# # comment
# - slide separator
# . pause
# ! shell command
Reducing Interpreter Overhead

Eastbourne '14
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performance
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a←36 99 20  5 63 50 26 10 50 64
b←90 68 98 66 72 27 74 44  1 46
c←62 48  9 90 81 22 79 60 70 98
a+b×c
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a←36
b←90
c←62
((-b)(+,-)((b*2)-4×a×c)*.5)÷2×a
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a compiler
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lexer    → tokens
.
parser   → tree
.
compiler → tree'
.
codegen  → instructions
.
exec
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lexer    → tokens        ⎫
parser   → tree          ⎬ compile time
compiler → tree'         ⎪
codegen  → instructions  ⎭
exec                     } run time
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lexer    → tokens        } "fix" time  
parser   →               ⎫
         →               ⎪
         →               ⎬ run time
exec                     ⎭
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((-b)(+,-)((b*2)-4×a×c)*.5)÷2×a
                              ^
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((-b)(+,-)((b*2)-4×a×c)*.5)÷2×a
                             ^
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((-b)(+,-)((b*2)-4×a×c)*.5)÷2×a
                            ^
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the compiler
.
    v14.0
.

Jay's compiler
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# gthumb must be configured to "fit to window" and not to "change slides automatically"
!gthumb -s jay/jay.jpg
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mean←{
  a←+⌿⍵
  b←≢⍵
  a÷b
}
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                    apply
mean←{           ╭────┼────╮
  a←+⌿⍵        apply  ÷  apply
  b←≢⍵         ╭─┴─╮     ╭─┴─╮
  a÷b         derv ⍵     ≢   ⍵
}             ╭┴╮
              + ⌿
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                    apply
mean←{           ╭────┼────╮
  a←+⌿⍵        apply  ÷  apply
  b←≢⍵         ╭─┴─╮     ╭─┴─╮
  a÷b         derv │     ≢   │
}             ╭┴╮  ╰────┬────╯
              + ⌿       ⍵
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0000: 00000005 // version 5
0001: 00000000 // localised system variables: none
0002: 00000201 // 2 slots
0003: 00002004 rel Larg
0004: 000071C4 cpy PFUNCTION, rawlst[3]
0005: 00000545 cpy slot[0], Rarg
0006: 00000003 eval
0007: 00003B11 tokoff 003B
0008: 00000444 mov Rarg, slot[0]
0009: 00002465 mov slot[1], Rslt
000A: 00001F03 eval 0x1F // ≢
000B: 00004511 tokoff 0045
000C: 00002424 mov Larg, slot[1]
000D: 00006044 mov Rarg, Rslt
000E: 00000503 eval 0x05 // ÷
000F: 00004E11 tokoff 004E
0010: 00000002 ret
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How do I use it?
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1(400⌶)'f'  ⍝ compiled?
.
2(400⌶)'f'  ⍝ compile
.
3(400⌶)'f'  ⍝ uncompile
.
4(400⌶)'f'  ⍝ dump bytecode
.

400⌶1       ⍝ compile new functions
400⌶1+2     ⍝ ... and operators
400⌶1+2+4   ⍝ ... and in-line dfns
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      f←{1+⍵}
.
      1(400⌶)'f'  ⍝ compiled?
.
0
.
      2(400⌶)'f'  ⍝ compile
.
      1(400⌶)'f'  ⍝ compiled?
.
1
.
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a b c

.
1 2 3
.
1 + 3
.
- ÷ 3
.
+ / 3
.
+ . ×
.
+ , ×
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!gthumb -s ducks1/ducks1.jpg
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     We must know
the kind of every name
    ahead of time!

array
function
monadic operator
dyadic operator
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f←{a+2}
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system functions

⎕ex ⎕nl ⎕fx ⎕na ⎕ns...
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+/
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f⍨
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 f⍨⍵ ←→ ⍵f⍵
.
⍺f⍨⍵ ←→ ⍵f⍺
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()
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[]
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⍝
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      ⎕cr'f'          ⎕cr'f'
r←f x           r←f x
r←x+1           r←x+1
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{1 ⋄ 2}
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{a←1 ⋄ 2}
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a ←⊂0 1 0
a,←⊂1 0 0
a,←⊂1 1 1
a←↑a
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a←⍉⍪0 1 0
a⍪← 1 0 0
a⍪← 1 1 1
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{
  ⎕io←0
  (a b c)←⍳3                    
  ...
}
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{
  ⎕io←0
  (a b c)←⍳3   ⍝ a←0 ⋄ b←1 ⋄ c←2
  ...
}
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○1
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tail call optimisation

{⍵=0:0 ⋄ ⍵+∇⍵-1} ⍝ no
.

{⍵=0:⍺ ⋄ (⍺+⍵)∇⍵-1} ⍝ yes
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(a/b)←c
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a[i]←b
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a+←b
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namespaces

{⍵.f ⍵.x}
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{⍺+.×⍵}
.
{⍺∘.×⍵}
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⍺←1
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⍺←⊢
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f←{
  ⍺←⊢
  ⍺g⍵
}
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{x:y ⋄ z}
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{... ⍺⍺ ...}
.
{... ⍵⍵ ...}
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⍎
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{a←1 ⋄ ⍎'a←2'}
.
{a←1 ⋄ ⍎'⎕ex''a'' ⋄ a←+'}
.
{f←⍎'+'}
.
{a←⍎'→' ⋄ 1}
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!gthumb -s ducks2/ducks2.jpg
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⍺(f g h)⍵ ←→ (⍺f⍵)g(⍺h⍵)
⍺(A g h)⍵ ←→   A  g(⍺h⍵)
⍺(  g h)⍵ ←→      g(⍺h⍵)
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idiom recognition

0=⍴⍴⍵     ,/⍵     ⊃⌽⍵
   ↓⍉↑⍵     {⍵[⍋⍵]}
  {(+/∨\' '≠⌽⍵)↑¨↓⍵}
        ...
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∇r←x tradfn y;l0;l1;l2
  ...
∇
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control structures

:If
:For
:While
 ...
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∇tradfn
  label: ...
  →label
∇
-
 ...
.
test with
2(400⌶)'f'
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future

.
loop fusion: a+b×c
.
control structures
.
non-local names
.
common subexpressions: {(1-⍵*2)÷1+⍵*2}
.
array morphology inference: {1+≢⍵}
.
assumptions
.
compilability indicator in the GUI
.
 ...
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thank you

'jay' 'nick' ,¨⊂ '@dyalog.com'
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questions