)
     a = mem[reg.PSP-1]
     b = mem[reg.PSP]
@@ -273,19 +286,28 @@ TWODUP = defPrimWord("2DUP", () -> begin
     return NEXT
 end)
 
-TWOSWAP = defPrimWord("2SWAP", () -> begin
+TWOSWAP_CFA = defPrimWord("2SWAP", () -> begin
     a = popPS()
     b = popPS()
     c = popPS()
     d = popPS()
     pushPS(b)
     pushPS(a)
-    pushPS(c)
     pushPS(d)
+    pushPS(c)
     return NEXT
 end)
 
-QDUP = defPrimWord("?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
@@ -294,52 +316,52 @@ QDUP = defPrimWord("?DUP", () -> begin
     return NEXT
 end)
 
-INCR = defPrimWord("1+", () -> begin
+INCR_CFA = defPrimWord("1+", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] += 1
     return NEXT
 end)
 
-DECR = defPrimWord("1-", () -> begin
+DECR_CFA = defPrimWord("1-", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] -= 1
     return NEXT
 end)
 
-INCR2 = defPrimWord("2+", () -> begin
+INCR2_CFA = defPrimWord("2+", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] += 2
     return NEXT
 end)
 
-DECR2 = defPrimWord("2-", () -> begin
+DECR2_CFA = defPrimWord("2-", () -> begin
     ensurePSDepth(1)
     mem[reg.PSP] -= 2
     return NEXT
 end)
 
-ADD = defPrimWord("+", () -> begin
+ADD_CFA = defPrimWord("+", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a+b)
     return NEXT
 end)
 
-SUB = defPrimWord("-", () -> begin
+SUB_CFA = defPrimWord("-", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a-b)
     return NEXT
 end)
 
-MUL = defPrimWord("*", () -> begin
+MUL_CFA = defPrimWord("*", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a*b)
     return NEXT
 end)
 
-DIVMOD = defPrimWord("/MOD", () -> begin
+DIVMOD_CFA = defPrimWord("/MOD", () -> begin
     b = popPS()
     a = popPS()
     q,r = divrem(a,b)
@@ -348,107 +370,117 @@ DIVMOD = defPrimWord("/MOD", () -> begin
     return NEXT
 end)
 
-EQU = defPrimWord("=", () -> begin
+TWOMUL_CFA = defPrimWord("2*", () -> begin
+    pushPS(popPS() << 1)
+    return NEXT
+end)
+
+TWODIV_CFA = defPrimWord("2/", () -> begin
+    pushPS(popPS() >> 1)
+    return NEXT
+end)
+
+EQ_CFA = defPrimWord("=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a==b ? -1 : 0)
     return NEXT
 end)
 
-NEQU = defPrimWord("<>", () -> begin
+NE_CFA = defPrimWord("<>", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a!=b ? -1 : 0)
     return NEXT
 end)
 
-LT = defPrimWord("<", () -> begin
+LT_CFA = defPrimWord("<", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a<b ? -1 : 0)
     return NEXT
 end)
 
-GT = defPrimWord(">", () -> begin
+GT_CFA = defPrimWord(">", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a>b ? -1 : 0)
     return NEXT
 end)
 
-LE = defPrimWord("<=", () -> begin
+LE_CFA = defPrimWord("<=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a<=b ? -1 : 0)
     return NEXT
 end)
 
-GE = defPrimWord(">=", () -> begin
+GE_CFA = defPrimWord(">=", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a>=b ? -1 : 0)
     return NEXT
 end)
 
-ZEQU = defPrimWord("0=", () -> begin
+ZE_CFA = defPrimWord("0=", () -> begin
     pushPS(popPS() == 0 ? -1 : 0)
     return NEXT
 end)
 
-ZNEQU = defPrimWord("0<>", () -> begin
+ZNE_CFA = defPrimWord("0<>", () -> begin
     pushPS(popPS() != 0 ? -1 : 0)
     return NEXT
 end)
 
-ZLT = defPrimWord("0<", () -> begin
+ZLT_CFA = defPrimWord("0<", () -> begin
     pushPS(popPS() < 0 ? -1 : 0)
     return NEXT
 end)
 
-ZGT = defPrimWord("0>", () -> begin
+ZGT_CFA = defPrimWord("0>", () -> begin
     pushPS(popPS() > 0 ? -1 : 0)
     return NEXT
 end)
 
-ZLE = defPrimWord("0<=", () -> begin
+ZLE_CFA = defPrimWord("0<=", () -> begin
     pushPS(popPS() <= 0 ? -1 : 0)
     return NEXT
 end)
 
-ZGE = defPrimWord("0>=", () -> begin
+ZGE_CFA = defPrimWord("0>=", () -> begin
     pushPS(popPS() >= 0 ? -1 : 0)
     return NEXT
 end)
 
-AND = defPrimWord("AND", () -> begin
+AND_CFA = defPrimWord("AND", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a & b)
     return NEXT
 end)
 
-OR = defPrimWord("OR", () -> begin
+OR_CFA = defPrimWord("OR", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a | b)
     return NEXT
 end)
 
-XOR = defPrimWord("XOR", () -> begin
+XOR_CFA = defPrimWord("XOR", () -> begin
     b = popPS()
     a = popPS()
     pushPS(a $ b)
     return NEXT
 end)
 
-INVERT = defPrimWord("INVERT", () -> begin
+INVERT_CFA = defPrimWord("INVERT", () -> begin
     pushPS(~popPS())
     return NEXT
 end)
 
 # Literals
 
-LIT = defPrimWord("LIT", () -> begin
+LIT_CFA = defPrimWord("LIT", () -> begin
     pushPS(mem[reg.IP])
     reg.IP += 1
     return NEXT
@@ -456,27 +488,27 @@ end)
 
 # Memory primitives
 
-STORE = defPrimWord("!", () -> begin
+STORE_CFA = defPrimWord("!", () -> begin
     addr = popPS()
     dat = popPS()
     mem[addr] = dat
     return NEXT
 end)
 
-FETCH = defPrimWord("@", () -> begin
+FETCH_CFA = defPrimWord("@", () -> begin
     addr = popPS()
     pushPS(mem[addr])
     return NEXT
 end)
 
-ADDSTORE = defPrimWord("+!", () -> begin
+ADDSTORE_CFA = defPrimWord("+!", () -> begin
     addr = popPS()
     toAdd = popPS()
     mem[addr] += toAdd
     return NEXT
 end)
 
-SUBSTORE = defPrimWord("-!", () -> begin
+SUBSTORE_CFA = defPrimWord("-!", () -> begin
     addr = popPS()
     toSub = popPS()
     mem[addr] -= toSub
@@ -484,197 +516,202 @@ SUBSTORE = defPrimWord("-!", () -> begin
 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 = defPrimWord(">R", () -> begin
+TOR_CFA = defPrimWord(">R", () -> begin
     pushRS(popPS())
     return NEXT
 end)
 
-FROMR = defPrimWord("R>", () -> begin
+FROMR_CFA = defPrimWord("R>", () -> begin
     pushPS(popRS())
     return NEXT
 end)
 
-RSPFETCH = defPrimWord("RSP@", () -> begin
+RFETCH_CFA = defPrimWord("R@", () -> begin
+    pushPS(mem[reg.RSP])
+    return NEXT
+end)
+
+RSPFETCH_CFA = defPrimWord("RSP@", () -> begin
     pushPS(reg.RSP)
     return NEXT
 end)
 
-RSPSTORE = defPrimWord("RSP!", () -> begin
-    RSP = popPS()
+RSPSTORE_CFA = defPrimWord("RSP!", () -> begin
+    reg.RSP = popPS()
     return NEXT
 end)
 
-RDROP = defPrimWord("RDROP", () -> begin
+RDROP_CFA = defPrimWord("RDROP", () -> begin
     popRS()
     return NEXT
 end)
 
 # Parameter Stack
 
-PSPFETCH = defPrimWord("PSP@", () -> begin
+PSPFETCH_CFA = defPrimWord("PSP@", () -> begin
     pushPS(reg.PSP)
     return NEXT
 end)
 
-PSPSTORE = defPrimWord("PSP!", () -> begin
-    PSP = popPS()
+PSPSTORE_CFA = defPrimWord("PSP!", () -> begin
+    reg.PSP = popPS()
     return NEXT
 end)
 
 # Working Register
 
-WFETCH = defPrimWord("W@", () -> begin
+WFETCH_CFA = defPrimWord("W@", () -> begin
     pushPS(reg.W)
     return NEXT
 end)
 
-WSTORE = defPrimWord("W!", () -> begin
+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)
-EOF = defConst("EOF", 4)
+sources = Array{Any,1}()
+currentSource() = sources[length(sources)]
 
-KEY = defPrimWord("KEY", () -> begin
-    if mem[TOIN] >= mem[NUMTIB]
-        mem[TOIN] = 0
-
-        if !eof(reg.source)
-            line = readline(reg.source)
-            mem[NUMTIB] = length(line)
-            putString(line, TIB)
-        else
-            mem[NUMTIB] = 1
-            mem[TIB] = EOF
-        end
+EOF_CFA = defPrimWord("\x04", () -> begin
+    if currentSource() != STDIN
+        close(pop!(sources))
+        return NEXT
+    else
+        return 0
     end
-
-    pushPS(mem[TIB + mem[TOIN]])
-    mem[TOIN] += 1
-
-    return NEXT
 end)
 
-EMIT = defPrimWord("EMIT", () -> begin
+EMIT_CFA = defPrimWord("EMIT", () -> begin
     print(Char(popPS()))
     return NEXT
 end)
 
-WORD = defPrimWord("WORD", () -> begin
+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
 
-    eof_char = Char(EOF)
-    c = eof_char
+function getKey()
+    raw_mode!(true)
+    byte = readbytes(STDIN, 1)[1]
+    raw_mode!(false)
 
-    skip_to_end = false
+    if byte == 0x0d
+        return 0x0a
+    elseif byte == 127
+        return 0x08
+    else
+        return byte
+    end
+end
+
+KEY_CFA = defPrimWord("KEY", () -> begin
+    pushPS(Int(getKey()))
+    return NEXT
+end)
+
+function getLineFromSTDIN()
+    line = ""
     while true
+        key = Char(getKey())
 
-        callPrim(mem[KEY])
-        c = Char(popPS())
+        if key == '\n'
+            print(" ")
+            return ASCIIString(line)
 
-        if c == '\\'
-            skip_to_end = true
-            continue
-        end
+        elseif key == '\x04'
+            if isempty(line)
+                return string("\x04")
+            end
 
-        if skip_to_end
-            if c == '\n' || c == eof_char
-                skip_to_end = false
+        elseif key == '\b'
+            if !isempty(line)
+                line = line[1:length(line)-1]
+                print("\b \b")
             end
-            continue
-        end
 
-        if c == ' ' || c == '\t'
-            continue
-        end
+        elseif key == '\e'
+            # Strip ANSI escape sequence
+            nextKey = Char(getKey())
+            if nextKey == '['
+                while true
+                    nextKey = Char(getKey())
+                    if nextKey >= '@' || nextKey <= '~'
+                        break
+                    end
+                end
+            end
 
-        break
+        else
+            print(key)
+            line = string(line, key)
+        end
     end
+end
 
-    wordAddr = mem[HERE]
-    offset = 0
-
-    if c == '\n' || c == eof_char
-        # Treat newline as a special word
+SPAN, SPAN_CFA = defNewVar("SPAN", 0)
+EXPECT_CFA = defPrimWord("EXPECT", () -> begin
+    maxLen = popPS()
+    addr = popPS()
 
-        mem[wordAddr + offset] = Int64(c)
-        pushPS(wordAddr)
-        pushPS(1)
-        return NEXT
+    if currentSource() == STDIN
+        line = getLineFromSTDIN()
+    else
+        if !eof(currentSource())
+            line = chomp(readline(currentSource()))
+        else
+            line = "\x04" # eof
+        end
     end
 
-    while true
-        mem[wordAddr + offset] = Int64(c)
-        offset += 1
+    mem[SPAN] = min(length(line), maxLen)
+    putString(line[1:mem[SPAN]], addr)
 
-        callPrim(mem[KEY])
-        c = Char(popPS())
+    return NEXT
+end)
 
-        if c == ' ' || c == '\t' || c == '\n' || c == eof_char
-            # Rewind KEY
-            mem[TOIN] -= 1
-            break
-        end
-    end
+BASE, BASE_CFA = defNewVar("BASE", 10)
+NUMBER_CFA = defPrimWord("NUMBER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
 
-    wordLen = offset
+    s = getString(wordAddr, wordLen)
 
-    pushPS(wordAddr)
-    pushPS(wordLen)
+    pushPS(parse(Int64, s, mem[BASE]))
 
     return NEXT
 end)
 
-NUMBER = defPrimWord("NUMBER", () -> begin
+# Dictionary searches
 
-    wordLen = popPS()
-    wordAddr = popPS()
+TOCFA_CFA = defPrimWord(">CFA", () -> begin
 
-    s = getString(wordAddr, wordLen)
+    addr = popPS()
+    lenAndFlags = mem[addr+1]
+    len = lenAndFlags & F_LENMASK
 
-    try
-        pushPS(parse(Int64, s, mem[BASE]))
-        pushPS(0)
-    catch
-        pushPS(1) # Error indication
-    end
+    pushPS(addr + 2 + len)
 
     return NEXT
 end)
 
-# Dictionary searches
+TOBODY_CFA = defWord(">BODY", [INCR_CFA, EXIT_CFA])
 
-FIND = defPrimWord("FIND", () -> begin
+FIND_CFA = defPrimWord("FIND", () -> begin
 
-    wordLen = popPS()
-    wordAddr = popPS()
+    countedAddr = popPS()
+    wordAddr = countedAddr + 1
+    wordLen = mem[countedAddr]
     word = lowercase(getString(wordAddr, wordLen))
 
     latest = LATEST
+    lenAndFlags = 0
     
     i = 0
     while (latest = mem[latest]) > 0
@@ -694,211 +731,270 @@ FIND = defPrimWord("FIND", () -> begin
         end
     end
 
-    pushPS(latest)
+    if latest > 0
+        pushPS(latest)
+        callPrim(mem[TOCFA_CFA])
+        if (lenAndFlags & F_IMMED) == F_IMMED
+            pushPS(1)
+        else
+            pushPS(-1)
+        end
+    else
+        pushPS(countedAddr)
+        pushPS(0)
+    end
 
     return NEXT
 end)
 
-TOCFA = defPrimWord(">CFA", () -> begin
-
-    addr = popPS()
-    lenAndFlags = mem[addr+1]
-    len = lenAndFlags & F_LENMASK
 
-    pushPS(addr + 2 + len)
+# Branching
 
+BRANCH_CFA = defPrimWord("BRANCH", () -> begin
+    reg.IP += mem[reg.IP]
     return NEXT
 end)
 
-TODFA = defWord(">DFA", [TOCFA, INCR, EXIT])
-
-# Compilation
+ZBRANCH_CFA = defPrimWord("0BRANCH", () -> begin
+    if (popPS() == 0)
+        reg.IP += mem[reg.IP]
+    else
+        reg.IP += 1
+    end
 
-CREATE = defPrimWord("CREATE", () -> begin
+    return NEXT
+end)
 
-    wordLen = popPS()
-    wordAddr = popPS()
-    word = getString(wordAddr, wordLen)
+# Strings
 
-    createHeader(word, 0)
+LITSTRING_CFA = defPrimWord("LITSTRING", () -> begin
+    len = mem[reg.IP]
+    reg.IP += 1
+    pushPS(reg.IP)
+    pushPS(len)
+    reg.IP += len
 
     return NEXT
 end)
 
-COMMA = defPrimWord(",", () -> begin
-    mem[mem[HERE]] = popPS()
-    mem[HERE] += 1
-
+TYPE_CFA = defPrimWord("TYPE", () -> begin
+    len = popPS()
+    addr = popPS()
+    str = getString(addr, len)
+    print(str)
     return NEXT
 end)
 
-LBRAC = defPrimWord("[", () -> begin
-    mem[STATE] = 0
-    return NEXT
-end, flags=F_IMMED)
+# Interpreter/Compiler-specific I/O
 
-RBRAC = defPrimWord("]", () -> begin
-    mem[STATE] = 1
-    return NEXT
-end, flags=F_IMMED)
+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])
+
+WORD_CFA = defPrimWord("WORD", () -> begin
+    delim = popPS()
+
+    # Chew up initial occurrences of delim
+    while (mem[TOIN]<mem[NUMTIB] && mem[TIB+mem[TOIN]] == delim)
+        mem[TOIN] += 1
+    end
+
+    countAddr = mem[H]
+    addr = mem[H]+1
+
+    # Start reading in word
+    count = 0
+    while (mem[TOIN]<mem[NUMTIB])
+        mem[addr] = mem[TIB+mem[TOIN]]
+        mem[TOIN] += 1
+
+        if (mem[addr] == delim)
+            break
+        end
+
+        count += 1
+        addr += 1
+    end
+
+    # Record count
+    mem[countAddr] = count
+    pushPS(countAddr)
 
-HIDDEN = defPrimWord("HIDDEN", () -> begin
-    addr = popPS() + 1
-    mem[addr] = mem[addr] $ F_HIDDEN
     return NEXT
 end)
 
-HIDE = defWord("HIDE",
-    [WORD,
-    FIND,
-    HIDDEN,
-    EXIT])
+# Compilation
 
-COLON = defWord(":",
-    [WORD,
-    CREATE,
-    LIT, DOCOL, COMMA,
-    LATEST_CFA, FETCH, HIDDEN,
-    RBRAC,
-    EXIT])
+STATE, STATE_CFA = defNewVar("STATE", 0)
 
-SEMICOLON = defWord(";",
-    [LIT, EXIT, COMMA,
-    LATEST_CFA, FETCH, HIDDEN,
-    LBRAC,
-    EXIT], flags=F_IMMED)
+COMMA_CFA = defPrimWord(",", () -> begin
+    mem[mem[H]] = popPS()
+    mem[H] += 1
 
-IMMEDIATE = defPrimWord("IMMEDIATE", () -> begin
-    lenAndFlagsAddr = mem[LATEST] + 1
-    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
     return NEXT
-end, flags=F_IMMED)
+end)
 
-TICK = defWord("'", [WORD, FIND, TOCFA, EXIT])
+HERE_CFA = defWord("HERE",
+    [H_CFA, FETCH_CFA, EXIT_CFA])
 
-# Branching
+HEADER_CFA = defPrimWord("HEADER", () -> begin
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
+    word = getString(wordAddr, wordLen)
+
+    createHeader(word, 0)
 
-BRANCH = defPrimWord("BRANCH", () -> begin
-    reg.IP += mem[reg.IP]
     return NEXT
 end)
 
-ZBRANCH = defPrimWord("0BRANCH", () -> begin
-    if (popPS() == 0)
-        reg.IP += mem[reg.IP]
-    else
-        reg.IP += 1
-    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)
+end, name="DODOES")
 
-# Strings
+DOES_HELPER_CFA = defPrimWord("(DOES>)", () -> begin
 
-LITSTRING = defPrimWord("LITSTRING", () -> begin
-    len = mem[reg.IP]
-    reg.IP += 1
-    pushPS(reg.IP)
-    pushPS(len)
-    reg.IP += len
+    pushPS(mem[LATEST])
+    callPrim(mem[TOCFA_CFA])
+    cfa = popPS()
+
+    runtimeAddr = popPS()
+
+    mem[cfa] = defPrim(eval(:(() -> begin
+        pushPS($(runtimeAddr))
+        return DODOES
+    end)), name="doesPrim")
 
     return NEXT
-end)
+end, flags=F_IMMED)
 
-TELL = defPrimWord("TELL", () -> begin
-    len = popPS()
-    addr = popPS()
-    str = getString(addr, len)
-    print(str)
+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)
+end, flags=F_IMMED)
 
-# Outer interpreter
+RBRAC_CFA = defPrimWord("]", () -> begin
+    mem[STATE] = 1
+    return NEXT
+end, flags=F_IMMED)
 
-EXECUTE = defPrimWord("EXECUTE", () -> begin
-    reg.W = popPS()
-    return mem[reg.W]
+HIDDEN_CFA = defPrimWord("HIDDEN", () -> begin
+    lenAndFlagsAddr = mem[LATEST] + 1
+    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_HIDDEN
+    return NEXT
 end)
 
-INTERPRET = defPrimWord("INTERPRET", () -> begin
+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[LATEST] + 1
+    mem[lenAndFlagsAddr] = mem[lenAndFlagsAddr] $ F_IMMED
+    return NEXT
+end, flags=F_IMMED)
 
-    callPrim(mem[WORD])
+# Outer Interpreter
 
-    wordName = getString(mem[reg.PSP-1], mem[reg.PSP])
-    #println("... ", replace(wordName, "\n", "\\n"), " ...")
+EXECUTE_CFA = defPrimWord("EXECUTE", () -> begin
+    reg.W = popPS()
+    return mem[reg.W]
+end)
 
-    callPrim(mem[TWODUP])
-    callPrim(mem[FIND])
+INTERPRET_CFA = defWord("INTERPRET",
+    [LIT_CFA, 32, WORD_CFA, # Read next space-delimited word
 
-    wordAddr = mem[reg.PSP]
+    DUP_CFA, FETCH_CFA, ZE_CFA, ZBRANCH_CFA, 3,
+        DROP_CFA, EXIT_CFA, # Exit if TIB is exhausted
 
-    if wordAddr>0
-        # Word in dictionary
+    STATE_CFA, FETCH_CFA, ZBRANCH_CFA, 24,
+        # Compiling
+        FIND_CFA, QDUP_CFA, ZBRANCH_CFA, 13,
 
-        isImmediate = (mem[wordAddr+1] & F_IMMED) != 0
-        callPrim(mem[TOCFA])
+            # Found word. 
+            LIT_CFA, -1, EQ_CFA, INVERT_CFA, ZBRANCH_CFA, 4,
 
-        callPrim(mem[ROT]) # get rid of extra copy of word string details
-        popPS()
-        popPS()
+                # Immediate: Execute!
+                EXECUTE_CFA, BRANCH_CFA, -26,
 
-        if mem[STATE] == 0 || isImmediate
-            # Execute!
-            #println("Executing CFA at $(mem[reg.PSP])")
-            return callPrim(mem[EXECUTE])
-        else
-            # Append CFA to dictionary
-            callPrim(mem[COMMA])
-        end
-    else
-        # Not in dictionary, assume number
+                # Not immediate: Compile!
+                COMMA_CFA, BRANCH_CFA, -29,
 
-        popPS()
+            # 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,
 
-        callPrim(mem[NUMBER])
+            # Found word. Execute!
+            DROP_CFA, EXECUTE_CFA, BRANCH_CFA, -44,
 
-        if popPS() != 0
-            println("Parse error at word: '$wordName'")
-            return NEXT
-        end
+            # No word found, parse number and leave on stack
+            NUMBER_CFA, BRANCH_CFA, -47,
+    EXIT_CFA])
 
-        if mem[STATE] == 0
-            # Number already on stack!
-        else
-            # Append literal to dictionary
-            pushPS(LIT)
-            callPrim(mem[COMMA])
-            callPrim(mem[COMMA])
-        end
+PROMPT_CFA = defPrimWord("PROMPT", () -> begin
+    if (mem[STATE] == 0 && currentSource() == STDIN)
+        println(" ok")
     end
 
     return NEXT
 end)
 
-QUIT = defWord("QUIT",
-    [RSP0_CFA, RSPSTORE,
-    INTERPRET,
-    BRANCH,-2])
+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",
+    [PSP0_CFA, PSPSTORE_CFA, QUIT_CFA])
 
-BYE = defPrimWord("BYE", () -> begin
+BYE_CFA = defPrimWord("BYE", () -> begin
+    println("\nBye!")
     return 0
 end)
 
-NL = defPrimWord("\n", () -> begin
-    if mem[STATE] == 0 && reg.source == STDIN
-        println(" ok")
-    end
-    return NEXT
-end, flags=F_IMMED)
-
-INCLUDE = defPrimWord("INCLUDE", () -> begin
+# File I/O
 
-    callPrim(mem[WORD])
-    wordLen = popPS()
-    wordAddr = popPS()
+INCLUDE_CFA = defPrimWord("INCLUDE", () -> begin
+    pushPS(32)
+    callPrim(mem[WORD_CFA])
+    wordAddr = popPS()+1
+    wordLen = mem[wordAddr-1]
     word = getString(wordAddr, wordLen)
 
-    reg.source = open(word, "r")
+    push!(sources, open(word, "r"))
 
     # Clear input buffer
     mem[NUMTIB] = 0
@@ -906,43 +1002,70 @@ INCLUDE = defPrimWord("INCLUDE", () -> begin
     return NEXT
 end)
 
-EOF_WORD = defPrimWord("\x04", () -> begin
-    if reg.source == STDIN
-        return 0
-    else
-        close(reg.source)
-        reg.source = STDIN
-        return NEXT
-    end
-end, flags=F_IMMED)
 
-# Odds and Ends
+#### VM loop ####
 
-CHAR = defPrimWord("CHAR", () -> begin
-    callPrim(mem[WORD])
-    wordLen = popPS()
-    wordAddr = popPS()
-    word = getString(wordAddr, wordLen)
-    pushPS(Int64(word[1]))
+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
 
-    return NEXT
-end)
+function run(;initialize=true)
+    # Begin with STDIN as source
+    push!(sources, STDIN)
+
+    global initialized, initFileName
+    if !initialized && initialize
+        if initFileName != nothing
+            print("Including definitions from $initFileName...")
+            push!(sources, open(initFileName, "r"))
+            initialized = true
+        else
+            println("No library file found. Only primitive words available.")
+        end
+    end
 
-#### VM loop ####
-function run()
     # 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 = NEXT
-    while (jmp = callPrim(jmp)) != 0
-        #println("Evaluating prim $jmp [$(primNames[-jmp])]")
+    while jmp != 0
+        try
+            #println("Entering prim $(getPrimName(jmp))")
+            jmp = callPrim(jmp)
+
+        catch ex
+            showerror(STDOUT, ex)
+            println()
+
+            while !isempty(sources) && currentSource() != STDIN
+                close(pop!(sources))
+            end
+
+            # 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)
 
@@ -977,11 +1100,11 @@ function dump(startAddr::Int64; count::Int64 = 100, cellsPerLine::Int64 = 10)
 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()
@@ -991,11 +1114,11 @@ 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()
@@ -1004,4 +1127,14 @@ function printRS()
     end
 end
 
+DUMP = defPrimWord("DUMP", () -> begin
+    count = popPS()
+    addr = popPS()
+
+    println()
+    dump(addr, count=count)
+
+    return NEXT
+end)
+
 end