Function definition: Difference between revisions
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=={{header|BASIC}}==
==={{header|ANSI BASIC}}===
In ANSI BASIC, functions can be defined as either formulas or multi-line external or internal subroutines. External functions are independent program units that can be called from within the program. Internal functions are considered part of the program unit they are contained in and can only be called from within that unit. External functions do not share any information with other program units and exchange information through parameters and returned values. Internal functions share everything with their surrounding program unit except for their parameters. Internal functions do not have local variables.
{{works with|Decimal BASIC}}
<syntaxhighlight lang="basic">
100 DEF Multiply(A,
120 DECLARE EXTERNAL FUNCTION MultiplyE
130 PRINT Multiply(3, 1.23456)
140 PRINT MultiplyI(3, 1.23456)
150 PRINT MultiplyE(3, 1.23456)
160 FUNCTION MultiplyI(X, Y)
170 LET MultiplyI = X * Y
180 END FUNCTION
190 END
200 EXTERNAL FUNCTION MultiplyE(A, B)
210 LET MultiplyE = A * B
220 END FUNCTION
</syntaxhighlight>
{{out}}
<pre>
3.70368
3.70368
3.70368
</pre>
==={{header|Applesoft BASIC}}===
Line 770 ⟶ 788:
<syntaxhighlight lang="freebasic">#Define multiply(d1, d2) (d1) * (d2)</syntaxhighlight>
==={{header|FutureBasic}}===
<syntaxhighlight lang="futurebasic">window 1
local fn multiply( a as long, b as long ) as long
end fn = a * b
print fn multiply( 3, 9 )
HandleEvents</syntaxhighlight>
Output:
<pre>
27
</pre>
==={{header|Gambas}}===
Line 958 ⟶ 990:
{{out}}
<pre> 3.703680038452148</pre>
==={{header|QuickBASIC}}===
{{works with|QBasic}}
<syntaxhighlight lang="qbasic">DECLARE FUNCTION multiply% (a AS INTEGER, b AS INTEGER)
FUNCTION multiply% (a AS INTEGER, b AS INTEGER)
multiply = a * b
END FUNCTION</syntaxhighlight>
==={{header|REALbasic}}===
Line 1,047 ⟶ 1,087:
return a * b
end sub</syntaxhighlight>
==={{header|Xojo}}===
<syntaxhighlight lang="vbnet">Function Multiply(ByVal a As Integer, ByVal b As Integer) As Integer
Return a * b
End Function</syntaxhighlight>
Call the function
<syntaxhighlight lang="vbnet">Dim I As Integer = Multiply(7, 6)</syntaxhighlight>
==={{header|ZX Spectrum Basic}}===
Line 1,107 ⟶ 1,154:
In lambda calculus, multiplication on Church numerals is <code>mul = \m \n \f. m (n f)</code> which in BLC is
<
If mul is used several times within an expression E, then they can share the same definition by using <code>(\mul. E)(\m\n\f. m (n f))</code>. For example, the cube function is <code>\n. (\mul. mul n (mul n n)) (\m\n\f. m (n f))</code> which in BLC is
<
=={{header|BQN}}==
Line 1,172 ⟶ 1,219:
return a*b;
}</syntaxhighlight>
=={{header|Chapel}}==
<syntaxhighlight lang="text">
proc multiply(a, b)
{
return a * b;
}
</syntaxhighlight>
Can require that the two arguments be of the same type.
<syntaxhighlight lang="text">
proc multiply(a : ?t ... 2)
{
return a(0) * a(1)
}
</syntaxhighlight>
Will work on any type where the * operator is defined.
=={{header|ChucK}}==
Line 1,827 ⟶ 1,893:
let multiply (x: i32, y: i32) : i32 = x * y
</syntaxhighlight>
=={{header|GAP}}==
Line 2,150 ⟶ 2,202:
=={{header|langur}}==
Langur functions are first-order. They are pure in terms of setting values and in terms of I/O (unless declared impure).
A return statement may be used, but a function's last value is its implicit return value.
=== parameters ===
Parameters are defined within parentheses after the fn token. To specify no parameters, use an empty set of parentheses.
<syntaxhighlight lang="langur">val .multiply = fn(.x, .y) { .x * .y }
.multiply(3, 4)</syntaxhighlight>
=== operator implied functions ===
Operator implied functions are built using an infix operator between curly braces on an
<syntaxhighlight lang="langur">val .multiply = fn{*}
.multiply(3, 4)</syntaxhighlight>
=== nil left partially implied functions ===
These are built with an infix operator and
<syntaxhighlight lang="langur">val .times3 = fn{* 3}
map .times3, [1, 2, 3]</syntaxhighlight>
=== impure functions (I/O) ===
Impure functions must be declared as such.
<syntaxhighlight>val .writeit = impure fn(.x) { writeln .x }</syntaxhighlight>
Impure functions cannot be passed to pure functions.
=={{header|Lasso}}==
Line 3,609 ⟶ 3,656:
<syntaxhighlight lang="scheme">(define multiply
(lambda (x y) (* x y)))</syntaxhighlight>
=={{header|XPL0}}==
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