wolfpack-parser 0.2.0

The parser of wolfpack. Internal part of wolfpack-lang, not a stable API
Documentation 
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---
source: crates/wolf_parser/tests/parser.rs
expression: result.dump
---
file
  doc! " A bank: ownership in action. `mut` parameters change an account in place, `own` takes it"
  doc! " away, and the compiler rejects `transfer(mut alice, mut alice, 10)` because the two `mut`"
  doc! " arguments overlap (chapter 5, section 7.2)."
  module main
  section types
    (struct Account (field owner String) (field balance Int))
    enum
      BankError
      (variant doc " The amount that is missing." InsufficientFunds (tuple Int))
      (variant InvalidAmount (tuple Int))
  section impl
    impl
      Account
      fn
        open
        (params (own owner String) (deposit Int))
        (-> Account)
        (block (struct Account owner (balance: deposit)))
      fn
        deposit
        (params mut self (amount Int))
        (-> (Result Void BankError))
        block
          (if (<= amount 0) (block (return (call Err (call (. BankError InvalidAmount) amount)))))
          (+= (. self balance) amount)
          (call Ok ())
      fn
        withdraw
        (params mut self (amount Int))
        (-> (Result Void BankError))
        block
          (if (<= amount 0) (block (return (call Err (call (. BankError InvalidAmount) amount)))))
          if
            (> amount (. self balance))
            block
              (return (call Err (call (. BankError InsufficientFunds) (- amount (. self balance)))))
          (-= (. self balance) amount)
          (call Ok ())
      fn
        summary
        (params self)
        (-> String)
        (block (+ (+ (. self owner) ": ") (call (. (. self balance) to_string))))
    impl
      BankError
      (for Error)
      fn
        message
        (params self)
        (-> String)
        block
          match
            self
            =>
              (BankError.InsufficientFunds missing)
              (+ "insufficient funds, missing " (call (. missing to_string)))
            (=> (BankError.InvalidAmount amount) (+ "invalid amount " (call (. amount to_string))))
  section main
    fn
      main
      ()
      (-> (Result Void Error))
      block
        (var alice (call (. Account open) "Alice" 100))
        (var bob (call (. Account open) "Bob" 20))
        (? (call transfer (mut alice) (mut bob) 30))
        (call print (call (. alice summary)))
        (call print (call (. bob summary)))
        match
          (call transfer (mut bob) (mut alice) 500)
          (=> (Ok _) (call print "transfer done"))
          (=> (Err error) (call print (+ "transfer failed: " (call (. error message)))))
        (let final_balance (call close (own bob)))
        (call print (+ "closed Bob's account with " (call (. final_balance to_string))))
        match
          (call (. alice deposit) 0)
          (=> (Ok _) (call print "deposit done"))
          (=> (Err error) (call print (+ "deposit failed: " (call (. error message)))))
        (call print (call (. alice summary)))
        (call Ok ())
  section functions
    fn
      doc " Moves money between two different accounts."
      transfer
      (params (mut from Account) (mut to Account) (amount Int))
      (-> (Result Void BankError))
      (block (? (call (. from withdraw) amount)) (? (call (. to deposit) amount)) (call Ok ()))
    fn
      doc " Closes the account and returns its final balance. The caller can no longer use it."
      close
      (params (own account Account))
      (-> Int)
      (block (. account balance))
  section tests
    test
      "transfer moves money"
      block
        (var a (call (. Account open) "A" 10))
        (var b (call (. Account open) "B" 0))
        (call assert (== (call transfer (mut a) (mut b) 10) (call Ok ())))
        (call assert (== (. a balance) 0))
        (call assert (== (. b balance) 10))
    test
      "a failed withdrawal changes nothing"
      block
        (var a (call (. Account open) "A" 5))
        call
          assert
          (== (call (. a withdraw) 8) (call Err (call (. BankError InsufficientFunds) 3)))
        (call assert (== (. a balance) 5))
    test
      "closing returns the balance"
      (block (let a (call (. Account open) "A" 42)) (call assert (== (call close (own a)) 42)))