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Added 'lenient ops' module (#6754)

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* added 'lenient ops' module

* made lenient ops inline/noSideEffect; updated copyright

* moved tests into external module

* added warning for the '==' operator

* mentioned lenientops in the standard library overview

* removed test on nimout -- too fragile

* removed `==` and moved doc link to core section
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Fabian Keller 2017-11-21 13:22:27 +01:00 • committed by Andreas Rumpf
commit 6abdd7cbf6
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#
#
# Nim's Runtime Library
# (c) Copyright 2017 Nim contributors
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module offers implementations of common binary operations
## like ``+``, ``-``, ``*``, ``/`` and comparison operations,
## which work for mixed float/int operands.
## All operations convert the integer operand into the
## type of the float operand. For numerical expressions, the return
## type is always the type of the float involved in the expresssion,
## i.e., there is no auto conversion from float32 to float64.
##
## Note: In general, auto-converting from int to float loses
## information, which is why these operators live in a separate
## module. Use with care.
##
## Regarding binary comparison, this module only provides unequal operators.
## The equality operator ``==`` is omitted, because depending on the use case
## either casting to float or rounding to int might be preferred, and users
## should make an explicit choice.
import typetraits
proc `+`*[I: SomeInteger, F: SomeReal](i: I, f: F): F {.noSideEffect, inline.} =
F(i) + f
proc `+`*[I: SomeInteger, F: SomeReal](f: F, i: I): F {.noSideEffect, inline.} =
f + F(i)
proc `-`*[I: SomeInteger, F: SomeReal](i: I, f: F): F {.noSideEffect, inline.} =
F(i) - f
proc `-`*[I: SomeInteger, F: SomeReal](f: F, i: I): F {.noSideEffect, inline.} =
f - F(i)
proc `*`*[I: SomeInteger, F: SomeReal](i: I, f: F): F {.noSideEffect, inline.} =
F(i) * f
proc `*`*[I: SomeInteger, F: SomeReal](f: F, i: I): F {.noSideEffect, inline.} =
f * F(i)
proc `/`*[I: SomeInteger, F: SomeReal](i: I, f: F): F {.noSideEffect, inline.} =
F(i) / f
proc `/`*[I: SomeInteger, F: SomeReal](f: F, i: I): F {.noSideEffect, inline.} =
f / F(i)
proc `<`*[I: SomeInteger, F: SomeReal](i: I, f: F): bool {.noSideEffect, inline.} =
F(i) < f
proc `<`*[I: SomeInteger, F: SomeReal](f: F, i: I): bool {.noSideEffect, inline.} =
f < F(i)
proc `<=`*[I: SomeInteger, F: SomeReal](i: I, f: F): bool {.noSideEffect, inline.} =
F(i) <= f
proc `<=`*[I: SomeInteger, F: SomeReal](f: F, i: I): bool {.noSideEffect, inline.} =
f <= F(i)
# Note that we must not defined `>=` and `>`, because system.nim already has a
# template with signature (x, y: untyped): untyped, which would lead to
# ambigous calls.