package reparse

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package reparse
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Module Parser.InfixSource

Provides functions to support infix and let syntax operators.

Open the module to use it:

 open Reparse.Parser.Infix
Sourceval (>>=) : 'a t -> ('a -> 'b t) -> 'b t

p >>= f returns a new parser b where,

  • a is the parsed value of p
  • b is f a

Also known as bind operation.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let f a = P.pure (Char.code a) in
  let p = P.char 'h' in
  let p = p >>= f in
  let v = P.parse_string p "hello" in
  v = 104
Sourceval (>|=) : 'a t -> ('a -> 'b) -> 'b t

p >|= f returns a new parser encapsulating value b where,

  • a is the parsed value of p.
  • b is f a.

Also known as map operation.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let f a = Char.code a in
  let p = P.char 'h' in
  let p = p >|= f in
  let v = P.parse_string p "hello" in
  v = 104
Sourceval (<*>) : ('a -> 'b) t -> 'a t -> 'b t

pf <*> q returns a new parser encapsulating value b where

  • pf and q are evaluated sequentially in order as given.
  • f is the parsed value of pf
  • a is the parsed value of q
  • b is f a

Also known as Applicative operation.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let f a = a + 2 in
  let pf = P.pure f in
  let q = P.pure 2 in
  let p = pf <*> q in
  let v = P.parse_string p "hello" in
  v = 4
Sourceval (<$) : 'b -> 'a t -> 'b t

v <$ p replaces the parse value of p with v.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let v = "hello" in
  let p = P.char 'h' in
  let p = v <$ p in
  let v2 = P.parse_string p "hello" in
  v2 = "hello"
Sourceval (<$>) : ('a -> 'b) -> 'a t -> 'b t

f <$> p returns a parser encapsulating value b where,

  • a is the parsed value of p
  • b is f a

This is the infix version of map.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let f a = a ^ " world" in
  let p = P.string "hello" in
  let p = f <$> p in
  let v = P.parse_string p "hello" in
  v = "hello world"
Sourceval (*>) : _ t -> 'a t -> 'a t

p *> q returns a parser encapsulating value a where,

  • p, q are evaluated sequentially in order as given.
  • a is parsed value of q.
  • The parsed value of p is discarded.

Also known as discard left.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let p = P.string "world" in
  let q = P.pure "hello" in
  let p = p *> q in
  let v = P.parse_string p "world" in
  v = "hello"
Sourceval (<*) : 'a t -> _ t -> 'a t

p <* q returns a parser encapsulating value a where,

  • p, q are evaluated sequentially in order as given.
  • a is parsed value of p.
  • The parsed value of q is discarded.

Also know as discard_right.

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let p = P.string "world" in
  let q = P.pure "hello" in
  let p = p <* q in
  let v = P.parse_string p "world" in
  v = "world"
Sourceval (<|>) : 'a t -> 'a t -> 'a t

p <|> q returns a parser encapsulating value a where,

  • p,q are evaluated sequentially in order as given.
  • a is the parsed value of p if p is successful
  • a is the parsed value of q if p is a failure and q is a success.
  • If both - p and q - fails, then the parser fails.

Examples

p fails and q succeeds, therefore we return q's parsed value 'w'

  module P = Reparse.Parser
  open P.Infix

  ;;
  let p = P.char 'h' in
  let q = P.char 'w' in
  let p = p <|> q in
  let v = P.parse_string p "world" in
  v = 'w'

p succeeds therefore we return its parsed value 'h'

  let p = P.char 'h' in
  let q = P.char 'w' in
  let p = p <|> q in
  let v = P.parse_string p "hello" in
  v = 'h'

The parser fails if both p and q fails.

  let p = P.char 'h' in
  let q = P.char 'w' in
  let p = p <|> q in
  let v =
    try
      let _ = P.parse_string p "" in
      false
    with
    | _ -> true
  in
  v = true
Sourceval (<?>) : 'a t -> string -> 'a t

p <?> err_msg parses p to value a and returns a new parser encapsulating a. If p is a failure, then it fails with error message err_msg.

Often used as a last choice in <|>, e.g. a <|> b <|> c <?> "expected a b c".

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let p = P.char 'h' <|> P.char 'w' in
  let err_msg = "[error]" in
  let p = p <?> err_msg in
  let v =
    try
      let _ = P.parse_string p "" in
      false
    with
    | P.Parser { offset = 0; line_number = 0; column_number = 0; msg = "[error]" }
      -> true
    | _ -> false
  in
  v = true
Sourceval (let*) : 'a t -> ('a -> 'b t) -> 'b t

let* is a let syntax binding for (>>=)

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let p =
    let* a = P.pure 5 in
    let total = a + 5 in
    P.pure total
  in
  let v = P.parse_string p "" in
  v = 10
Sourceval (let+) : 'a t -> ('a -> 'b) -> 'b t

let* is a let syntax binding for (>|=)

Examples

  module P = Reparse.Parser
  open P.Infix

  ;;
  let p =
    let+ a = P.pure 5 in
    let total = a + 5 in
    total
  in
  let v = P.parse_string p "" in
  v = 10