Extend your language: Difference between revisions

=={{header|F_Sharp|F#}}==

<lang fsharp>

// Extend your language. Nigel Galloway: September 14th., 2021

type elsetf=TF

type elseft=FT

type elseff=FF

let elsetf,elseft,elseff=TF,FT,FF

let if2 n g tt (TF:elsetf)tf (FT:elseft)ft (FF:elseff)ff=match(n,g) with (true,true)->tt() |(true,false)->tf() |(false,true)->ft() |_->ff()

if2 (13<23) (23<42) (fun()->printfn "tt")

elsetf (fun()->printfn "tf")

elseft (fun()->printfn "ft")

elseff (fun()->printfn "ff")

if2 (13<23) (42<23) (fun()->printfn "tt")

elsetf (fun()->printfn "tf")

elseft (fun()->printfn "ft")

elseff (fun()->printfn "ff")

if2 (23<23) (23<42) (fun()->printfn "tt")

elsetf (fun()->printfn "tf")

elseft (fun()->printfn "ft")

elseff (fun()->printfn "ff")

if2 (23<13) (42<23) (fun()->printfn "tt")

elsetf (fun()->printfn "tf")

elseft (fun()->printfn "ft")

elseff (fun()->printfn "ff")

</lang>

{{out}}

<pre>

tt

tf

ft

ff

</pre>

Looking at some possible errors found by the compiler:

<lang fsharp>

if2 (13<23) (23<42) (fun()->printfn "tt")

elseff (fun()->printfn "tf")

elseft (fun()->printfn "ft")

elseff (fun()->printfn "ff")

</lang>

{{out}}

<pre>

This expression was expected to have type

'elsetf'

but here has type

'elseff'

</pre>

<lang fsharp>

if2 (13<23) (42<23) (fun()->printfn "tt")

elsetx (fun()->printfn "tf")

elseft (fun()->printfn "ft")

elseff (fun()->printfn "ff")

</lang>

{{out}}

<pre>

The value or constructor 'elsetx' is not defined. Maybe you want one of the following:

elsetf

elseft

elseff

</pre>