"HeldExpression" (Interpreter Type)

Wolfram Language expression.

Details

Allowed Forms

  • Any valid Wolfram Language expression.

Restriction Specifications

Interpretation

Examples

Basic Examples  (5)

Interpret expressions and avoid evaluation:

In[1]:=
Click for copyable input
Out[1]=
In[2]:=
Click for copyable input
Out[2]=

No evaluation is attempted when matching the choices:

In[1]:=
Click for copyable input
Out[1]=
In[2]:=
Click for copyable input
Out[2]=

By default, only expressions with no side effect are allowed:

In[1]:=
Click for copyable input
Out[1]=

This can be changed by allowing All symbols:

In[2]:=
Click for copyable input
Out[2]=

Restrict to a list of symbols:

In[1]:=
Click for copyable input
Out[1]=
In[2]:=
Click for copyable input
Out[2]=

By default, new symbols are created in $Context, but a custom context can be specified:

In[1]:=
Click for copyable input
Out[1]=
Out[1]=
In[2]:=
Click for copyable input
Out[2]=
Out[2]=

Related Interpreters

See Also

Interpreter  Restricted  Failure  HoldComplete