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24 HOURS LATERPhillip Trelford, @ptrelfordBuild Stuff, Lithuania, 2014
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THIS TALK IS *NOT*
About how to write a compiler the hard way
All theory
For the faint of heart
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THIS TALK *IS* ABOUT
Abstract Syntax Trees
Parsing
Domain Specific Languages
Interpreters
Code Generation
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LANGUAGE FAMILIES
Lisp
C
ML
BASIC
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LANGUAGE DESIGN (CONSIDERED OPTIONAL)
Adhoc• PHP• JavaScript• Scala
Copy&Delete• Java• J• Go
Copy&Add• C#• F#• Haskell
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TO THE TURTLES CODE
Phillip Trelford, @ptrelfordBuild Stuff, Lithuania, 2014
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TURTLE LANGUAGE
repeat 10
[right 36 repeat 5
[forward 54 right 72]]
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TURTLE AST
module AST
type arg = int
type command =
| Forward of arg
| Turn of arg
| Repeat of arg * command list
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TWO GIRLS (5 & 7YRS) + TURTLE
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SMALL BASIC SAMPLE
Sub Init
gw = 598
gh = 428
GraphicsWindow.BackgroundColor = "DodgerBlue"
GraphicsWindow.Width = gw
GraphicsWindow.Height = gh
color = "1=Orange;2=Cyan;3=Lime;"
size = "1=20;2=16;3=12;"
passed = 0
cd = "False" ' collision detected
EndSub
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SMALL BASIC AST
/// Small Basic expressiontype expr = | Literal of value | Identifier of identifier | GetAt of location | Func of invoke | Neg of expr | Arithmetic of expr * arithmetic * expr | Comparison of expr * comparison * expr | Logical of expr * logical * expr
/// Small Basic instruction type instruction = | Assign of assign | SetAt of location * expr | PropertySet of string * string * expr
| Action of invoke | For of assign * expr * expr | EndFor | If of expr | ElseIf of expr | Else | EndIf | While of expr | EndWhile | Sub of identifier * string list | EndSub | Label of label | Goto of label
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C# COMPILER IN 24 DAYS
Oh Yes! Neil Danson (aka The Do)
Now, I didn’t do any compiler theory in uni, I’ve never written a compiler before and I’ve only ever looked at Reflection Emit in anger. But despite these limitations I have a fairlycapable C# 0.5 compiler (in that it is a subset of the C# 1 compiler). Which means you can do it too – it took me less than a month.
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RESOURCESPhillip Trelford, @ptrelfordBuild Stuff, Lithuania, 2014
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F# KOANS
[<Koan>]let SquareEvenNumbersWithPipelineOperator() =(* In F#, you can use the pipeline operator to get the benefit of the parens style with the readability of the statement style. *)
let result = [0..5] |> List.filter isEven |> List.map square AssertEquality result __
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TRYFSHARP.ORG
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F# BOOKS
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QUESTIONS?
Twitter: @ptrelford
Blog: http://trelford.com/blog
Turtle: http://fssnip.net/nN