2015.01.06 f sharp_intro_milan_kubicek
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This document discusses parsing F# code with PetitParser. It focuses on indentation-sensitive features of F#, including the off-side rule where code must be indented at the same level or further than the previous line. The document presents some F# code examples and discusses challenges in building a PetitParser grammar to parse the F# syntax.
2015.01.06 f sharp_intro_milan_kubicek
- 1. Parsing F# with PetitParser F# indentation sensitive lightweight syntax ? ? Milan Kubicek ? SCG Seminar ? 06.01.2015
- 3. 3 ..some nicer F# code Output:? 1: 1 2: 1 3: 2 4: 3 5: 5 6: 8 7: 13 8: 21 9: 34 10: 55
- 4. 4 indentation? as secondary notation indentation? as formal notation
- 5. indentation? in programming secondary notation ? / syntactic sugar define structure F# Python Haskell ¡°curly bracket programming languages¡± 5 ¡°indentation sensitive? programming languages¡±
- 6. 6 off-side rule off-side on-side off-side line valid pass! foul pass!
- 10. 10 off-side rule exceptions off-side on-side off-side line
- 11. 11 off-side rule exceptions ¡°then-&else-body on-side aligned¡± ¡°then-body aligned¡± ¡°else-body aligned¡±
- 12. 12 challanges F# language definition (Petit)Parsing knowledge mini F# PetitParser grammar (using PetitIndent)
- 13. 13 F# lightweight syntax indentation as primary notation: ..code position changes semantics! off-side on-side off-side line aligned
- 14. 14 questions?
- 15. 15
- 16. ¨C http://en.wikipedia.org/wiki/Secondary_notation 05.01.2015 ¡°¡An example of secondary notation is in computer programming, where code is often displayed with positioning, indentation, color and symmetry. This does not affect the behaviour of the program, but it makes it easier to read and understand the code¡¡± 16 secondary notation
- 17. ¨CPeter J. Landin, ¡°The Next 700 Programming Languages¡± ¡°Any non-whitespace token to the left of the first such token on the previous line is taken to be the start of a new declaration.¡± Off-side rule 17