Readme.md

@@ -12,7 +12,7 @@ Use the [Nimble][3] package manager to add `questionable` to an existing
 project. Add the following to its .nimble file:
 
 ```nim
-requires "questionable >= 0.10.15 & < 0.11.0"
+requires "questionable >= 0.10.12 & < 0.11.0"
 ```
 
 If you want to make use of Result types, then you also have to add either the
@@ -151,7 +151,7 @@ have to explicitly import the `questionable/results` module:
 import questionable/results
 ```
 
-You can use `?!` to make a Result type. These Result types either hold a value or
+You can use `?!` make a Result type. These Result types either hold a value or
 an error. For example the type `?!int` is short for `Result[int, ref
 CatchableError]`.
 
@@ -226,7 +226,6 @@ Any Result can be converted to an Option:
 
 ```nim
 let converted = works().option  # equals @[1, 1, 2, 2, 2].some
-let errOption = fails().errorOption # option that is set when the Result holds an error
 ```
 
 [1]: https://nim-lang.org/docs/options.html

questionable.nimble

@@ -1,4 +1,4 @@
-version = "0.10.15"
+version = "0.10.12"
 author = "Questionable Authors"
 description = "Elegant optional types"
 license = "MIT"

questionable/indexing.nim

@@ -1,24 +1,16 @@
 import std/macros
-import std/options
 
-proc safeGet[T](expression: seq[T] | openArray[T], index: int): Option[T] =
-  if index >= expression.low and index <= expression.high:
-    expression[index].some
-  else:
-    T.none
-
-proc safeGet(expression: string, index: int): Option[char] =
-  if index >= expression.low and index <= expression.high:
-    expression[index].some
-  else:
-    char.none
-
-macro `.?`*(expression: seq | string | openArray, brackets: untyped{nkBracket}): untyped =
-    # chain is of shape: (seq or string or openArray).?[index]
-    let index = brackets[0]
-    quote do:
-      block:
-        safeGet(`expression`, `index`)
+macro `.?`*(expression: seq | string, brackets: untyped{nkBracket}): untyped =
+  # chain is of shape: (seq or string).?[index]
+  let index = brackets[0]
+  quote do:
+    block:
+      type T = typeof(`expression`[`index`])
+      let evaluated = `expression`
+      if `index` < evaluated.len:
+        evaluated[`index`].some
+      else:
+        T.none
 
 macro `.?`*(expression: typed, brackets: untyped{nkBracket}): untyped =
   # chain is of shape: expression.?[index]

questionable/private/bareexcept.nim

@@ -1,6 +0,0 @@
-template ignoreBareExceptWarning*(body) =
-  when defined(nimHasWarnBareExcept):
-    {.push warning[BareExcept]:off warning[UnreachableCode]:off.}
-  body
-  when defined(nimHasWarnBareExcept):
-    {.pop.}

questionable/private/binderror.nim

@@ -1,54 +1,24 @@
 import std/options
-import std/macros
 
-# A stack of names of error variables. Keeps track of the error variables that
-# are given to captureBindError().
-var errorVariableNames {.global, compileTime.}: seq[string]
+var captures {.global, compileTime.}: int
+var errorVariable {.threadvar.}: ptr ref CatchableError
 
-macro captureBindError*(error: var ref CatchableError, expression): auto =
-  ## Ensures that an error is assigned to the error variable when a binding (=?)
-  ## fails inside the expression.
+template captureBindError*(error: var ref CatchableError, expression): auto =
+  let previousErrorVariable = errorVariable
+  errorVariable = addr error
 
-  # name of the error variable as a string literal
-  let errorVariableName = newLit($error)
+  static: inc captures
+  let evaluated = expression
+  static: dec captures
 
-  let evaluated = genSym(nskLet, "evaluated")
-  quote do:
-    # add error variable to the top of the stack
-    static: errorVariableNames.add(`errorVariableName`)
-    # evaluate the expression
-    let `evaluated` = `expression`
-    # pop error variable from the stack
-    static: discard errorVariableNames.pop()
-    # return the evaluated result
-    `evaluated`
+  errorVariable = previousErrorVariable
 
-func unsafeCatchableError[T](_: Option[T]): ref CatchableError =
+  evaluated
+
+func error[T](option: Option[T]): ref CatchableError =
   newException(ValueError, "Option is set to `none`")
 
-func unsafeCatchableError[T](_: ref T): ref CatchableError =
-  newException(ValueError, "ref is nil")
-
-func unsafeCatchableError[T](_: ptr T): ref CatchableError =
-  newException(ValueError, "ptr is nil")
-
-func unsafeCatchableError[Proc: proc | iterator](_: Proc): ref CatchableError =
-  newException(ValueError, "proc or iterator is nil")
-
-macro bindFailed*(expression: typed) =
-  ## Called when a binding (=?) fails.
-  ## Assigns an error to the error variable (specified in captureBindError())
-  ## when appropriate.
-
-  # The `expression` parameter is typed to ensure that the compiler does not
-  # expand bindFailed() before it expands invocations of captureBindError().
-
-  # check that we have an error variable on the stack
-  if errorVariableNames.len > 0:
-    # create an identifier that references the current error variable
-    let errorVariable = ident errorVariableNames[^1]
-    return quote do:
-      # check that the error variable is in scope
-      when compiles(`errorVariable`):
-        # assign bind error to error variable
-        `errorVariable` = `expression`.unsafeCatchableError
+template bindFailed*(expression) =
+  when captures > 0:
+    mixin error
+    errorVariable[] = expression.error

questionable/results.nim

@@ -7,7 +7,6 @@ import ./indexing
 import ./operators
 import ./without
 import ./withoutresult
-import ./private/bareexcept
 
 include ./private/errorban
 
@@ -110,31 +109,18 @@ proc option*[T,E](value: Result[T,E]): ?T =
   ## Converts a Result into an Option.
 
   if value.isOk:
-    ignoreBareExceptWarning:
-      try: # workaround for erroneous exception tracking when T is a closure
-        return value.unsafeGet.some
-      except Exception as exception:
-        raise newException(Defect, exception.msg, exception)
+    try: # workaround for erroneous exception tracking when T is a closure
+      value.unsafeGet.some
+    except Exception as exception:
+      raise newException(Defect, exception.msg, exception)
   else:
-    return T.none
+    T.none
 
 template toOption*[T, E](value: Result[T, E]): ?T =
   ## Converts a Result into an Option.
 
   value.option
 
-proc unsafeCatchableError*[T, E](value: Result[T, E]): ref CatchableError =
-  ## Returns the error from the Result, converted to `ref CatchableError` if
-  ## necessary. Behaviour is undefined when the result holds a value instead of
-  ## an error.
-  when E is ref CatchableError:
-    value.unsafeError
-  else:
-    when compiles($value.unsafeError):
-      newException(ResultFailure, $value.unsafeError)
-    else:
-      newException(ResultFailure, "Result is an error")
-
 proc errorOption*[T, E](value: Result[T, E]): ?E =
   ## Returns an Option that contains the error from the Result, if it has one.
 

questionable/withoutresult.nim

@@ -34,7 +34,7 @@ macro without*(condition, errorname, body: untyped): untyped =
   let body = body.undoSymbolResolution(errorIdent)
 
   quote do:
-    var error {.gensym.}: ref CatchableError
+    var error: ref CatchableError
 
     without captureBindError(error, `condition`):
       template `errorIdent`: ref CatchableError = error

testmodules/options/test.nim

@@ -337,28 +337,13 @@ suite "optionals":
 
   test ".?[] can be used for indexing strings without raising IndexDefect":
     let str = "a"
-    check str.?[0] == 'a'.some
+    check str.?[0] == 'a'.some 
     check str.?[1] == char.none
-    check str.?[-1] == char.none
 
   test ".?[] can be used for indexing sequences without raising IndexDefect":
     let sequence = @[1]
     check sequence.?[0] == 1.some
     check sequence.?[1] == int.none
-    check sequence.?[-1] == int.none
-
-  test ".?[] can be used for indexing openArrays without raising IndexDefect":
-    proc checkOpenArray(oa: openArray[int]): void =
-      check oa.?[0] == 1.some
-      check oa.?[1] == int.none
-      check oa.?[-1] == int.none
-
-    checkOpenArray(@[1])
-
-  test ".?[] evaluates openArray expression only once":
-    var count = 0
-    discard (inc count; @[1].toOpenArray(0, 0)).?[0]
-    check count == 1
 
   test ".?[] can be followed by calls, operators and indexing":
     let table = @{"a": @[41, 42]}.toTable

testmodules/results/test.nim

@@ -326,48 +326,6 @@ suite "result":
     test1()
     test2()
 
-  test "without statement with error handles references as well":
-    proc test =
-      var x: ref int = nil
-      without a =? x, error:
-        check error.msg == "ref is nil"
-        return
-      fail
-
-    test()
-
-  test "without statement with error handles pointers as well":
-    proc test =
-      var x: ptr int = nil
-      without a =? x, error:
-        check error.msg == "ptr is nil"
-        return
-      fail
-
-    test()
-
-  test "without statement with error handles closures as well":
-    proc test =
-      var x = proc = discard
-      x = nil
-      without a =? x, error:
-        check error.msg == "proc or iterator is nil"
-        return
-      fail
-
-    test()
-
-  test "without statement with error handles iterators as well":
-    when (NimMajor, NimMinor) != (2, 0):
-      proc test =
-        var x: iterator: int = nil
-        without a =? x, error:
-          check error.msg == "proc or iterator is nil"
-          return
-        fail
-
-      test()
-
   test "without statement with error can be used more than once":
     proc test =
       without a =? 42.success, error:
@@ -454,17 +412,6 @@ suite "result":
       for i in 0..<1000:
         spawn fail(i)
 
-  test "without statement doesn't interfere with generic code called elsewhere":
-    proc foo(_: type): ?!int =
-      if error =? success(1).errorOption:
-        discard
-
-    proc bar {.used.} = # defined, but not used
-      without x =? bool.foo(), error:
-        discard error
-
-    discard bool.foo() # same type parameter 'bool' as used in bar()
-
   test "catch can be used to convert exceptions to results":
     check parseInt("42").catch == 42.success
     check parseInt("foo").catch.error of ValueError
@@ -643,19 +590,6 @@ suite "result":
     someProc(42.success)
     someProc(int.failure "some error")
 
-type TypeWithSideEffect = object
-proc `$`*(value: TypeWithSideEffect): string {.sideEffect.} =
-  discard
-
-suite "result side effects":
-
-  test "without statement with error works when `$` has side effects":
-    proc foo =
-      without x =? TypeWithSideEffect.failure("error"), error:
-        discard error
-        return
-      fail()
-    foo()
 
 import pkg/questionable/resultsbase
 
@@ -663,7 +597,7 @@ suite "result compatibility":
 
   type R = Result[int, string]
   let good = R.ok 42
-  let bad = R.err "some error"
+  let bad = R.err "error"
 
   test "|?, =? and .option work on other types of Result":
     check bad |? 43 == 43
@@ -681,13 +615,3 @@ suite "result compatibility":
       fail
     without b =? good:
       fail
-
-  test "without statement with error works on other type of Result":
-    without value =? bad, error:
-      check error of ResultFailure
-      check error.msg == "some error"
-
-  test "without statement with error works on Result[T, void]":
-    without value =? Result[int, void].err, error:
-      check error of ResultFailure
-      check error.msg == "Result is an error"