• IAL introduced the three-level concept of reference, publication and hardware language, and the concept of "word delimiters" having a separate representation from freely chosen identifiers (hence, no reserved words). ALGOL 60 kept this three-level concept. • The distinction between assignment (:= representing a left-facing arrow) and the equality relation = was introduced in IAL and kept in ALGOL 60. • Both IAL and ALGOL 60 allow arrays with arbitrary lower and upper subscript bounds, and allow subscript bounds to be defined by integer expressions. • Both IAL and ALGOL 60 allow nesting of procedure declarations and the corresponding identifier scopes. • The IAL report described parameter substitution in much the same terms as the ALGOL 60 report, leaving open the possibility of
call by name. It is unclear if this was realized at the time. • IAL allows numeric statement labels, that ALGOL 60 kept. • The possibility of including non-ALGOL code within a program was already hinted at, in the context of parameters to procedures. • Both IAL and ALGOL 60 have a
switch designator, unrelated, however, to the
switch statement in C and other languages. • In-line functions of the form
f(
x) :=
x / 2; were proposed in IAL but
dropped in ALGOL 60. • IAL procedure declarations provide separate declaration lists for input and output parameters, a procedure can return multiple values; this mechanism was
replaced in ALGOL 60 with the
value declaration. • Variable declarations in IAL can be placed
anywhere in the program and not necessarily at the beginning of a procedure. In contrast, the declarations within an ALGOL 60 block should occur
before all execution statements. • The -statement has the form for i:=base(increment)limit, directly resembling the loop of Rutishauser's programming language
Superplan, replacing =with :=, and replacing its German keyword Für with the direct English translation for; ALGOL 60 replaced the parentheses with the word delimiters step and until, such that the previous statement instead would be
i:=
base increment limit. • The IAL -statement does not have a -clause or -clause; it rather
guards the succeeding statement. IAL provides an -statement that cleanly allows testing of multiple conditions. Both were replaced by ALGOL's - construct, with the introduction of the "
dangling-" ambiguity. • IAL provides macro-substitution with the -statement; this was dropped in ALGOL 60. • IAL allows one or more array subscripts to be omitted when passing arrays to procedures, and to provide any or all arguments to a procedure passed to another procedure. • IAL's infix Boolean operators are all of the same precedence level. Exponents are indicated with paired up and down arrows, which removed any confusion about the correct interpretation of nested exponents; ALGOL 60 replaced the paired arrows with a single up-arrow whose function is equivalent to FORTRAN's
**. • The IAL report does not explicitly specify which standard functions were to be provided, making a vague reference to the "standard functions of analysis." The ALGOL 60 report has a more explicit list of standard functions. ==References==