mruby-mruby/doc/limitations.md

Limitations and Differences

The philosophy of mruby is to be a lightweight implementation of the Ruby ISO standard. These two objectives are partially contradicting. Ruby is an expressive language with complex implementation details which are difficult to implement in a lightweight manner. To cope with this, limitations to the "Ruby Compatibility" are defined.

This document is collecting these limitations.

Integrity

This document does not contain a complete list of limitations. Please help to improve it by submitting your findings.

1/2 gives 0.5

Since mruby does not have Bignum, bigger integers are represented by Float numbers. To enhace interoperability between Float and Float, mruby provides Float#upto``` and other iterationg methods for ```Float class. As a side effect, 1/2 gives 0.5 not 0.

Array passed to puts

Passing an Array to puts results in different output.

puts [1,2,3]

Ruby [ruby 2.0.0p645 (2015-04-13 revision 50299)]

1
2
3

mruby [1.2.0 (2015-11-17)]

[1, 2, 3]

Kernel.raise in rescue clause

Kernel.raise without arguments does not raise the current exception within a rescue clause.

begin
  1 / 0
rescue
  raise
end

Ruby [ruby 2.0.0p645 (2015-04-13 revision 50299)]

ZeroDivisionError is raised.

mruby [1.2.0 (2015-11-17)]

No exception is raised.