parsing - Writing correct LL(1) grammars? -


i'm trying write (very) small interpreter/compiler programming language. have set syntax language, , need write down grammar language. intend use ll(1) parser because, after bit of research, seems easiest use.

i new domain, gathered, formalising syntax using bnf or ebnf highly recommended. however, seems not grammars suitable implementation using ll(1) parser. therefore, wondering correct (or recommended) approach writing grammars in ll(1) form.

thank help, charlie.

ps: intend write parser using haskell's parsec library.

edit: also, according sk-logic, parsec can handle infinite lookahead (ll(k) ?) - guess question still stands type of grammar.

i'm not expert on have made similar small project lr(0) parser. general approach recommend:

  1. get arithmetics working. this, make rules , derivations +, -, /, * etc , sure parser produces working abstract syntax tree. test , evaluate tree on different input ensure arithmetic correctly. make things step step. if encounter conflict, resolve first before moving on.

  2. get simper constructs working if-then-else or case expressions working.

  3. going further depends more on language you're writing grammar for.

definetly check out other programming language grammars reference (unfortunately did not find in 1 min full ll grammar language online, lr grammars should useful reference too). example:

ansi c grammar

python grammar

and of course small examples in wikipedia ll grammars wikipedia ll parser have checked out.

i hope find of stuff useful


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