CM-Yacc should be installed through Smackage, an ML package manager (see http://github.com/standardml/smackage).
$ smackage
$ smackage get cmyacc
$ smackage make cmyacc (this will just display the various options)
To install CM-Yacc (for Standard ML)
$ smackage make cmyacc mlton (or smlnj or win+smlnj)
$ smackage make cmyacc install
$ cmyacc
Error: not enough input files
Usage: cmyacc file.cmyacc [-o file.sml]
(Default output file is file.cmyacc.sml)
To install CM-Yacc-HS (for Haskell)
$ smackage make cmyacc mlton+hs (or smlnj+hs or win+smlnj+hs)
$ smackage make cmyacc install+hs
$ cmyacc
Error: not enough input files
Usage: cmyacc-hs file.cmyacc [-o file.hs]
(Default output file is file.cmyacc.hs)
It is possible to install CM-Yacc without Smackage: just make sure that CM-Lib
v1 (see http://github.com/standardml/cmlib) is installed somewhere on your
system, and change the reference to $SMACKAGE/cmlib/v1 in
sources-generic.cm and/or the reference to $(SMACKAGE)/cmlib/v1 in
sources-generic.mlb to point to the directory where CMlib lives.